15_继承

 

 

 1.定义

class Zi extends Fu {
    //'age' has private access in 'JavaBasicReview.Fu'
    private int age /*= super.age*/;
    private String name = super.name;
    private int num = this.age;

    public void show() {
        System.out.println(name);//fu
        System.out.println(num);//0
    }
}

 

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2.好处

 

 

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 3.格式

 

 

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 4.继承后特点

 

 

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 5.super关键字

 

 

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 6.构造方法

 

 

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 7.继承的特点

 

 

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 8.super和this的内存

 

 

 

 

 

 

class Fu {
    private int age = 10;
    public String name = "fu";

    public Fu getObj(){
        return this;
    }
}

class Zi extends Fu {
    //'age' has private access in 'JavaBasicReview.Fu'

    public Zi(int age) {
        this.age = age;
        //super();对super()的调用必须是构造函数体中的第一个语句
    }

    private int age /*= super.age*/;
    private String name = super.name;
    private int num = this.age;

    public void show() {
        System.out.println(name);//fu
        System.out.println(num);//0
    }
    //重写方法时，必须与父类方法 具有完全相同的方法名、参数列表，返回值类型必须小于或者等于父类返回值类型
    @Override
    public Zi getObj() {
        return this;
    }
}