JAVA基础学习之路（十一）引用传递
2024-10-01 11:41:38
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());
}
}
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