如何打印

怎么打印？
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？

[解决办法]

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;    }}
[解决办法]
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);
[解决办法]
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());