20_内部类

Posted 2021-02-19 bajiaotai

 

 1.概念

 

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 2.内部类的作用

 

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 3.原理

 

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 4.分类

 

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 5.内部类中为什么不能声明静态成员？

 

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 6.成员内部类的修饰符

 

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 7.局部内部类的修饰符

 

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 8.成员内部类

 

8.1 成员内部类代码实现

package JavaBasicReview;

public class JavaGrammer {
    public static void main(String[] args) {
        //创建外部类,外部类在内部类之前创建，内部类创建后会获取外部类对象的引用
        Outer outer = new Outer();
        outer.getInner();
        System.out.println("====it‘s Inner======");
        //创建成员内部类,使用内部类之前，外部类会自动创建
        Outer.Inner inner = new Outer().new Inner();
        inner.show();
    }
}


class Outer {
    private int age = 16;

    public Outer() {
        System.out.println("Outer created!");
    }

    //成员内部类
    class Inner {
        private int age = 17;

        public Inner() {
            System.out.println("Inner created！");
        }

        void show() {
            System.out.println("Outer‘s age:" + Outer.this.age);
            System.out.println("Inner‘s age:" + this.age);
        }
    }

    void getInner() {
        Inner inner = new Inner();
        System.out.println("Outer‘s age:" + this.age);
        System.out.println("Inner‘s age:" + inner.age);
    }
    
}

Outer created!
Inner created！
Outer‘s age:16
Inner‘s age:17
====it‘s Inner======
Outer created!
Inner created！
Outer‘s age:16
Inner‘s age:17