java中Comparator有什么用，举例说明

3.6 Comparator的用法  

马克-to-win：和Comparable的思路一样，只不过排序规则这次是在Comparator的继承类的compare方法中定义。

例：3.6.1

import java.util.*;

// A reverse comparator for strings.

class MyComp implements Comparator {

    /* Comparator has two methods compare and equals, when your class implements

      Comparator, there is no need to override equals, why? java.lang Class

      Object implement equals method, so its sub-class MyComp does not need to

      implement equals method, while java.lang Class Object does not implements

      compare mathod.     */

    public int compare(Object a, Object b) {

        String aStr, bStr;

        aStr = (String) a;

        bStr = (String) b;

        /* compareTo(String anotherString)Compares two strings

         * lexicographically. The comparison is based on the Unicode value of

         * each character in the strings. The character sequence represented by

         * this String object is compared lexicographically to the characte

         * sequence represented by the argument string.

         * The result is a negative integer if this String object

         * lexicographically precedes the argument string.

         */

        /* the following two statements will have the opposite effect. */

        // return bStr.compareTo(aStr);

        return aStr.compareTo(bStr);

    }

}

public class TestMark_to_win {

    public static void main(String args[]) {

        /* Constructs a new, empty set, sorted according to the specified

         * comparator. All elements inserted into the set must be mutually

         * comparable by the specified comparator: comparator.compare(e1, e2)

         */

        TreeSet ts = new TreeSet(new MyComp());

        // Add elements to the tree set

        ts.add("C");

        ts.add("A");

        ts.add("B");

        ts.add("E");

        ts.add("F");

        ts.add("D");

        // Get an iterato

       // Get an iterato

        Iterator i = ts.iterator();

        // Display elements

        while (i.hasNext()) {

            Object element = i.next();

            System.out.print(element + " ");

        }

        System.out.println();

    }

}

更多请见：https://blog.csdn.net/qq_44639795/article/details/103087154