java - 无需实现即可比较

Question

我是java新手。我正在学习界面，我正在尝试执行以下操作:

package comparator;
import java.io.*;
import java.util.*;

public class comparator {
    public static bankAccount ba=new bankAccount(80);
    public static void main(String args[]){
    method1(ba);
    }
    public static void method1(bankAccount ba1){
        bankAccount ba2=new bankAccount(80);
        int c=((Comparable) ba1).compareTo(ba2);
        System.out.println(c);
    }
}
class bankAccount{
    public double balance;
    public A(double bal){
        balance=bal;
    }
}

但是我收到如下错误:

Exception in thread "main" java.lang.ClassCastException: comparator.bankAccount cannot be cast to java.lang.Comparable
    at comparator.comparator.method1(comparator.java:25)
    at comparator.comparator.main(comparator.java:20)

我无法理解这种新类型的错误。任何帮助将非常感激。

Answer 1

您根本无法将 bankAccount 类型的对象转换为 Comparable。您需要在 bankAccount 类中实现 Comparable 接口(interface)并重写 compareTo() 方法。

public class bankAccount implements Comparable {
    @Override
    public int compareTo(Object o){
        // TODO Auto-generated method stub
        // Your logic goes here
        return 0;
    }
}