A few getting started applets for Java

1. First the most classic Hello world!

 Public class Hello {    publicstaticvoid  main (String args[]) {         System.out.println ( "Hello world!" );     }}

Hello world!

The difference between 2.print and println

 Public class Hello {    publicstaticvoid  main (String args[]) {        System.out.print ( "Hello world!" );         System.out.println ("Hello world!" );        System.out.println ("Hello world!" );     }}

Hello World!hello world! Helloworld!

Apparently println ended up with a newline and print no, so it's better to use println.

Usage of 3.PRINTLN

 Public class Hello {    publicstaticvoid  main (String args[]) {        int x= 2;        SYSTEM.OUT.PRINTLN (x+ "*" +x+ "=" + (x*x));}     }

2*2=4

The number to be output here is connected with the "+" number.

4. Declaration of Constants

 Public class Hello {        staticfinalint year=365;          Public Static void Main (String args[]) {        System.out.println ("Two years equals" +2*year+ "Day");}     }

Two years equals 730 days.

 Public class Hello {        publicstaticvoid  main (String args[]) {        final int year=365;        System.out.println ("Two years equals" +2*year+ "Day");}     }

Two years equals 730 days.

Constant assignment Syntax final+ data type + variable name = variable value, when constant is used for a member variable of a class, you must assign a value to the constant.

5. Declaration of variables

 Public class Hello {        publicstaticvoid  main (String args[]) {        int Num=3;         Char ch= ' a ';        SYSTEM.OUT.PRINTLN (num+ "is an integer");        SYSTEM.OUT.PRINTLN (Ch+ "is character");}     }

3 is the integer A is the character

These programs are extracted from the Java book, the code in the book itself with the compiler run again, for beginners like me very good.

A few getting started applets for Java