引用问题

package jdk.ref;

/**
 * @author <a href="mailto:zhangting@taobao.com">张挺</a>
 * @since 2010-4-27 10:01:45
 */
public class RefDemo {
    public static void main(String[] args) {
        A a = new A();
        System.out.println(a.b.getA());
        B b = a.getB(); //获得了引用
        b.setA(3);
        System.out.println(a.b.getA());
        b = new B(); //完全改变了引用的对象
        b.setA(5);
        System.out.println(a.b.getA());

    }
}

class A {
    B b = new B();

    public B getB() {
        return b;
    }

    public void setB(B b) {
        this.b = b;
    }
}

class B {
    int a =2;

    void setA(int a) {
        this.a = a;
    }

    int getA() {
        return this.a;
    }
}

简单放个引用问题

output：

2

3

3