Java内部类



内部类共有四种

1.static inner class静态内部类.<该类属于类本身的StaticInner.Innerinner = new StaticInner.Inner();>

   a.只能够访所在类的静态的成员变量或方法

                   packagecom.cb.innerclass;

public class StaticInnerClass {

public static void main(String[] args) {

StaticInner.Inner inner = new StaticInner.Inner();

inner.test();

}

}

class StaticInner {

private static int a = 4;

private int b=5;

public static class Inner {

public void test() {

System.out.println(a);

// System.out.println(b);不能访问

}

}

}

2.Member inner class 成员内部类  （没有用static来修饰）<该类属于类的对象MemberInner.Innerinner = (new MemberInner()).new Inner();>

   a.可以访问一切所在类的成员和方法

      package com.cb.innerclass;

class MemberInner {

private int a = 4;

public class Inner {

private int a=5;

public void doSomething() {

System.out.println(MemberInner.this.a);

}

}

}

public class MemberInnerClass {

public static void main(String[] args) {

MemberInner.Inner inner = (new MemberInner()).new Inner();// 实例化

inner.doSomething();

}

}

3.LocalInner Class 局部内部类

   定义在方法中，只能访问所在内中被final修饰的类型变量

   class LocalInner {

publicfinal int b=3;

public voiddosomething() {

final inta=4;

class Inner{

public voidtest() {

System.out.println("HelloWorld!!!");

System.out.println(a+b);

}

}

newInner().test();

}

}

publicclass LocalInnerClassTest {

publicstatic void main(String[] args) {

LocalInnerlocalInner = new LocalInner();

localInner.dosomething();

}

}

4.匿名内部类（AnonymousInner Class）会隐式的继承一个父类或者接口

packagecom.cb.innerclass;

importjava.util.Date;

publicclass AnonymousInnerClassTest {

publicString gert(Date date) {

returndate.toLocaleString();

}

publicstatic void main(String args[]) {

AnonymousInnerClassTesttest = new AnonymousInnerClassTest();

// Stringstr=test.gert(new Date());

//System.out.println(str);

String str= test.gert(new Date() {// 生成了一个继承了Date类的一个子类的对象

publicString toLocaleString() {

return  "Hello World!!!";

}

});

System.out.println(str);

}

}