private ,friendly,public protected四种修饰符访问权限(从idea代码提示中看出)

时间:2021-03-17 15:10:08

private ,friendly,public protected四种修饰符访问权限(从idea代码提示中看出)

文件一,本类中可以访问全部:

package xsf;

/**
* Created by liwenj on 2017/7/25.
*/
public class A {
private int x=12;//私有
int y=1;//friendly
public int z=2;//公共
protected int m=14;//受保护

public int getX() {
return x;
}

public void setX(int x) {
this.x = x;
}
public void t(){
System.out.println(
this.y);
System.out.println(
this.z);
System.out.println(
this.m);
}
}

文件2,同一个包下面实例化的对象可以访问除 private的内容:

package xsf;

/**
* Created by liwenj on 2017/7/25.
*/
public class B {
public void t(){
A a
=new A();
System.out.println(a.y);
System.out.println(a.z);
System.out.println(a.m);
}
}

外包文件3,子类中能访问protected,public:

package xsf1;

import xsf.A;//引入xsf外包

/**
* Created by liwenj on 2017/7/25.
*/
public class B1 extends A{
public void t(){
System.out.println(
this.z);
}
}

外包文件4,只能访问public 

package xsf1;

import xsf.A;

/**
* Created by liwenj on 2017/7/25.
*/
public class B2 {
public void t(){
A a
=new A();
System.out.println(a.z);
}
}