使用entrySet遍历map

package test;import java.util.HashMap;import java.util.Iterator;import java.util.LinkedHashMap;import java.util.Map;import java.util.Map.Entry;public class test3 {public static void main(String[] args) {Map<String, String> map = new HashMap<>();map.put("1","2");map.put("2","3");map.put("3","4");Map<String,String> map1 = Map.of("k1", "v1", "k2", "v2", "k3", "v3");//java9引入的方法，map1集合是不可变集合，且key和value的值都不能为nullMap<String,String> map2 = new LinkedHashMap<>(Map.of("k1", "v1", "k2", "v2", "k3", "v3"));map2.put("1","2");for (Iterator<Entry<String, String>> iter = map2.entrySet().iterator();iter.hasNext();) {Entry<String, String> entry = iter.next();System.out.println("key=" + entry.getKey());System.out.println("value=" + entry.getValue());}System.out.println(map1.getClass());}}