java集合类treemap_Java集合类中TreeMap的应用

import java.util.Comparator; import java.util.Iterator; import java.util.Set; import java.util.TreeMap; public class TreeMapTest { public static void main(String[] args) { Person p1 = new Person(100); Person p2 = new Person(70); Person p3 = new Person(90); Person p4 = new Person(60); TreeMap treeMap = new TreeMap(new MyComparator()); treeMap.put(Integer.valueOf(p1.getScore()), p1); treeMap.put(Integer.valueOf(p2.getScore()), p2); treeMap.put(Integer.valueOf(p3.getScore()), p3); treeMap.put(Integer.valueOf(p4.getScore()), p4); Set key = treeMap.keySet(); for(Iterator iterator = key.iterator(); iterator.hasNext();) { Integer keyInteger = (Integer)iterator.next(); Person person = (Person)treeMap.get(keyInteger); System.out.println(keyInteger + ":" + person.toString()); } } } class Person { private int score; public Person(int score) { this.score = score; } public int getScore() { return score; } public void setScore(int score) { this.score = score; } } //根据键自定义比较器 class MyComparator implements Comparator { @Override public int compare(Integer o1, Integer o2) { return o2.intValue() - o1.intValue(); } }