实现界面

Question

你好伙计,所以我有这个任务,我需要实现接口来遍历ArrayList并对其进行排序(升序或降序).我不想要"答案"我只需要一些关于我的方法的建议以及为什么我得到这个错误

Exception in thread "main" java.lang.ClassCastException: Week7.Check cannot be cast to java.lang.Comparable
 at java.util.Arrays.mergeSort(Unknown Source)
 at java.util.Arrays.sort(Unknown Source)
 at java.util.Collections.sort(Unknown Source)
 at Week7.TestCheck.main(TestCheck.java:18)

这就是我做到的方式:

比较有一种叫做的方法public int compairTo(Object o):

public class Check implements comparable {
    private Integer checkNumber;

    public Check(Integer newCheckNumber) {
        setCheckNumber(newCheckNumber);
    }

    public String toString() {
        return getCheckNumber().toString();
    }

    public void setCheckNumber(Integer checkNumber) {
        this.checkNumber = checkNumber;
    }

    public Integer getCheckNumber() {
        return checkNumber;
    }

    @Override
    public int compairTo(Object o) {
        Check compair = (Check) o;
        int result = 0;
        if (this.getCheckNumber() > compair.getCheckNumber())
            result = 1;

        else if (this.getCheckNumber() < compair.getCheckNumber())
            result = -1;

        return result;
    }
}

在我的主要我有这个

import java.util.ArrayList;
import java.util.Collections;

public class TestCheck {
    public static void main(String[] args) {
        ArrayList checkList = new ArrayList();

        checkList.add(new Check(445));
        checkList.add(new Check(101));
        checkList.add(new Check(110));
        checkList.add(new Check(553));
        checkList.add(new Check(123));

        Collections.sort(checkList);

        for (int i = 0; i < checkList.size(); i++) {
            System.out.println(checkList.get(i));
        }
    }
}

Answer 1

来吧 - Java区分大小写."可比"与"可比"不同

public class Check implements comparable

拼写也很重要."compairTo"与"compareTo"的方法不同

@Override
public int compairTo(Object o) {