面向对象进阶篇10-toString()方法

1、输出一个对象的引用时，实际上就是调用当前对象的toString()

Customer cust1 = new Customer();

System. out .println(cust1.toString());//com.exer2.lele.Customer@2752f6e2

System. out .println(cust1);//com.exer2.lele.Customer@2752f6e2

2、Object类中toStrin()的定义

public String toString() {

return getClass().getName() + "@" + Integer. toHexString (hashCode());

}

3、String、Date、File、包装类等都重写了Object类的toString()方法，当调用对象的toString()时，返回“实体内容信息”

String str = new String("apple");

System. out .println(str);//apple

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”

代码示例：

@Override

public String toString() {

return "Customer[name = " + name  + ", age = "+ age +"]";

}

Customer cust1 = new Customer("tom", 21);

System. out .println(cust1.toString());//重写前：com.exer2.lele.Customer@2752f6e2

System. out .println(cust1);//重写后：Customer[name = tom, age = 21]

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