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Dubai

Java Basics PPT

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Published in: Java And J2EE | Java Script
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Java is a widely used programming language expressly designed for use in the distributed environment of the internet. It is the most popular programming language for Android smartphone applications and is also among the most favored for the development of edge devices and the internet of things.

Saideepthi K / Dubai

12 years of teaching experience

Qualification: M.Tech

Teaches: Computer Science, Java And J2EE, Python Programming, Java, Python

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  1. JAVA —Object Oriented Programming Language
  2. ' Java is a high-level programming language originally developed by Sun Microsystems and released in 1995. ' Java is guaranteed to be Write Once, Run Anywhere. ' Object Oriented ' Platform Independent Simple Secure ' Architecture-neutral Portable ' Robust ' Multithreaded ' Interpreted
  3. ' High Performance ' Distributed ' Dynamic
  4. ' Popular Java Editors ' To write your Java programs, you will need a text editor. There are even more sophisticated IDES available in the market. But for now, you can consider one of the following - ' Notepad - On Windows machine, you can use any simple text editor like Notepad (Recommended for this tutorial), TextPad. ' Netbeans - A Java IDE that is open-source and free which can be downloaded from https://www.netbeans.org/index.html. ' Eclipse - A Java IDE developed by the eclipse open-source community and can be downloaded from https://www.eclipse.org/.
  5. ' When we consider a Java program, it can be defined as a collection of objects that communicate via invoking each other's methods. ' Object - Objects have states and behaviors. Example: A dog has states - color, name, breed as well as behavior such as wagging their tail, barking, eating. An object is an instance of a class. ' Class - A class can be defined as a template/blueprint that describes the behavior/state that the object of its type supports. ' Methods - A method is basically a behavior. A class can contain many methods. It is in methods where the logics are written, data is manipulated and all the actions are executed. ' Instance Variables - Each object has its unique set of instance variables. An object's state is created by the values assigned to these instance variables.
  6. ' My first Program public class MyFirstJavaProgram { / * This is my first java program. * This will print Il-lello Worldl as the output public static void main(String []args) { System.out.println("Hello World"); // prints Hello World
  7. Let's look at how to save the file, compile, and run the program. Please follow the subsequent steps - Open notepad and add the code as above. Save the file as: MyFirstJavaProgram.java. Open a command prompt window and go to the directory where you saved the class. Assume it's C:. Type Ijavac MyFirstJavaProgram.javaI and press enter to compile your code. If there are no errors in your code, the command prompt will take you to the next line (Assumption : The path variable is set). Now, type java MyFirstJavaProgram to run your program. You will be able to see Hello World printed on the window.
  8. Basic Syntax ' Case Sensitivity - Java is case sensitive, which means identifier Hello and hello would have different meaning in Java. ' Class Names - For all class names the first letter should be in Upper Case. If several words are used to form a name of the class, each inner word's first letter should be in Upper Case. ' Example: class MyFirstJavaClass ' Method Names - All method names should start with a Lower Case letter. If several words are used to form the name of the method, then each inner word's first letter should be in Upper Case. ' Example: public void myMethodName()
  9. ' Program File Name - Name of the program file should exactly match the class name. ' When saving the file, you should save it using the class name (Remember Java is case sensitive) and append I.javal to the end of the name (if the file name and the class name do not match, your program will not compile). ' But please make a note that in case you do not have a public class present in the file then file name can be different than class name. It is also not mandatory to have a public class in the file. ' Example: Assume 'MyFirstJavaProgramI is the class name. Then the file should be saved as 'MyFirstJavaProgram.java' public static void main(String args[]) - Java program processing starts from the main() method which is a mandatory part of every Java program.
  10. ' Java Identifiers ' All Java components require names. Names used for classes, variables, and methods are called identifiers. ' In Java, there are several points to remember about identifiers. They are as follows - ' All identifiers should begin with a letter (A to Z or a to z), currency character ($) or an underscore (_). ' After the first character, identifiers can have any combination of characters. ' A key word cannot be used as an identifier. ' Most importantly, identifiers are case sensitive. ' Examples of legal identifiers: age, $salary, _ value, ' Examples of illegal identifiers: 123abc, -salary. 1 value.
  11. ' Java Modifiers ' Like other languages, it is possible to modify classes, methods, etc., by using modifiers. There are two categories of modifiers - ' Access Modifiers - default, public , protected, private ' Non-access Modifiers - final, abstract, strictfp ' Java Variables ' Following are the types of variables in Java - ' Local Variables ' Class Variables (Static Variables) ' Instance Variables (Non-static Variables)
  12. ' Java Arrays ' Arrays are objects that store multiple variables of the same type. However, an array itself is an object on the heap. We will look into how to declare, construct, and initialize in the upcoming chapters. ' Java Enums ' Enums were introduced in Java 5.0. Enums restrict a variable to have one of only a few predefined values. The values in this enumerated list are called ' With the use of enums it is possible to reduce the number of bugs in your code. ' For example, if we consider an application for a fresh juice shop, it would be possible to restrict the glass size to small, medium, and large. This would make sure that it would not allow anyone to order any size other than small, medium, or large.
