如何在Java中为TreeMap编写自定义比较器？

import java.util.Comparator;
import java.util.TreeMap;

public class TreeMapComparatorExample {
    public static void main(String[] args) {
        TreeMap<MyObject, String> treeMap = new TreeMap<>(new MyComparator());

        MyObject obj1 = new MyObject("key1");
        MyObject obj2 = new MyObject("key2");
        MyObject obj3 = new MyObject("key3");

        treeMap.put(obj1, "Value 1");
        treeMap.put(obj2, "Value 2");
        treeMap.put(obj3, "Value 3");

        for (MyObject key : treeMap.keySet()) {
            System.out.println(key + " : " + treeMap.get(key));
        }
    }

    static class MyObject {
        private String key;

        public MyObject(String key) {
            this.key = key;
        }

        public String getKey() {
            return key;
        }

        @Override
        public String toString() {
            return key;
        }
    }

    static class MyComparator implements Comparator<MyObject> {
        @Override
        public int compare(MyObject obj1, MyObject obj2) {
            // 比较两个对象的key属性
            return obj1.getKey().compareTo(obj2.getKey());
        }
    }
}