Core Java Tutorial

Java History • Java is a general purpose , object-oriented programming language. • The fastest growing programming language in the history of computing • Developed by Sun Microsystems of USA in 1991. • Originally it is called Oak by James Gosling. • Originally designed in 1991 for use in embedded consumer applications • Java team …

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• Simple • Architecture-neutral • Object-oriented • Portable • Distributed • High-performance • Interpreted • Multithreaded • Robust • Dynamic • Secure Simple: Java is a simple language as it does not use pointers, preprocessor header files; go to statement and many more others. Object oriented: In Java everything is object. All program code and …

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Benefits of Java over C and C++ • Architecturally neutral. Once written, the same Java program can be run on any platform computer and operating system) that supports Java. • Entirely object-oriented. Existing code can be easily re-used and maintained. • Secure. Dangerous program actions are prohibited. • Supports Internet programming. Java applets are run …

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How Java works • To develop and distribute a Java program 1. Programmer codes Java source statements 2. Java compiler converts source statements into bytecode (platform-independent object     language) 3. Bytecode is copied to the target platform • To execute a Java program 1. Platform-dependent Java Virtual Machine (JVM) software must be installed 2. A copy …

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The Java Programming Language Java is a high-level programming language that is all of the following: • Simple • Architecture-neutral • Object-oriented • Portable • Distributed • High-performance • Interpreted • Multithreaded • Robust • Dynamic • Secure Java is also unusual in that each Java program is both compiled and interpreted. With a compiler, …

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A platform is the hardware or software environment in which a program runs. The Java platform differs from most other platforms in that it’s a software-only platform that runs on top of other, hardware-based platforms. Most other platforms are described as a combination of hardware and operating system. The Java platform has two components: • …

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The Java Development Kit comes with a collection of tools that are used for developing and running Java programs. They include: • appletviewer ( for viewing Java applet) • javac (Java compiler) • java (Java Interpreter) • javap (Java disassembler) • javah (for C header files) • javadoc (for creating HTML documents) • jdb (Java …

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HARDWARE AND SOFTWARE REQUIREMENTS Java is currently supported on Window 95, Window NT, Sun Solaries, Macintosh and UNIX machine. The minimum software and hardware requirement for 95 version of Java are as follows: • IBM-compatible 486 system • Minimum of 8 MB memory • Windows 95 software • A Windows-compatible sound card • A hard …

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Disadvantages of Java � Not supported by all platforms (though third-party JVM software is usually available) � Slower in execution than compiled languages � Restricts or prohibits machine-level operations required by certain applications (operating systems, etc.)  

Developing the Java Application A Java application is a standalone Java program– a program written in the Java language that runs independently of any browser. Example: /** * The HelloWorldApp class implements an application that * simply displays “Hello World!” to the standard output. */ class HelloWorldApp { public static void main(String[] args) { System.out.println(“Hello …

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Comments in Java Code The bold characters in the following listing are comments. /** * The HelloWorldApp class implements an application that * simply displays “Hello World!” to the standard output. */ class HelloWorldApp { public static void main(String[] args) { System.out.println(“Hello World!”); //Display the string. } } The Java language supports three kinds of …

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Defining a Class The first bold line in the following listing begins a class definition block. /** * The HelloWorldApp class implements an application that * simply displays “Hello World!” to the standard output. */ class HelloWorldApp { public static void main(String[] args) { System.out.println(“Hello World!”); //Display the string. } } A class–the basic building …

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The main Method The first bold line in the following listing begins the definition of a main method. /** * The HelloWorldApp class implements an application that * simply displays “Hello World!” to the standard output. */ class HelloWorldApp { public static void main(String[] args) { System.out.println(“Hello World!”); //Display the string. } } Every Java …

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Using Classes and Objects The “Hello World” application is about the simplest Java program one can write that actually does something. Because it is such a simple program, it doesn’t need to define any classes except for HelloWorldApp. The “Hello World” application does use another class–the System class–that is part of the API (application programming …

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Java Program Structure A Java program may contain one or more section which is as follow: 1. Documentation section (suggested) The documentation section comprises a set of comment line of the program, the author and other details, which the programmer would like to refer to at a later stage. 2. Package statement (Optional) This statement …

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Java Tokens The smallest individual units in a program are known as TOKEN. A java program is a collection of tokens, comments and white spaces. Java language includes five types of tokens They are: 1) Reserved Keyword 2) Identifiders 3) Literals 4) Operator 5) Separators Reserved Keyword Keywords have specific meaning and implement specific features …

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Variables are locations in memory in which values can be stored. Each one has a name, a type, and a value. Before we can use a variable, we have to declare it. After it is declared, we can then assign values to it. Java actually has three kinds of variables: 1. instance variables, 2. class …

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