  13. class FreshJuice { enum FreshJuiceSize{ SMALL, MEDIUM, LARGE } FreshJuiceSize size; public class FreshJuiceTest { public static void main(String args[]) { FreshJuice juice = new FreshJuice(); juice.size = FreshJuice.FreshJuiceSize.MEDlUM System.out.println("Size: " + juice.size);
  14. ' Java Keywords abstract byte class do extends for import long private short switch throws volatile assert case const double final goto instanceof native protected static synchronized transient while boolean catch continue else finally int new public strictfp this try break char default enum float implements interface package return super throw void
  15. 1. EXECUTION OF A JAVA PROGRAM Static loading: A block of code would be loaded into the RAM before it executed ( i.e after being loaded into the RAM it may or may not get executed ) Dynamic loading: A block of code would be loaded into the RAM only when it is required to be executed. Note: Static loading took place in the execution of structured programming languages. EX: c- language Java follows the Dynamic loading JVM would not convert all the statements of the class file into its executable code at a time. Once the control comes out from the method, then it is deleted from the RAM and another method of exe type will be loaded as required. Once the control comes out from the main ( ), the main ( ) method would also be deleted from the RAM. This is why we are not able to view the exe contents of a class file.
  16. Functions of JVM(Java Virtual Machine): It converts the required part if the bytecode into its equivalent executable code. It loads the executable code into the RAM. Executes this code through the local operating system. Deletes the executable code from the RAM.
  17. We know that JVM converts the class file into its equivalent executable code. Now if a JVM is in windows environment executable code that is understood by windows environment only. Similarly, same in the case with UNIX or other or thus JVM ID platform dependent. Java, With the help of this course, students can now get a confidant to write a basic program to in-depth algorithms in C Programming or Java Programming to understand the basics one must visit the list 500 Java programs to get an idea. But the platform dependency of the JVM is not considered while saying Java is platform independent because JVM is supplied free of cost through the internet by the sun microsystems.
  18. Comments in Java: Java supports single-line and multi-line comments very similar to C and C++. All characters available inside any comment are ignored by Java compiler. public class MyFirstJavaProgram { / * This is my first java program. * This will print 'Hello World' as the output * This is an example of multi-line comments. public static void main(String []args) { // This is an example of single line comment / * This is also an example of single line comment. System.out.println("Hello World");
  19. Using Blank Lines A line containing only white space, possibly with a comment, is known as a blank line, and Java totally ignores it. Inheritance In Java, classes can be derived from classes. Basically, if you need to create a new class and here is already a class that has some of the code you require, then it is possible to derive your new class from the already existing code. This concept allows you to reuse the fields and methods of the existing class without having to rewrite the code in a new class. In this scenario, the existing class is called the superclass and the derived class is called the subclass.
  20. Interfaces In Java language, an interface can be defined as a contract between objects on how to communicate with each other. Interfaces play a vital role when it comes to the concept of inheritance. An interface defines the methods, a deriving class (subclass) should use. But the implementation of the methods is totally up to the subclass.
  21. Java is an Object-Oriented Language. As a language that has the Object-Oriented feature, Java supports the following fundamental concepts - Polymorphism Inheritance Encapsulation Abstraction Classes Objects Instance Method Message Passing
  22. Object - Objects have states and behaviors. Example: A dog has states - color, name, breed as well as behaviors — wagging the tail, barking, eating. An object is an instance of a class. Class - A class can be defined as a template/blueprint that describes the behavior/state that the object of its type support. Classes in Java A class is a blueprint from which individual objects are created. Following is a sample of a class.
  23. public class Dog { String breed; int age; String color; void barking() { void hungry() { void sleeping() {
  24. A class can contain any of the following variable types. Local variables - Variables defined inside methods, constructors or blocks are called local variables. The variable will be declared and initialized within the method and the variable will be destroyed when the method has completed. Instance variables - Instance variables are variables within a class but outside any method. These variables are initialized when the class is instantiated. Instance variables can be accessed from inside any method, constructor or blocks of that particular class. Class variables - Class variables are variables declared within a class, outside any method, with the static keyword.
  25. A class can have any number of methods to access the value of various kinds of methods. In the above example, barking(), hungry() and sleeping() are methods. Following are some of the important topics that need to be discussed when looking into classes of the Java Language. Constructors When discussing about classes, one of the most important sub topic would be constructors. Every class has a constructor. If we do not explicitly write a constructor for a class, the Java compiler builds a default constructor for that class. Each time a new object is created, at least one constructor will be invoked. The main rule of constructors is that they should have the same name as the class. A class can have more than one constructor.
  26. public class Animal{ public Animal() { public Animal(String name) { // This constructor has one parameter, name.
  27. Creating an Object A class provides the blueprints for objects. So basically, an object is created from a class. In Java, the new keyword is used to create new objects. There are three steps when creating an object from a class - Declaration - A variable declaration with a variable name with an object type. Instantiation - The 'new/ keyword is used to create the object. Initialization - The 'newl keyword is followed by a call to a constructor. This call initializes the new object.
  28. public class Animal { public Animal(String name) { // This constructor has one parameter, name. System.out.println("Passed Name is :" + name ); public static void main(String []args) { // Following statement would create an object myAnimal Animal myAnimal= new Animal( "tommy" );
  29. Accessing Instance Variables and Methods Instance variables and methods are accessed via created objects. To access an instance variable, following is the fully qualified path - / * First create an object * / ObjectReference = new Constructor(); / * Now call a variable as follows * / / * Now you can call a class method as follows * / O bj re n M eth o d N a m ( ) ;
  30. Example public class Animal { int animalAge; public Animal(String name) { // This constructor has one parameter, name. System.out.println("Name chosen is + name ); public void setAge( int age ) { animalAge = age; public int getAge( ) { System.out.println("Puppy's age is . return animalAge; + animalAge ); public static void main(String []args) { / * Object creation * / Animal myAnimal= new Animal( "tommy" ); * Call class method to set puppy's a e
  31. Source File Declaration Rules: These rules are essential when declaring classes, import statements and package statements in a source file. There can be only one public class per source file. A source file can have multiple non-public classes. The public class name should be the name of the source file as well which should be appended by Java at the end. For example: the class name is public class Employee{} then the source file should be as Employee.java. If the class is defined inside a package, then the package statement should be the first statement in the source file.
