package test2; import java.util.*; import static java.lang.System.out; public class test2 extends StaticSuper{ //put输入,get,得到 static void mapTest(){ // TODO 自动生成的方法存根 HashMap<String, String> map = new HashMap<String, String>(); map.put("1", "a1"); map.put("2", "a2"); map.put("3", "a3"); //遍历的方法一、缺点,费时 Iterator<String> iterator = map.keySet().iterator() ; while (iterator.hasNext()){ //Object key = iterator; Object key = iterator.next(); System.out.print("Key = " + key); System.out.println(", Value = "+map.get(key)); //iterator.next(); } //遍历的方法二,省时 Iterator entries = map.entrySet().iterator(); while(entries.hasNext()){ Map.Entry entry = (Map.Entry) entries.next(); Object key = entry.getKey(); Object value = entry.getValue(); System.out.println("Key = " + key + ", Value = " + value); } System.out.println("map end!"); } static void setTest(){ Set<String> set1 = new HashSet<String>(); set1.add("s1_1"); set1.add("s1_2"); set1.add("s1_3"); set1.add("one"); System.out.println(set1); Set<String> set2 = new HashSet<String>(); set2.add("s2_1"); set2.add("s2_1"); set2.add("s2_3"); set2.add("one"); System.out.println(set2); Set<String> sn = new HashSet<String>(set1); sn.retainAll(set2); System.out.println(sn); } public static void main(String[] args) { } }