编译器告诉我在我已经有的时候实现compareTo()方法

Question

我有以下类来实现Comparable接口.我已经在其中定义了该compareTo()方法,但不知怎的,编译器仍然告诉我必须实现它.

public class Person implements Comparable { 
    private String fName;
    private String lName;
    private Integer age;
    public Person (String fName, String lName, int age)
    {
        this.fName = fName;
        this.lName = lName;
        this.age = age;
    }

    // Compare ages, if ages match then compare last names
    public int compareTo(Person o) {
        int thisCmp = age.compareTo(o.age);        
        return (thisCmp != 0 ? thisCmp : lName.compareTo(o.Name));
    }
}

错误消息:

The type Person must implement the inherited abstract method Comparable.compareTo(Object)
Syntax error on token "=", delete this token
    at me.myname.mypkg.Person.<init>(Person.java:6)

我非常积极,我不必Object在compareTo() 方法中转换为root类.那么我可以做错什么呢？

Answer 1

添加泛型类型以匹配compareTo方法

public class Person implements Comparable<Person> { 

Answer 2

如果您要使用Generic,那么您的课程就像这样

class Person implements Comparable<Person> {

    private String fName;
    private String lName;
    private Integer age;

    public int compareTo(Person o) {
        int thisCmp = age.compareTo(o.age);        
        return (thisCmp != 0 ? thisCmp : lName.compareTo(o.fName));
     }      
}

如果您不使用Generic,那么您的课程就像

class Person implements Comparable {

    private String fName;
    private String lName;
    private Integer age;    
    public int compareTo(Object  obj) {
        Person o= (Person) obj;
        int thisCmp = age.compareTo(o.age);        
        return (thisCmp != 0 ? thisCmp : lName.compareTo(o.fName));
     }  
}