  32. If import statements are present, then they must be written between the package statement and the class declaration. If there are no package statements, then the import statement should be the first line in the source file. Import and package statements will imply to all the classes present in the source file. It is not possible to declare different import and/or package statements to different classes in the source file.
  33. Classes have several access levels and there are different types Of classes; abstract classes, final classes, etc. Java also has some special classes called Inner classes and Anonymous classes. Java Package In simple words, it is a way of categorizing the classes and interfaces. When developing applications in Java, hundreds of classes and interfaces will be written, therefore categorizing these classes is a must as well as makes life much easier.
  34. Import Statements In Java if a fully qualified name, which includes the package and the class name is given, then the compiler can easily locate the source code or classes. Import statement is a way of giving the proper location for the compiler to find that particular class. For example, the following line would ask the compiler to load all the classes available in directory java _ installation/java/io - import java.io.*
  35. import java.io. * public class Employee { String name; int age; String designation; double salary; // This is the constructor of the class Employee public Employee(String name) { this.name = name; // Assign the age of the Employee to the variable age. public void empAge(int empAge) { age = empAge; / * Assign the designation to the variable designation.*/ public void empDesignation(String empDesig) { designation = empDesig;
  36. / * Assign the salary to the variable salary.*/ public void empSalary(double empSalary) { salary = empSalary; / * Print the Employee details * / public void printEmpIoyee() { System.out.println("Name:"+ name ); System.out.println("Age:" + age ); System.out.println("Designation:" + designation ); System.out.println("Salary:" + salary);
  37. public class EmployeeTest { public static void main(String args[]) { / * Create two objects using constructor * / Employee empOne = new Employee("James Smith"); Employee empTwo = new Employee("Mary Anne"); // Invoking methods for each object created empOne.empAge(26); empOne.empDesignation("Senior Software Engineer"); empOne.empSalary(1000); empOne.printEmployee(); empTwo.empAge(21); empTwo.empDesignation("Software Engineer"); empTwo.empSalary(500); empTwo.printEmployee();
  38. Java — Constructors ' A constructor initializes an object when it is created. It has the same name as its class and is syntactically similar to a method. However, constructors have no explicit return type. ' Typically, you will use a constructor to give initial values to the instance variables defined by the class, or to perform any other start-up procedures required to create a fully formed object. ' All classes have constructors, whether you define one or not, because Java automatically provides a default constructor that initializes all member variables to zero. However, once you define your own constructor, the default constructor is no longer used.
  39. class ClassName { ClassName() { Java allows two types of constructors namely - No argument Constructors Parameterized Constructors No argument Constructors As the name specifies the no argument constructors of Java does not accept any parameters instead, using these constructors the instance variables of a method will be initialized with fixed values for all objects.
  40. Public class MyCIass { Int num; MyClass() { num = 100; public class ConsDemo { public static void main(String args[]) { MyClass tl = new MyClass(); MyClass t2 = new MyClass(); System.out.println(tl.num + + t2.num);
  41. Parameterized Constructors Most often, you will need a constructor that accepts one or more parameters. Parameters are added to a constructor in the same way that they are added to a method, just declare them inside the parentheses after the constructor's name. // A simple constructor. class MyClass { int x; // Following is the constructor MyCIass(int i ) {
  42. public class ConsDemo { public static void main(String args[]) { MyClass tl = new MyClass( 10 ); MyClass t2 = new MyClass( 20 ); System.out.println(tl.x + + t2.x);
  43. Java - Basic Datatypes Variables are nothing but reserved memory locations to store values. This means that when you create a variable you reserve some space in the memory. Based on the data type of a variable, the operating system allocates memory and decides what can be stored in the reserved memory. Therefore, by assigning different data types to variables, you can store integers, decimals, or characters in these variables. There are two data types available in Java - Primitive Data Types Reference/Object Data Types
  44. Primitive Data Types There are eight primitive datatypes supported by Java. Primitive datatypes are predefined by the language and named by a keyword. Let us now look into the eight primitive data types in detail. byte Byte data type is an 8-bit signed two's complement integer Minimum value is -128 (-2A7) Maximum value is 127 -1) Default value is 0 Byte data type is used to save space in large arrays, mainly in place of integers, since a byte is four times smaller than an integer. Example: byte a = 100, byte b = -50
  45. short Short data type is a 16-bit signed two's complement integer Minimum value is -32,768 (-2A15) Maximum value is 32,767 (inclusive) (2A15 -1) Short data type can also be used to save memory as byte data type. A short is 2 times smaller than an integer Default value is O. Example: short s = 10000, short r = -20000
  46. int Int data type is a 32-bit signed two's complement integer. Minimum value is - (-2A31) Maximum value is 2,147,483,647(inclusive) (2A31 -1) Integer is generally used as the default data type for integral values unless there is a concern about memory. The default value is O Example: int a = 100000, int b = -200000
  47. long Long data type is a 64-bit signed two's complement integer Minimum value is Maximum value is -1) This type is used when a wider range than int is needed Default value is OL Example: long a = 100000L, long b = -200000L
  48. float Float data type is a single-precision 32-bit IEEE 754 floating point Float is mainly used to save memory in large arrays of floating point numbers Default value is 0.0f Float data type is never used for precise values such as currency Example: float fl = 234.5f
  49. double double data type is a double-precision 64-bit IEEE 754 floating point This data type is generally used as the default data type for decimal values, generally the default choice Double data type should never be used for precise values such as currency Default value is 0.0d Example: double dl - — 123.4
  50. boolean boolean data type represents one bit of information There are only two possible values: true and false This data type is used for simple flags that track true/false conditions Default value is false Example: boolean one = true
