1. BlueJ Venkatesh Ramamoorthy (Venky) Day 3

2. Objectives To use BlueJ –To compile and execute simple JAVA programs –Output-only programs (Hello World and Pledge) –Input-output programs (Adding two numbers) To understand programming errors –Types of errors

3. Our main focus The various menus and buttons used in BlueJ Differences between the types of programming errors

4. The Hello World Program This program displays Hello, World!! on the screen Students type up this program on their computers, then compile and execute the program Then, students modify the program to display multiple lines: Hello, World!! Java is a fun programming language!! We enjoy this semester!!

5. The Pledge Program

6. The Add Program Refer Page 23 of the textbook (by Walter Savitch, 4 th Edition) The program –Takes in two integers –Adds them –Outputs the sum on the screen Students type up this program from the projector screen and compile and execute the program

7. Errors Three types of errors –Compilation –Run-time –Logical

8. Errors – details Compilation errors –Can be caught and corrected before program execution –These are grammatical errors, often called “syntax” errors Run-time errors –System error during program execution –Cannot be caught during compilation Logical errors –Incorrect output or abnormal program execution –Cannot be caught until the program executed at least once –These are often caused due to human errors / oversights