protected/public/prevate/默认

package oo.day05;

public class Foo {
public int a; //任何类
protected int b; //本类、子类、同包类
int c; //本类、同包类
private int d; //本类

void show(){
a = 1;
b = 2;
c = 3;
d = 4;
}
}

class Goo{ //演示private
void show(){
Foo o = new Foo();
o.a = 1;
o.b = 2;
o.c = 3;
//o.d = 4; //编译错误，只能本类
}
}