Code blocks in Java basics

What is a block of code

In Java, code that is enclosed in {} is called a block of code.

Code block classification

1. Local code block: Code that is in the local variable position and enclosed in {} to limit the life cycle of the local variable.
2. Building blocks of code: The position of the member variable in the class and the code enclosed in {}, and the construction method at the same level, are called once each time the constructor method is called, so it is called constructing the code block.
3. Static code block: The position of the member variable in the class and the code enclosed in {}, but you need to add a static keyword before {}

What's the difference?

1. Local code blocks are used in local locations to define the life cycle.
2. The purpose of constructing a code block is to put together the same code in multiple construction methods, call once before instantiating the object, and multiple objects appear multiple times.
3. Static code blocks occur when classes are initialized, and multiple objects share one.
4. code block cannot be explicitly called

Sample code

/*** Created by Lili on 15/10/17.*/classcodearea{//Static code block    Static {        inty = 100;    System.out.println (y); }    //Building Code Blocks    {        intx = 10;    SYSTEM.OUT.PRINTLN (x); }     PublicCodearea () {System.out.println ("------construct function 1-------"); }    //constructing a code block does not have to appear before the construction method and can be anywhere at the same level, but is called before the method is constructed.    {        intx = 20;    SYSTEM.OUT.PRINTLN (x); }     PublicCodearea (intm) {System.out.println ("------Construct function 2-------"); }    {        intx = 30;    SYSTEM.OUT.PRINTLN (x); }    //The static construction method, regardless of how many times it occurs, is called before the code block and construction method are constructed.    Static {        inty = 200;    System.out.println (y); }    {        intx = 40;    SYSTEM.OUT.PRINTLN (x); }} Public classCodeareatest { Public Static voidMain (String args[]) {{intx = 1;        SYSTEM.OUT.PRINTLN (x); } System.out.println ("--------Split 1----------"); Codearea codeArea0=NewCodearea (); Codearea codeArea1=NewCodearea (1); }}

Run results

1--------split 1----------10020010203040------construct function 1-------10203040------construct function 2-------  0

Code blocks in Java basic Java