我不明白为什么我的“可比较”界面无法正常工作

Question

I am trying to implement comparable in order to use the Arrays.sort(array) but for some reason its not finding the compareTo method in the super class. I am trying to compare strings FYI.

Edit: Sorry I forgot to add the error I am getting. Here it is:

Employee.java:32: error: cannot find symbol     
return super.compareTo((Object)other);
            ^
symbol: method compareTo(Object)

Code:

public abstract class Employee implements Cloneable, Comparable
{
private Name name;
private double weeklyPay;
public Employee(String first, String middle, String last, double weeklyPay)
{
    this.weeklyPay = weeklyPay;
    name = new Name(first,middle,last);
}
public Employee(String last, double weeklyPay)
{
    this.name = name;
    this.weeklyPay = weeklyPay;
    name = new Name(last);
}
public Employee(String first, String last, double weeklyPay)
{
    this.name = name;
    this.weeklyPay = weeklyPay;
    name = new Name(first,last);
}

public abstract double getWeeklyPay();

public String getFullName()
{
    return name.getFullName();
}

public int compareTo(Object other)
{
    return super.compareTo((Object)other);
}

public int compareTo(Name name)
{
    return compareTo((Object)name.getFullName());
}

Answer 1

java.lang.Object , which is your superclass, does not implement Comparable . You should change the signature of your class to:

public abstract class Employee implements Cloneable, Comparable<Employee>

And then implement this method:

public int compareTo(Employee other) {
    // logic to compare here
}

With actual logic to do the comparison (aka, don't try and depend on some other objects implementation).

Answer 2

Comparable is an interface , and it therefore has no default implementation. Your class does not extend any other class , which means that it is not inheriting any implementation(s) either.

super.compareTo(...) will always fail in this way as a result, unless you extend another class that provides an implementation.

Answer 3

我认为您确实想编写不同的比较器，每个要比较的字段之一：名称，等等。

Answer 4

The problem is you are attempting to call super.compareTo( Object object) but because your class Employee does not itself extend a class, it will be looking for the compareTo method in Object and Object does not have that method. You need to actually implement the compareTo functionality within Employee.