list,set,map的几种遍历简介?

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1.list集合有3种遍历方式:
注:代码中需要导入的包这里不在给出

public void run1() {
		List<String> list = new ArrayList<>();
		list.add("美美");
		list.add("旺财");
		list.add("芙蓉街机");
		/***********************list遍历***************************/
		//1.普通for循环
		for (int i = 0; i < list.size(); i++) {
			String str = list.get(i);
			System.out.println(str);
		}
		System.out.println("========================");
		//2.foreach循环(增强for循环)
		for (String str : list) {
			System.out.println(str);
		}
		System.out.println("========================");
		//3.迭代器此处的
		Iterator<String> it = list.iterator();
		while (it.hasNext()) {
			System.out.println(it.next());
		}
	}

2.set集合有2种遍历方式

public void run2() {
		Set<String> set = new HashSet<>();
		set.add("aaa");
		set.add("bbb");
		set.add("ccc");
		set.add("ddd");
		//1.迭代器
		Iterator<String> it = set.iterator();
		while (it.hasNext()) {
			System.out.println(it.next());
		}
		System.out.println("========================");
		//2.foreach循环(增强for循环)
		for (String string : set) {
			System.out.println(string);
		}
	}

3. map集合有2中遍历方式.如图:
   

   public void run3() {
   Map<String, Integer> map = new HashMap<>();
   map.put(“aa”, 1);
   map.put(“bb”, 2);
   map.put(“cc”, 3);
   //1.通过获取keyset集合,再调用get(key)方法获取value值
   Set keys = map.keySet();
   for (String key : keys) {
   Integer value = map.get(key);
   System.out.println(key + “:” + value);
   }
   System.out.println("==================");
   //2.通过entry获取一对key value
   Set<Entry<String, Integer>> entrys = map.entrySet();
   for (Entry<String, Integer> entry : entrys) {
   System.out.println(entry.getKey()+":"+entry.getValue());
   }
   }