  51. char char data type is a single 16-bit Unicode character Minimum value is IUOOOOI (or O) Maximum value is Iuffffl (or 65,535 inclusive) Char data type is used to store any character Example: char letterA = IAI
  52. Reference Datatypes Reference variables are created using defined constructors of the classes. They are used to access objects. These variables are declared to be of a specific type that cannot be changed. For example, Employee, Puppy, etc. Class objects and various type of array variables come under reference datatype. Default value of any reference variable is null. A reference variable can be used to refer any object of the declared type or any compatible type. Example: Animal animal = new Animal("giraffe");
  53. Java Literals A literal is a source code representation of a fixed value. They are represented directly in the code without any computation. Literals can be assigned to any primitive type variable. For example - byte a = 68; char a = byte, int, long, and short can be expressed in decimal(base 10), hexadecimal(base 16) or octal(base 8) number systems as well. Prefix 0 is used to indicate octal, and prefix Ox indicates hexadecimal when using these number systems for literals. For example - int decimal = 100; int octal = 0144; int hexa =
  54. String literals in Java are specified like they are in most other languages by enclosing a sequence of characters between a pair of double quotes. Examples of string literals are - Example 'Hello World" "twonlines" "" This is in quotes String and char types of literals can contain any Unicode characters. For example char a = Iu00011; - "u0001"; String a -
  55. Java language supports few special escape sequences for String and char literals as well. They are - Notation n b s t ddd uxxxx Character represented Newline (Ox0a) Carriage return (OxOd) Formfeed (Ox0c) Backspace Space tab Double quote Single quote backslash Octal character (ddd) Hexadecimal UNICODE character (xxxx)
  56. Java — Variable Types Local variables Instance variables Class/Static variables
  57. Local Variables Local variables are declared in methods, constructors, or blocks. Local variables are created when the method, constructor or block is entered and the variable will be destroyed once it exits the method, constructor, or block. Access modifiers cannot be used for local variables. Local variables are visible only within the declared method, constructor, or block. Local variables are implemented at stack level internally. There is no default value for local variables, so local variables should be declared and an initial value should be assigned before the first use.
  58. Example Here, age is a local variable. This is defined inside pupAge() method and its scope is limited to only this method. public class Test { public void pupAge() { int age = 110; age = age + 7; System.out.printIn("Puppy age is : " + age); public static void main(String args[]) { Test test = new Test(); test.pupAge();
  59. Example Following example uses age without initializing it, so it would give an error at the time of compilation. public class Test { public void pupAge() { int age; age = age + 7; System.out.printIn("Puppy age is : " + age); public static void main(String args[]) { Test test = new Test(); test.pupAge();
  60. Instance Variables Instance variables are declared in a class, but outside a method, constructor or any block. When a space is allocated for an object in the heap, a slot for each instance variable value is created. Instance variables are created when an object is created with the use of the keyword 'newl and destroyed when the object is destroyed. Instance variables hold values that must be referenced by more than one method, constructor or block, or essential parts of an object's state that must be present throughout the class. Instance variables can be declared in class level before or after use. Access modifiers can be given for instance variables. The instance variables are visible for all methods, constructors and block in the class. Normally, it is recommended to make these variables private (access level). However, visibility for subclasses can be given for these variables with the use of access modifiers.
  61. Instance variables have default values. For numbers, the default value is O, for Booleans it is false, and for object references it is null. Values can be assigned during the declaration or within the constructor. Instance variables can be accessed directly by calling the variable name inside the class. However, within static methods (when instance variables are given accessibility), they should be called using the fully qualified name. ObjectReference.VariabIeName.
  62. Example import java.io.* public class Employee { // this instance variable is visible for any child class. public String name; // salary variable is visible in Employee class only. private double salary; // The name variable is assigned in the constructor. public Employee (String empName) { name = empName; // The salary variable is assigned a value. public void setSalary(double empSal) { salary = empSal;
  63. // This method prints the employee details. public void printEmp() { System.out.println("name + name ) ; System.out.println("salary :" + salary); public static void main(String args[]) { Employee empOne = new Employee("Ransika"); empOne.setSalary(1000); empOne.printEmp();
  64. Class/Static Variables Class variables also known as static variables are declared with the static keyword in a class, but outside a method, constructor or a block. There would only be one copy of each class variable per class, regardless of how many objects are created from it. Static variables are rarely used other than being declared as constants. Constants are variables that are declared as public/private, final, and static. Constant variables never change from their initial value.
  65. Static variables are stored in the static memory. It is rare to use static variables other than declared final and used as either public or private constants. Static variables are created when the program starts and destroyed when the program stops. Visibility is similar to instance variables. However, most static variables are declared public since they must be available for users of the class. Default values are same as instance variables. For numbers, the default value is O; for Booleans, it is false; and for object references, it is null. Values can be assigned during the declaration or within the constructor. Additionally, values can be assigned in special static initializer blocks.
  66. Static variables can be accessed by calling with the class name ClassName.VariableName. When declaring class variables as public static final, then variable names (constants) are all in upper case. If the static variables are not public and final, the naming syntax is the same as instance and local variables.
