iterator迭代器的使用_遍歷List和Set和Map
阿新 • • 發佈:2018-11-02
迭代器為我們提供了統一的遍歷容器的方式:
package com.jianshun; import java.util.ArrayList; import java.util.HashMap; import java.util.HashSet; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.Map.Entry; import java.util.Set; /** * 測試迭代器遍歷 List,Set,Map * @author Administrator * */ public class TestIterator { public static void main(String[] args) { //testIteratorList(); //testIteratorSet(); testIteratorMap(); } //遍歷Map public static void testIteratorMap(){ Map<Integer,String> map1 = new HashMap<Integer, String>(); map1.put(100, "aa"); map1.put(200, "bb"); map1.put(300, "cc"); //第一種遍歷Map的方式 Set<Entry<Integer,String>> ss = map1.entrySet(); for(Iterator<Entry<Integer,String>> iter = ss.iterator(); iter.hasNext();){ Entry<Integer,String> temp = iter.next(); System.out.println(temp.getKey()+"--"+temp.getValue()); } System.out.println("*********"); //第二種Map的方式 Set<Integer> keySet = map1.keySet(); for(Iterator<Integer> iter = keySet.iterator(); iter.hasNext();){ Integer key = iter.next(); System.out.println(key+"--"+map1.get(key)); } } //遍歷Set public static void testIteratorSet(){ Set<String> set = new HashSet<String>(); set.add("aa"); set.add("bb"); set.add("cc"); //使用迭代器遍歷set for(Iterator<String> iter = set.iterator(); iter.hasNext();){ String temp = iter.next(); System.out.println(temp); } } //遍歷List public static void testIteratorList(){ List<String> list = new ArrayList<String>(); list.add("aa"); list.add("bb"); list.add("cc"); //使用迭代器遍歷List for(Iterator<String> iter = list.iterator(); iter.hasNext();){ String temp = iter.next(); System.out.println(temp); } } }