Test whether there is a comparator during initialization of TreeSet and treemap

import java.util.*;

public class testCode  {

public static void main(String[] args){
    /**
     * (1)TreeSet里面:没有接口Comparator中的compare<a href="https://www.jb51.cc/tag/fangfa/" target="_blank" class="keywords">方法</a>,只<a href="https://www.jb51.cc/tag/diaoyong/" target="_blank" class="keywords">调用</a>了接口Comparator中的equals<a href="https://www.jb51.cc/tag/fangfa/" target="_blank" class="keywords">方法</a>
     * (2)继承了抽象类AbstractSet<E>:equals<a href="https://www.jb51.cc/tag/fangfa/" target="_blank" class="keywords">方法</a>被覆写.故TreeSet<a href="https://www.jb51.cc/tag/diaoyong/" target="_blank" class="keywords">调用</a>equals<a href="https://www.jb51.cc/tag/fangfa/" target="_blank" class="keywords">方法</a>时,是<a href="https://www.jb51.cc/tag/diaoyong/" target="_blank" class="keywords">调用</a>的这个equals<a href="https://www.jb51.cc/tag/fangfa/" target="_blank" class="keywords">方法</a>.
     */
    //例一:TreeSet在初始化时,指定比较器,从而指定元素的排列顺序
    TreeSet<Integer> set=new TreeSet<Integer>(new Comparator<Integer>() {
        @Override
        public int compare(Integer o1,Integer o2) {
            return o2-o1;//降序
        }
    });
    set.add(1);set.add(4);set.add(3);

    //例二:TreeSet在初始化时,不指定比较器,故元素的排列顺序为<a href="https://www.jb51.cc/tag/mo/" target="_blank" class="keywords">默</a>认的升序
    TreeSet<Integer> set1=new TreeSet<Integer>();
    set1.add(1);set1.add(4);set1.add(3);

    //分别<a href="https://www.jb51.cc/tag/shuchu/" target="_blank" class="keywords">输出</a>set,set1
    Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println("set: ");
    Iterator<Integer> iterator1=set.iterator();
    while (iterator1.hasNext()){
        Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.print(iterator1.next()+" ");
    }
    Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println();
    Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println("---------------------");


    Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println("set1: ");
    Iterator<Integer> iterator2=set1.iterator();
    while (iterator2.hasNext()){
        Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.print(iterator2.next()+" ");
    }
    Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println();
    Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println("---------------------");




    /**
     * (1)TreeMap里面:没有接口Comparator中的compare<a href="https://www.jb51.cc/tag/fangfa/" target="_blank" class="keywords">方法</a>,只<a href="https://www.jb51.cc/tag/diaoyong/" target="_blank" class="keywords">调用</a>了接口Comparator中的equals<a href="https://www.jb51.cc/tag/fangfa/" target="_blank" class="keywords">方法</a>
     * (2)继承了抽象类AbstractMap<K,V>:equals<a href="https://www.jb51.cc/tag/fangfa/" target="_blank" class="keywords">方法</a>被覆写.故TreeMap<a href="https://www.jb51.cc/tag/diaoyong/" target="_blank" class="keywords">调用</a>equals<a href="https://www.jb51.cc/tag/fangfa/" target="_blank" class="keywords">方法</a>时,是<a href="https://www.jb51.cc/tag/diaoyong/" target="_blank" class="keywords">调用</a>的这个equals<a href="https://www.jb51.cc/tag/fangfa/" target="_blank" class="keywords">方法</a>.
     */
    //例一:TreeMap初始化时,未指定比较器,<a href="https://www.jb51.cc/tag/mo/" target="_blank" class="keywords">默</a>认按照key升序
    TreeMap<Integer,Integer> map=new TreeMap<Integer,Integer>();
    map.put(1,1);map.put(2,3);map.put(-1,3);map.put(4,3);

    //例二:TreeMap初始化时,指定了比较器,按照key降序
    TreeMap<Integer,Integer> map1=new TreeMap<Integer,Integer>(new Comparator<Integer>() {
        @Override
        public int compare(Integer o1,Integer o2) {
            return o2-o1;//降序
        }
    });
    map1.put(1,1);map1.put(2,3);map1.put(-1,3);map1.put(4,3);

    //<a href="https://www.jb51.cc/tag/shuchu/" target="_blank" class="keywords">输出</a>map,map1
    Iterator<Map.Entry<Integer,Integer>> i1=map.entrySet().iterator();
    Iterator<Map.Entry<Integer,Integer>> i2=map1.entrySet().iterator();

    Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println("map:");
    while (i1.hasNext()){
        Map.Entry<Integer,Integer> entry=i1.next();
        Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.print("key:"+entry.getKey()+",");
        Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println("value: "+entry.getValue());
    }
    Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println("---------------------");


    Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println("map1: ");
    while (i2.hasNext()){
        Map.Entry<Integer,Integer> entry=i2.next();
        Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.print("key: "+entry.getKey()+",");
        Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println("value: "+entry.getValue());
    }
    Sy<a href="https://www.jb51.cc/tag/stem/" target="_blank" class="keywords">stem</a>.out.println("---------------------");
}



    }


Process finished with exit code 0