  67. Example import java.io.* public class Employee { // salary variable is a private static variable private static double salary; // DEPARTMENT is a constant public static final String DEPARTMENT = "Development ' public static void main(String args[]) { salary = 1000; System.out.println(DEPARTMENT + "average salary:" + salary); This will produce the following result - Output Development average salary:1000
  68. Java - Modifier Types Modifiers are keywords that you add to those definitions to change their meanings. Java language has a wide variety of modifiers, including the following Java Access Modifiers Non Access Modifiers To use a modifier, you include its keyword in the definition of a class, method, or variable. The modifier precedes the rest of the statement, as in the following example.
  69. Example public class className { private boolean myFlag; static final double weeks = 9.5; protected static final int BOXWIDTH = 42; public static void main(String[] arguments) { // body of method
  70. Access Control Modifiers Java provides a number of access modifiers to set access levels for classes, variables, methods and constructors. The four access levels are - Visible to the package, the default. No modifiers are needed. Visible to the class only (private). Visible to the world (public). Visible to the package and all subclasses (protected).
  71. Non-Access Modifiers Java provides a number of non-access modifiers to achieve many other functionality. The static modifier for creating class methods and variables. The final modifier for finalizing the implementations of classes, methods, and variables. The abstract modifier for creating abstract classes and methods. The synchronized and volatile modifiers, which are used for threads.
  72. Java - Basic Operators Java provides a rich set of operators to manipulate variables. We can divide all the Java operators into the following groups - Arithmetic Operators Relational Operators Bitwise Operators Logical Operators Assignment Operators Misc Operators
  73. The Arithmetic Operators Arithmetic operators are used in mathematical expressions in the same way that they are used in algebra. The following table lists the arithmetic operators - Assume integer variable A holds 10 and variable B holds 20, then - Show Examples
  74. Operator + (Addition) - (Subtraction) * (Multiplication) / (Division) % (Modulus) ++ (Increment) -- (Decrement) Description Adds values on either side of the operator. Subtracts right-hand operand from left-hand operand. Multiplies values on either side of the operator. Divides left-hand operand by right-hand operand. Divides left-hand operand by right-hand operand and returns remainder. Increases the value of operand by 1. Decreases the value of operand by 1. Example A + B will give 30 A- B will give -10 A* B will give 200 B/ A will give 2 B % A will give 0 B++ gives 21 B-- gives 19
  75. ' The Relational Operators ' There are following relational operators supported by Java language. ' Assume variable A holds 10 and variable B holds 20, then - ' Show Examples
  76. Operator == (equal to) != (not equal to) > (greater than) < (less than) >= (greater than or equal to) B) is not true. (A < B) is true. (A >= B) is not true. (A B) is true.
  77. The Bitwise Operators Java defines several bitwise operators, which can be applied to the integer types, long, int, short, char, and byte. Bitwise operator works on bits and performs bit-by-bit operation. Assume if a = 60 and b = 13; now in binary format they will be as follows - a = 0011 1100 b = 0000 1101 = 0000 1100 alb = 0011 1101 aAb = 0011 0001 = 1100 0011 The following table lists the bitwise operators - Assume integer variable A holds 60 and variable B holds 13 then
  78. Operator & (bitwise and) I (bitwise or) (bitwise XOR) (bitwise compliment) (left shift) >> (right shift) >>> (zero fill right shift) Description Binary AND Operator copies a bit to the result if it exists in both operands. Binary OR Operator copies a bit if it exists in either operand. Binary XOR Operator copies the bit if it is set in one operand but not both. Binary Ones Complement Operator is unary and has the effect of 'flipping' bits. Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand. Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand. Shift right zero fill operator. The left operands value is moved right by the number of bits specified by the right operand and shifted values are filled up with zeros. Example (A & B) will give 12 which is 0000 1100 (A I B) will give 61 which is 0011 1101 (A B) will give 49 which is 0011 0001 (NA ) will give -61 which is 1100 0011 in 21s complement form due to a signed binary number. 0000 A >>>2 will give 15 which is 0000
  79. ' The Logical Operators ' The following table lists the logical operators - ' Assume Boolean variables A holds true and variable B holds false, then - ' Show Examples
  80. Operat or Description Called Logical AND operator. If both the operands are non- (logical zero, then the and) condition becomes true. Called Logical OR Operator. If any of the two operands (logical are non-zero, then or) the condition becomes true. Called Logical NOT Operator. Use to reverses the logical state of its operand. (logical If a condition is true not) then Logical NOT operator will make false. Example B) is false is true B) is true
  81. ' The Assignment Operators ' Following are the assignment operators supported by Java language - ' Show Examples
  82. Operator Description Simple assignment operator. Assigns values from right side operands to left side operand. Add AND assignment operator. It adds right operand to the left operand and assign the result to left operand. Subtract AND assignment operator. It subtracts right operand from the left operand and assign the result to left operand. Multiply AND assignment operator. It multiplies right operand with the left operand and assign the result to left operand. Divide AND assignment operator. It divides left operand with the right operand and assign the result to left operand. Modulus AND assignment operator. It takes modulus using two operands and assign the result to left operand. Left shift AND assignment operator. Right shift AND assignment operator. Bitwise AND assignment operator. bitwise exclusive OR and assignment operator. bitwise inclusive OR and assignment operator. Example C = A + B will assign value of A + B into C C += A is equivalent to C = C C -= A is equivalent to C = C— C A is equivalent to C = C C /= A is equivalent to C = C/ A is equivalent to C = C 2 is same as C- 2 is same as C- C 2 is same as C=C&2 c 2 is same as C = CA 2 C is same asC=C12
  83. ' Miscellaneous Operators ' There are few other operators supported by Java Language. ' Conditional Operator ( ? : ) ' Conditional operator is also known as the ternary operator. This operator consists of three operands and is used to evaluate Boolean expressions. The goal of the operator is to decide, which value should be assigned to the variable. The operator is written as - ' variable x = (expression) ? value if true : value if false ' Following is an example -
  84. public class Test { public static void main(String args[]) { int a, b; System.out.println( "Value of b is : b (a 10) ? 30; System.out.println( "Value of b is :
  85. instanceof Operator This operator is used only for object reference variables. The operator checks whether the object is of a particular type (class type or interface type). instanceof operator is written as - ( Object reference variable ) instanceof (class/interface type) If the object referred by the variable on the left side of the operator passes the IS-A check for the class/interface type on the right side, then the result will be true. Following is an example -
  86. public class Test { public static void main(String args[]) { String name = "James' // following will return true since name is type of String boolean result = name instanceof String; System.out.println( result );
  87. This operator will still return true, if the object being compared is the assignment compatible with the type on the right. Following is one more example - Example class Vehicle {} public class Car extends Vehicle { public static void main(String args[]) { Vehicle a = new Car(); boolean result = a instanceof Car; System.out.println( result ); This will produce the following result - Output true
  88. Precedence of Java Operators Operator precedence determines the grouping of terms in an expression. This affects how an expression is evaluated. Certain operators have higher precedence than others; for example, the multiplication operator has higher precedence than the addition operator - For example, x = 7 + 3 * 2; here x is assigned 13, not 20 because operator * has higher precedence than +, so it first gets multiplied with 3 * 2 and then adds into 7. Here, operators with the highest precedence appear at the top of the table, those with the lowest appear at the bottom. Within an expression, higher precedence operators will be evaluated first.
