java基础—自定义一个比较器，对TreeSet 集合中的元素按指定方法来排序(java集合六)

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自定义一个比较器，对TreeSet 集合中的元素按指定方法来排序

import java.util.Comparator;import java.util.Iterator;import java.util.TreeSet;//自定义一个比较器class Mycompare implements Comparator{@Overridepublic int compare(Object o1, Object o2) {// TODO Auto-generated method stubMinStudent ms1=(MinStudent )o1;MinStudent ms2=(MinStudent )o2;int i=ms1.getName().compareTo(ms2.getName());if(i==0)return ms1.getAge()-ms2.getAge();return i;}}public class MyCompareDemos {public static void main(String[] args) {// TODO Auto-generated method stubTreeSet ts = new TreeSet(new Mycompare());ts.add(new MinStudent("ccc",22));ts.add(new MinStudent("ddd",22));ts.add(new MinStudent("aaa",21));ts.add(new MinStudent("dad",23));ts.add(new MinStudent("fff",25));ts.add(new MinStudent("sss",22));ts.add(new MinStudent("jjj",20));Iterator it = ts.iterator();while(it.hasNext()){MinStudent ms = (MinStudent)it.next();System.out.println(ms.toString());}}}

class MinStudent implements Comparable{public int getName;private String name ;private int age;MinStudent(String name ,int age){this.name =  name ;this.age=age;}public int getAge(){return age;}public String getName(){return name;}public String toString(){return "name:"+name +" --- age"+age;}@Overridepublic int compareTo(Object o) {// MinStudent s =(MinStudent) o;//先按照年龄排序int i=this.getAge()-s.getAge();if(i ==0)return this.getName().compareTo(s.getName());return i;}}

未使用比较器前，集合中的元素顺序是》

使用比较器后：

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