First knowledge of Java

Javase is mainly used for desktop applications, console development.

1-1 Some of the most common Java words:

public.

Class

Static statically.

void no return type

Main

String strings

Args parameter

of system Systems

Out output device

Print printing

Write the first code:

1  Public class Hello java{2          Public Static void Main (string[] args) {3                 System.out.print ("Hello java");// code 4        }  5 }

Input specification: 1. Each level of the program and the previous level of the program staggered, with the TAB key, empty out of 8 spaces;

2. The curly braces are aligned with this level of code.

Common errors: 1. The class name "Hello Java" must be consistent with the program file name (and the casing needs to be consistent);

2.main method as the entrance of the program, Void is necessary;

3. "String", "System" S must be in the same capitalization, or there will be a program error, Java is case-sensitive;

4. The code line semicolon must have;

5. Quotation marks cannot be omitted.

1-2 notes for Java programs:

 1  public  class       hello java{ 2  public  static  void   main (string[] args) { 3  System.out.print (" Hello Java "); //  single-line comment  4  /*  5   multiline comment  6   multiline comment  7  */ 8  }  9 } 

1. The single-line comment begins with "//" and ends at the end of the line;

2. Multi-line annotations such as the above procedure.

1-3 several common output controls for Java

\ t: outputs 8 spaces, which is equivalent to a tab stop.

\ n: Line break.

11 Public classtest{22 Public Static voidMain (string[] args) {33 System.out.print ("Hello java\n");44 System.out.print ("you \ t good java");55     }66 }77//Output Results88Hello Java99 Hello Java

Note: The output control must be unloaded inside the double quotation mark.

First knowledge of Java