  89. Java - Loop Control There may be a situation when you need to execute a block of code several number of times. In general, statements are executed sequentially: The first statement in a function is executed first, followed by the second, and so on. Programming languages provide various control structures that allow for more complicated execution paths. A loop statement allows us to execute a statement or group of statements multiple times and following is the general form of a loop statement in most of the programming languages -
  90. Conditional Code If condition is true Condition If condition is false
  91. ' Java programming language provides the following types of loop to handle looping requirements. Sr.No. 1 2 3 Loop & Description while loopRepeats a statement or group of statements while a given condition is true. It tests the condition before executing the loop body. for loopExecute a sequence of statements multiple times and abbreviates the code that manages the loop variable. do...while loopLike a while statement, except that it tests the condition at the end of the loop body.
  92. ' A while loop statement in Java programming language repeatedly executes a target statement as long as a given condition is true. Syntax ' The syntax of a while loop is - while(Boolean_expression) { // Statements ' Here, statement(s) may be a single statement or a block of statements. The condition may be any expression, and true is any non zero value.
  93. ' When executing, if the boolean _ expression result is true, then the actions inside the loop will be executed. This will continue as long as the expression result is true. ' When the condition becomes false, program control passes to the line immediately following the loop.
  94. while( condition ) conditional code ; condition If condition is true code block If condition is false
  95. Example public class Test { public static void main(String args[]) { int x = 10; while( x < 20 ) { System.out.print("value of x : System.out.print("n");
  96. for loop in java A for loop is a repetition control structure that allows you to efficiently write a loop that needs to be executed a specific number of times. A for loop is useful when you know how many times a task is to be repeated. Syntax The syntax of a for loop is - for(initialization; Boolean _ expression; update) { // Statements
  97. Here is the flow of control in a for loop - The initialization step is executed first, and only once. This step allows you to declare and initialize any loop control variables and this step ends with a semi colon Next, the Boolean expression is evaluated. If it is true, the body of the loop is executed. If it is false, the body of the loop will not be executed and control jumps to the next statement past the for loop.
  98. After the body of the for loop gets executed, the control jumps back up to the update statement. This statement allows you to update any loop control variables. This statement can be left blank with a semicolon at the end. The Boolean expression is now evaluated again. If it is true, the loop executes and the process repeats (body of loop, then update step, then Boolean expression). After the Boolean expression is false, the for loop terminates.
  99. for( init; condition; increment ) conditional code Init condition If condition is true code block increment O If condition is false
  100. ' Example Following is an example code of the for loop in Java. public class Test { public static void main(String args[]) { for(intx= 10; x < 20; x=x+ 1) { System.out.print("value of x : " + x ); System.out.print("n");
  101. do while loop in java ' A do...while loop is similar to a while loop, except that a do...while loop is guaranteed to execute at least one time. Syntax ' Following is the syntax of a do...while loop - do { // Statements }while(Boolean_expression);
  102. ' Notice that the Boolean expression appears at the end of the loop, so the statements in the loop execute once before the Boolean is tested. ' If the Boolean expression is true, the control jumps back up to do statement, and the statements in the loop execute again. This process repeats until the Boolean expression is false.
  103. do { conditional code ; } while (condition) code block If condition is true condition If condition is false O
  104. ' Example public class Test { public static void main(String args[]) { int x = 10; do { System.out.print("value of x : System.out.print("n"); }while( x < 20 );
  105. Loop Control Statements Loop control statements change execution from its normal sequence. When execution leaves a scope, all automatic objects that were created in that scope are destroyed. Java supports the following control statements. Click the following links to check their detail.
  106. Sr.No. 1 2 Control Statement & Description break statementTerminates the loop or switch statement and transfers execution to the statement immediately following the loop or switch. continue statementCauses the loop to skip the remainder of its body and immediately retest its condition prior to reiterating.
