map
public static void main(String[] args) {// 构建一个Map 初始值为3条数据Map<String, String> map = new HashMap<String, String>();map.put("1", "xiaqiu");map.put("2", "pangzi");map.put("3", "shouzi");//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:通过Iterator迭代器遍历循环Map.entrySet().iterator();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:笔者推荐,尤其是容量大时(相对来说 比2好一点 效率高)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);}}
set
1.迭代遍历: Set<String> set = new HashSet<String>(); Iterator<String> it = set.iterator(); while (it.hasNext()) {String str = it.next(); System.out.println(str); } 2.for循环遍历: for (String str : set) {System.out.println(str); }
参考链接:/magicya/p/6683052.html
参考链接:/XQiu/p/5087961.html
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