toString()方法

/*
 * Object类中toString()的使用：
 * 
 * 1.当我们输出一个对象的引用时，实际上就是调用当前对象的toString()
 * 
 * 2.Object类中toString()的定义：
 *  public String toString() {
        return getClass().getName() + "@" + Integer.toHexString(hashCode());
    }
 * 
 * 3.像String、date、File、包装类等都重写了 Object类中toString()方法。
 *   使得在调用对象的toString()时，返回“实体内容”信息
 * 
 * 4.自定义类也可以重写toString()方法，当调用此方法时，返回对象的“实体内容”
 * 
 */

package com.day0127_2;
import java.util.Date;
public class ToStringTest {
  public static void main(String[] args) {
    Customer cust1=new Customer("Tom",21);
    System.out.println(cust1.toString()); //com.day0127_2.Customer@2a139a55//重写后Customer[name =Tom,age = 21]
    System.out.println(cust1);        //com.day0127_2.Customer@2a139a55//重写后Customer[name =Tom,age = 21]
    String str = new String ("MM");
    System.out.println(str);//MM
    Date date =new Date(12823745L);
    System.out.println(date.toString());//Thu Jan 01 11:33:43 CST 1970
  }
}

package com.day0127_2;
public class Customer {
  private String name;
  private int age;
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  public int getAge() {
    return age;
  }
  public void setAge(int age) {
    this.age = age;
  }
  public Customer() {
    super();
  }
  public Customer(String name, int age) {
    super();
    this.name = name;
    this.age = age;
  }
  //手动实现
//  @Override
//  public String toString() {
//    return "Customer[name ="+name+",age = "+age+"]";
//  }
  //自动实现
  @Override
  public String toString() {
    return "Customer [name=" + name + ", age=" + age + "]";
  }
}