Handout 3 Advanced Programing in Java

Umair Javed CS-391

Java Program Development and Execution Steps
Java program normally go through five phases. These are 1. 2. 3. 4. 5. Edit, Compile, Load, Verify and Execute

We look over all the above mentioned phases in a bit detail. First consider the following figure that summarizes the all phases of a java program.

Phase 1

Editor

Disk

Program is created in the editor and stored on disk. Compiler creates bytecodes and stores them on disk.

Phase 2

Compiler

Disk Primary Memory

Phase 3

Class Loader Class loader puts bytecodes in memory.

Disk

Primary Memory

Phase 4

Bytecode Verifier

Bytecode verifier confirms that all bytecodes are valid and do not violate Java’s security restrictions.

Phase 5

Primary Memory Interpreter

Interpreter reads bytecodes and translates them into a language that the computer can understand, possibly storing data values as the program executes.

Umair© 2005, All Rights Reserved

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TA: Munawar Nadeem

Handout 3 Advanced Programing in Java

Umair Javed CS-391

Phase 1: Edit
Phase 1 consists of editing a file. This is accomplished with an editor program. The programmer types a java program using the editor like notepad, and make corrections if necessary. When the programmer specifies that the file in the editor should be saved, the program is stored on a secondary storage device such as a disk. Java program file name ends with a .java extension. On Windows platform, notepad is a simp le and commonly used editor for the beginners. However java integrated development environments (IDEs) such as NetBeans, Borland JBuilder, JCreator and IBM’s Ecllipse hava built- in editors that are smoothly integrated into the programming environment.

Phase 2: Compile
In Phase 2, the programmer gives the command javac to compile the program. The