一、Map 遍历
public static void main(String[] args) { Map<String, String> map = new HashMap<String, String>(); map.put("1", "value1"); map.put("2", "value2"); map.put("3", "value3"); //第一种:普遍使用,二次取值 System.out.println("通过Map.keySet遍历key和value:"); for (String key : map.keySet()) { System.out.println("key= "+ key + " and value= " + map.get(key)); } //第二种 System.out.println("通过Map.entrySet使用iterator遍历key和value:"); Iterator<Map.Entry<String, String>> it = map.entrySet().iterator(); while (it.hasNext()) { Map.Entry<String, String> entry = it.next(); System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue()); } //第三种:推荐,尤其是容量大时 System.out.println("通过Map.entrySet遍历key和value"); for (Map.Entry<String, String> entry : map.entrySet()) { System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue()); } //第四种 System.out.println("通过Map.values()遍历所有的value,但不能遍历key"); for (String v : map.values()) { System.out.println("value= " + v); } }
二、List遍历
package com.test; import java.util.ArrayList; import java.util.Iterator; import java.util.List; public class ArrayListDemo { public static void main(String args[]){ List<String> list = new ArrayList<String>(); list.add("luojiahui"); list.add("luojiafeng"); //方法1 Iterator it1 = list.iterator(); while(it1.hasNext()){ System.out.println(it1.next()); } //方法2 for(Iterator it2 = list.iterator();it2.hasNext();){ System.out.println(it2.next()); } //方法3 for(String tmp:list){ System.out.println(tmp); } //方法4 for(int i = 0;i < list.size(); i ++){ System.out.println(list.get(i)); } } }
参考:
[1] kristain.历Map的四种方法.http://www.cnblogs.com/kristain/articles/2033566.html
[2] poppy.java 遍历arrayList的四种方法.http://blog.sina.com.cn/s/blog_6d3740cd0100mz5n.html