1,List
2,Set
3,Map
- package com.an.collection;
- import java.util.*;
- import java.util.Map;
- /**
- * @description:
- * @author: anpeiyong
- * @date: Created in 2020/3/4 9:30
- * @since:
- */
- public class MapTest {
- public static void main(String[] args) {
- // iteratorTest();
- // iteratorTest2();
- // foreachTest();
- // foreachTest2();
- // foreachMethodTest();
- valuesTest();
- }
- public static void iteratorTest(){
- HashMap<String,String> map=new HashMap<>();
- map.put("1","a");
- map.put("2","b");
- map.put("3","c");
- Set<String> keySet=map.keySet();
- Iterator<String> iterator =keySet.iterator();
- while (iterator.hasNext()){
- String key=iterator.next();
- System.out.println(map.get(key));
- }
- }
- public static void iteratorTest2(){
- HashMap<String,String> map=new HashMap<>();
- map.put("1","a");
- map.put("2","b");
- map.put("3","c");
- Set<Map.Entry<String,String>> entrySet=map.entrySet();
- Iterator<Map.Entry<String,String>> entryIterator=entrySet.iterator();
- while (entryIterator.hasNext()){
- Map.Entry<String,String> entry=entryIterator.next();
- String key=entry.getKey();
- String value=entry.getValue();
- System.out.println(key+":"+value+"==");
- }
- }
- public static void foreachTest(){
- HashMap<String,String> map=new HashMap<>();
- map.put("1","a");
- map.put("2","b");
- map.put("3","c");
- Set<String> keySet=map.keySet();
- for (String s:keySet) {
- System.out.println(map.get(s));
- }
- }
- public static void foreachTest2(){
- HashMap<String,String> map=new HashMap<>();
- map.put("1","a");
- map.put("2","b");
- map.put("3","c");
- Set<Map.Entry<String,String>> entrySet=map.entrySet();
- for (Map.Entry<String,String> s:entrySet) {
- System.out.println(s.getKey()+":"+s.getValue());
- }
- }
- public static void foreachMethodTest(){
- HashMap<String,String> map=new HashMap<>();
- map.put("1","a");
- map.put("2","b");
- map.put("3","c");
- map.forEach((k,v)->{
- System.out.println(k+":"+v);
- });
- }
- public static void valuesTest(){
- HashMap<String,String> map=new HashMap<>();
- map.put("1","a");
- map.put("2","b");
- map.put("3","c");
- Collection<String> collection =map.values();
- System.out.println(collection);
- }
- }
来源: http://www.bubuko.com/infodetail-3446342.html