package com.org.sxt.overload;
public class OverLoad {
public static void main(String[] args){
Person p = new Person();
Person p1 = new Person(2);
Person p2 = new Person(3,22);
}
}
class Person{
int id;
int age;
Person(){
id = 1;
age = 20;
}
Person(int _id){
id = _id;
age = 21;
}
Person(int _id, int _age){
id = _id;
age = _age;
}
}
这是个重载，现在想打印出p，p1，p2，应该怎么写啊？
------解决方案--------------------
- Java code
package com.org.sxt.overload;public class OverLoad { public static void main(String[] args) { Person p = new Person(); Person p1 = new Person(2); Person p2 = new Person(3, 22); System.out.println("p: " + p); System.out.println("p1: " + p1); System.out.println("p2: " + p2); }}class Person { int id; int age; Person() { id = 1; age = 20; } Person(int _id) { id = _id; age = 21; } Person(int _id, int _age) { id = _id; age = _age; } public String toString() { return "Person id=" + id + " age=" + age; }}
------解决方案--------------------
在Person中重写toString()方法
public String toString(){
return "this.id = " + this.id + " this.age=" + this.age;
}
然后在main(）方法中
System.out.println(p.toString);
System.out.println(p1.toString);
System.out.println(p2.toString);
------解决方案--------------------
原理就是在下面语句中
System.out.println("p: " + p);
计算"p: " + p时会自动调用p.toString()
等价于
"p: " + p.toString()
如果这样写System.out.println(p);
也等价于
System.out.println(p.toString());