JAVA基础学习之路（十一）引用传递

 引用传递：

不同栈内存可以指向同一块堆内存，不同栈内存可以对一块堆内存进行修改

 

范例一：

class Message {private int num = 10;public Message(int num) {this.num = num;}public void setNum(int num) {this.num = num;}public int getNum() {return this.num;}
} public class test1 {public static void main(String args[]) {Message msg = new Message(30);fun(msg);//引用传递
        System.out.println(msg.getNum());}    public static void fun(Message temp) {temp.setNum(100);}
}
//输出  100

 

内存分析：

 

 

范例二：

public class test1 {public static void main(String args[]) {String msg = "hello";fun(msg);//引用传递
        System.out.println(msg);}    public static void fun(String temp) {temp = "world";}
}//输出：hello

输出结果仍为hello，msg的值没有被改变

原因：String类对象的内容一旦声明，则不可改变。对象内容的改变，依靠的是引用地址的改变

 

范例三：

class Message {private String info = "nihao";public Message(String info) {this.info = info;}public void setInfo(String info) {this.info = info;}public String getInfo() {return this.info ;}
} public class test1 {public static void main(String args[]) {Message msg = new Message("hello");fun(msg);//引用传递
        System.out.println(msg.getInfo());}    public static void fun(Message temp) {temp.setInfo("world");}
}//输出world

 

内存分析：

 

 

class Member {private int mid;private String name;private Member child;private Car car;public Member(int mid, String name) {this.mid = mid;this.name = name;}public String getInfo() {return "编号:"+this.mid+"\n"+"名字"+this.name;    }public void setCar(Car car) {this.car = car;    }public Car getCar() {return this.car;    }public void setChild(Member child) {this.child = child;}public Member getChild() {return this.child;}
}class Car {private Member member;private String name;public Car(String name) {this.name = name;}public String getInfo() {return "车的名字"+name;}public void setMember(Member member) {this.member = member;}public Member getMember() {return this.member;}
}public class test1 {public static void main(String args[]) {Member m = new Member(1,"张三");Member ch = new Member(2,"李四");Car c = new Car("宝马");Car cc = new Car("奔驰");m.setCar(c);c.setMember(m);ch.setCar(cc);cc.setMember(ch);m.setChild(ch);System.out.println(m.getCar().getInfo());System.out.println(c.getMember().getInfo());System.out.println(m.getChild().getCar().getInfo());}    
}