  107. Break statement in java The break statement in Java programming language has the following two usages - When the break statement is encountered inside a loop, the loop is immediately terminated and the program control resumes at the next statement following the loop. It can be used to terminate a case in the switch statement (covered in the next chapter). Syntax The syntax of a break is a single statement inside any loop - break;
  108. conditional code If condition is true condition If condition is false break
  109. Example public class Test { public static void main(String args[]) { int [ ] numbers = {10, 20, 30, 40, 50}; for(int x : numbers ) { if( x = break; System.out.print( x ); System.out.print("n");
  110. Continue statement in java The continue keyword can be used in any of the loop control structures. It causes the loop to immediately jump to the next iteration of the loop. In a for loop, the continue keyword causes control to immediately jump to the update statement. In a while loop or do/while loop, control immediately jumps to the Boolean expression.
  111. conditional code If condition continue is true condition If condition is false
  112. Example public class Test { public static void main(String args[]) { int [ ] numbers = {10, 20, 30, 40, 50}; for(int x : numbers ) { if( x = continue; System.out.print( x ); System.out.print("n");
  113. Enhanced for loop in Java As of Java 5, the enhanced for loop was introduced. This is mainly used to traverse collection of elements including arrays. Syntax Following is the syntax of enhanced for loop - for(declaration : expression) { // Statements
  114. Declaration - The newly declared block variable, is of a type compatible with the elements of the array you are accessing. The variable will be available within the for block and its value would be the same as the current array element. Expression - This evaluates to the array you need to loop through. The expression can be an array variable or method call that returns an array.
  115. Example public class Test { public static void main(String args[]) { int [ ] numbers = {10, 20, 30, 40, 50}; for(int x : numbers ) { System.out.print( x ); System.out.pnnt( , System.out.print("n"); String [ ] names = {"James" " La rry" , for( String name : names ) { System.out.print( name ); System.out.pnnt( , "Toml I Lacy"};
  116. if statement in java An if statement consists of a Boolean expression followed by one or more statements. Syntax Following is the syntax of an if statement - if(Boolean_expression) { // Statements will execute if the Boolean expression is true If the Boolean expression evaluates to true then the block of code inside the if statement will be executed. If not, the first set of code after the end of the if statement (after the closing curly brace) will be executed.
  117. If condition is true condition If condition conditional code
  118. ' Example public class Test { public static void main(String args[]) { int x = 10; if( x < 20 ) { System.out.print("This is if statement");
  119. ' if-else statement in java ' An if statement can be followed by an optional else statement, which executes when the Boolean expression is false. Syntax ' Following is the syntax of an if...else statement - if(Boolean_expression) { // Executes when the Boolean expression is true }else { // Executes when the Boolean expression is false ' If the boolean expression evaluates to true, then the if block of code will be executed, otherwise else block of code will be executed.
  120. If condition is true condition If condition if code is false else code
  121. ' Example public class Test { public static void main(String args[]) { int x = 30; if( x < 20 ) { System.out.print("This is if statement"); }else { System.out.print("This is else statement");
  122. The if... else if... else ' An if statement can be followed by an optional else if...else statement, which is very useful to test various conditions using single if...else if statement. ' When using if, else if, else statements there are a few points to keep in mind. ' An if can have zero or one else's and it must come after any else if's. ' An if can have zero to many else if's and they must come before the else. ' Once an else if succeeds, none of the remaining else if's or else's will be
  123. Syntax ' Following is the syntax of an if...else statement - if(Boolean_expression 1) { // Executes when the Boolean expression 1 is true }else if(BooIean_expression 2) { // Executes when the Boolean expression 2 is true }else if(Boolean_expression 3) { // Executes when the Boolean expression 3 is true }else { // Executes when the none of the above condition is true.
  124. ' Example public class Test { public static void main(String args[]) { int x = 30; if( x = = 10) { System.out.print("VaIue of X is 10"); }else if( x 20) { System.out.print("VaIue of X is 20"); }else if( x = = 30) { System.out.print("VaIue of X is 30"); }else { System.out.print("This is else statement");
  125. ' nested if statement in java ' It is always legal to nest if-else statements which means you can use one if or else if statement inside another if or else if statement. Syntax ' The syntax for a nested if...else is as follows - if(Boolean_expression 1) { // Executes when the Boolean expression 1 is true if(BooIean_expression 2) { // Executes when the Boolean expression 2 is true ' You can nest else if...else in the similar way as we have nested if statement.
  126. Example public class Test { public static void main(String args[]) { int x = 30; int y = 10; if( x = System.out.print(")( = 30 and Y = 10 )
  127. switch statement in java A switch statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each case. Syntax The syntax of enhanced for loop is - switch(expression) { case value : // Statements break; // optional case value : // Statements break; // optional // You can have any number of case statements. default : // Optional // Statements
  128. The following rules apply to a switch statement - The variable used in a switch statement can only be integers, convertable integers (byte, short, char), strings and enums. You can have any number of case statements within a switch. Each case is followed by the value to be compared to and a colon. The value for a case must be the same data type as the variable in the switch and it must be a constant or a literal. When the variable being switched on is equal to a case, the statements following that case will execute until a break statement is reached.
  129. When a break statement is reached, the switch terminates, and the flow of control jumps to the next line following the switch statement. Not every case needs to contain a break. If no break appears, the flow of control will fall through to subsequent cases until a break is reached. A switch statement can have an optional default case, which must appear at the end of the switch. The default case can be used for performing a task when none of the cases is true. No break is needed in the default case.
