引用传递

引用传递的核心意义：

同一块堆内存空间可以被不同的栈内存所指向，不同的栈内存可以对同一个堆内存进行内容的修改。

实例1：

class Message {private int num = 10;public Message(int num){this.num = num;    //2.this是代表msg这个对象，num = 30
    }public void setNum(int num){this.num = num;}public int getNum(){return this.num;}
}public class Demo{public static void main(String args[]){Message msg = new Message(30);    //1.实例化Massage对象msgfun(msg);    //3.调用fun方法
        System.out.println(msg.getNum());}public static void fun(Message temp){temp.setNum(100);    //4.temp是msg，调用Massage类的setNum方法，num=100
    }
}
/*--------------------------------------------------------------
E:\Javacode>java Demo
100E:\Javacode>*/

实例2：

public class Demo{public static void main(String args[]){String msg = "hello";fun(msg);System.out.println(msg);}public static void fun(String temp){temp = "World";}
}
/*----------------------------------------------
E:\Javacode>java Demo
helloE:\Javacode>*/

实例3：

class Message {private String info = "你好";public Message(String info){this.info = info;}public void setInfo(String info){this.info = info;}public String getInfo(){return this.info;}
}public class Demo{public static void main(String args[]){Message msg = new Message("hello");fun(msg);System.out.println(msg.getInfo());}public static void fun(Message temp){temp.setInfo("world");}
}
/*------------------------------------------
E:\Javacode>java Demo
worldE:\Javacode>*/