"Code block" local code block + Construction code block + static code block

1. Local code block

Location: In the method of the class

Presentation method: {}

Function: Control the life cycle of variables, reduce memory consumption

Demo

 Public class Localcode {    publicstaticvoid  main (String [] args) {        int y = ten;        {            int x = +;            SYSTEM.OUT.PRINTLN (x);        }        System.out.println (y);//Run to at this point the X variable has been garbage collected    }}

2. Building code Blocks

Location: in class

Presentation method: {}

Function: Used to initialize each object to reduce the amount of code

Demo

 Public classConstructcode {PrivateString name; {System.out.println ("Construct Code---"); Eat ();//constructor in which the method is extracted and placed in this construction code block} constructcode () {System.out.println ("Drink----");//System.out.println ("Eat---");} constructcode (String name) {//System.out.println ("eat----");SYSTEM.OUT.PRINTLN (name + "Drink----"); }    Private voideat () {System.out.println ("Eat---"); }     Public Static voidMain (String[]args) {Constructcode C=NewConstructcode (); Constructcode Constructcode=NewConstructcode ("XL"); }}

Console output:

"D:\Program Files\java\jdk1.7.0_13\bin\java"-agentlib:jdwp=transport=dt_socket,address=127.0.0.1:59499,suspend= Y,server=n-dfile.encoding=utf-8-classpath "D:\Program Files\java\jdk1.7.0_13\jre\lib\charsets.jar;d:\program Files\java\jdk1.7.0_13\jre\lib\deploy.jar;d:\program Files\java\jdk1.7.0_13\jre\lib\javaws.jar;d:\program Files\ Java\jdk1.7.0_13\jre\lib\jce.jar;d:\program Files\java\jdk1.7.0_13\jre\lib\jfr.jar;d:\program Files\Java\ Jdk1.7.0_13\jre\lib\jfxrt.jar;d:\program Files\java\jdk1.7.0_13\jre\lib\jsse.jar;d:\program Files\Java\jdk1.7.0_ 13\jre\lib\management-agent.jar;d:\program Files\java\jdk1.7.0_13\jre\lib\plugin.jar;d:\program Files\Java\ Jdk1.7.0_13\jre\lib\resources.jar;d:\program Files\java\jdk1.7.0_13\jre\lib\rt.jar;d:\program Files\Java\ Jdk1.7.0_13\jre\lib\ext\access-bridge-64.jar;d:\program Files\java\jdk1.7.0_13\jre\lib\ext\dnsns.jar;d:\program Files\java\jdk1.7.0_13\jre\lib\ext\jaccess.jar;d:\program files\java\jdk1.7.0_13\jre\lib\ext\localedata.jar;d:\ Program Files\java\jdk1.7.0_13\jre\lib\ext\sunec.jar;d:\program files\java\jdk1.7.0_13\jre\lib\ext\sunjce_provider.jar;d:\ Program Files\java\jdk1.7.0_13\jre\lib\ext\sunmscapi.jar;d:\program Files\java\jdk1.7.0_13\jre\lib\ext\zipfs.jar ;D: \cxlwork\stsworkspace\work-test\target\classes;d:\app\repository\org\springframework\spring-core\4.1.6. Release\spring-core-4.1.6.release.jar;d:\app\repository\commons-logging\commons-logging\1.2\ Commons-logging-1.2.jar;d:\app\repository\org\springframework\spring-context\4.1.6.release\ Spring-context-4.1.6.release.jar;d:\app\repository\org\springframework\spring-context-support\4.1.6.release\ Spring-context-support-4.1.6.release.jar;d:\app\repository\org\springframework\spring-beans\4.1.6.release\ Spring-beans-4.1.6.release.jar;d:\app\repository\org\springframework\spring-expression\4.1.6.release\ Spring-expression-4.1.6.release.jar;d:\app\repository\org\springframework\spring-aspects\4.1.6.release\ Spring-aspects-4.1.6.release.jar;d:\app\repository\org\aspectj\aspectjweAver\1.8.5\aspectjweaver-1.8.5.jar;d:\app\repository\org\springframework\spring-aop\4.1.6.release\ Spring-aop-4.1.6.release.jar;d:\app\repository\aopalliance\aopalliance\1.0\aopalliance-1.0.jar;d:\app\ Repository\org\springframework\spring-jdbc\4.1.6.release\spring-jdbc-4.1.6.release.jar;d:\app\repository\org\ Springframework\spring-orm\4.1.6.release\spring-orm-4.1.6.release.jar;d:\app\repository\org\springframework\ spring-tx\4.1.6.release\spring-tx-4.1.6.release.jar;d:\app\repository\org\springframework\spring-web\4.1.6. Release\spring-web-4.1.6.release.jar;d:\app\repository\org\springframework\spring-webmvc\4.1.6.release\ Spring-webmvc-4.1.6.release.jar;d:\app\repository\mysql\mysql-connector-java\5.1.9\ Mysql-connector-java-5.1.9.jar;d:\app\repository\org\apache\logging\log4j\log4j-api\2.4.1\log4j-api-2.4.1.jar ;D: \app\repository\org\apache\logging\log4j\log4j-core\2.4.1\log4j-core-2.4.1.jar;d:\program Files (x86) \ Jetbrains\intellij idea 14.0.3\lib\idea_rt.jar "com.raipeng.work.codeblock.ConstructCodeConnected to the target VM, address:' 127.0.0.1:59499 ', Transport: ' Socket 'disconnected from the target VM, address:' 127.0.0.1:59499 ', Transport: ' Socket 'Construct Code---Eat---Drink----Construct Code---Eat---XL Drink----Process finished with exit code0

3. Static code block

Location: in class

Representation method: static{}

Function: Initializes a class, executes as the class is loaded, and executes only once

Demo

 Public classStaticcode {PrivateString name; Static{System.out.println ("Static"); }     PublicStaticcode () {System.out.println ("Construct"); }     PublicStaticcode (String name) {System.out.println (name+ "Name construct"); }     Public Static voidmain (String [] args) {Staticcode s=NewStaticcode (); Staticcode Staticcode=NewStaticcode ("XL"); }}

The console output is as follows:

Static CONSTRUCTXL   name construct0

"Code block" local code block + Construction code block + static code block