  130. expression case 1 code block 1 case 2 code block 2 case 3 code block 3 default code block N
  131. Example public class Test { public static void main(String args[]) { // char grade = args[0].charAt(0); char grade = 'C'; switch(grade) { case 'A' : System.out.println("Excellent!"); break; case 'B' case 'C' : System.out.println("Well done"); break; case 'D' : System.out.println("You passed"); case 'F' : System.out.println("Better try again"); break; default : System.out.println("lnvalid grade"); System.out.println("Your grade is " + grade);
  132. ' The ? : Operator ' We have covered conditional operator ? : in the previous chapter which can be used to replace if...else statements. It has the following general form - Expl ? Exp2 : Exp3; ' Where Expl, Exp2, and Exp3 are expressions. Notice the use and placement of the colon. ' To determine the value of the whole expression, initially expl is evaluated. ' If the value of expl is true, then the value of Exp2 will be the value of the whole expression. ' If the value of expl is false, then Exp3 is evaluated and its value becomes the value of the entire expression.
  133. ' Java - Numbers Class ' Normally, when we work with Numbers, we use primitive data types such as byte, int, long, double, etc. Example int i = 5000; float gpa = 13.65; double mask = Oxaf; ' However, in development, we come across situations where we need to use objects instead of primitive data types. In order to achieve this, Java provides wrapper classes. ' All the wrapper classes (Integer, Long, Byte, Double, Float, Short) are subclasses of the abstract class Number.
  134. Byte Integer Number Double Short Float Long
  135. ' The object of the wrapper class contains or wraps its respective primitive data type. Converting primitive data types into object is called boxing, and this is taken care by the compiler. Therefore, while using a wrapper class you just need to pass the value of the primitive data type to the constructor of the Wrapper class. ' And the Wrapper object will be converted back to a primitive data type, and this process is called unboxing. The Number class is part of the java.lang package. ' Following is an example of boxing and unboxing -
  136. ' Example public class Test { public static void main(String args[]) { Integer x = 5; // boxes int to an Integer object x = x + 10; // unboxes the Integer to a int System.out.println(x); When x is assigned an integer value, the compiler boxes the integer because x is integer object. Later, x is unboxed so that they can be added as an integer.
  137. ' Number Methods ' Following is the list of the instance methods that all the subclasses of the Number class implements -
  138. Sr. No. 1 2 3 4 5 6 7 8 9 Method & Description xxxVaIue()Converts the value of this Number object to the xxx data type and returns it. compareTo()Compares this Number object to the argument. equals()Determines whether this number object is equal to the argument. valueOf()Returns an Integer object holding the value of the specified primitive. toString() object String Returns a representing the value of a specified int or Integer. parseInt()This method is used to get the primitive data type of a certain String. abs() Returns the absolute value of the argument. ceil() Returns the smallest integer that is greater than or equal to the argument. Returned as a double. floor() Returns the largest integer that is less than or equal to the argument.
  139. 15 16 17 18 19 20 21 22 23 24 25 26 27 !ggOReturns the natural logarithm of the argument. pgwOReturns the value of the first argument raised to the power of the second argument. sqctOReturns the square root of the argument. sin()Returns the sine of the specified double value. cos()Returns the cosine of the specified double value. tan()Returns the tangent of the specified double value. asin()Returns the arcsine of the specified double value. acos()Returns the arccosine of the specified double value. atan()Returns the arctangent of the specified double value. atan2()Converts rectangular coordinates (x, y) to polar coordinate (r, theta) and returns theta. toDegrees()Converts the argument to degrees. toRadians()Converts the argument to radians. random()Returns a random number.
  140. ' Java - Character Class Example char ch = 'al; // Unicode for uppercase Greek omega character char uniChar = 'u039A'; // an array of chars char[] charArray ={ 'al, 1b', c',
  141. ' However in development, we come across situations where we need to use objects instead of primitive data types. In order to achieve this, Java provides wrapper class Character for primitive data type char. ' The Character class offers a number of useful class (i.e., static) methods for manipulating characters. You can create a Character object with the Character constructor - ' Character ch = new Character('al);
  142. ' The Java compiler will also create a Character object for you under some circumstances. For example, if you pass a primitive char into a method that expects an object, the compiler automatically converts the char to a Character for you. This feature is called autoboxing or unboxing, if the conversion goes the other way. ' Example // Here following primitive char 'al // is boxed into the Character object ch Character ch = 'al; // Here primitive 'x/ is boxed for method test, // return is unboxed to char 'cl char c = test(lxl);
  143. ' Escape Sequences ' A character preceded by a backslash () is an escape sequence and has a special meaning to the compiler. ' The newline character (n) has been used frequently in this tutorial in System.out.println() statements to advance to the next line after the string is printed. ' Following table shows the Java escape sequences -
  144. Escape Sequence b n Description Inserts a tab in the text at this point. Inserts a backspace in the text at this point. Inserts a newline in the text at this point. Inserts a carriage return in the text at this point. Inserts a form feed in the text at this point. Inserts a single quote character in the text at this point. Inserts a double quote character in the text at this point. Inserts a backslash character in the text at this point.
  145. When an escape sequence is encountered in a print statement, the compiler interprets it accordingly. ' Example ' If you want to put quotes within quotes, you must use the escape sequence, ", on the interior quotes - public class Test { public static void main(String args[]) { System.out.println("She said "Hello!" to me.");
  146. ' Character Methods ' Following is the list of the important instance methods that all the subclasses of the Character class implement - ' For a complete list of methods, please refer to the java.lang.Character API specification.
  147. Sr.No. 1 2 3 4 5 6 7 8 Method & Description isLetter()Determines whether the specified char value is a letter. isDigit()Determines whether the specified char value is a digit. isWhitespace()Determines whether the specified char value is white space. isUpperCase()Determines whether the specified char value is uppercase. isLowerCase()Determines whether the specified char value is lowercase. toUpperCase()Returns the uppercase form of the specified char value. toLowerCase()Returns the lowercase form of the specified char value. toString() Returns a String object representing the specified character value that is, a one-character string.
  148. N/A

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