Preparing%20Java%20Programs

1
Chapter 5

• Preparing Java Programs

2
Program development
3
Program development
pico prog.java
javac prog.java
java prog
4
High-level languages

• Machine language computers native language.
• Add two numbers 00100111 1010 0101
• Assembly language uses mnemonics.
• Add two numbers ADD R1 R2
• An assembly code needs to be translated to
  machine code.

5
High-level languages

• High-level programming languages bridging the
  gap between machine language and natural
  languages.
• Examples COBOL, Fortran, Algol, C
• Add two numbers (in C) Z A B
• Compilation translation to machine code.

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A Java program

• A sample Java program
• // A Java program to read a number and compute
  and display its square.
• import java.io.
• class square
• public static void main(String arg) throws
  IOException
• int n
• BufferedReader stdin new BufferedReader
• (new InputStreamReader (System.in))
• System.out.print ("Enter the number to be
  square ")
• n Integer.parseInt (stdin.readLine())
• System.out.println ("The square of " n "
  is " nn)

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Compilation in Java

• Use the javac command to compile
• javac prog.java
• Produces the object file with extension .class
  (eg prog.class)
• To run object file, use the java command
• java prog

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Errors

• Compilation errors occur during compilation.
• Reason syntax errors.
• Easy to rectify.
• Run-time errors occur during execution.
• Reasons logic errors, data errors, computation
  errors.
• Harder to rectify.

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Homework

• Try exercises in chapter 5.