What are the container classes in java

Container classes in java: List(list), Set(set), Queue(queue) , Map(Map)

List (List): What we care about is the index. It is an interface, cannot instantiate objects, and can store repeated elements.

ArrayList (dynamic array):

List<String> l1=new ArrayList<String>();
			l1.add("许远志");
			l1.add("将最前");
			l1.remove(0);

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Please see the example:

//遍历
		for(String str:l1) {
			System.out.println(str);
		}
		for(int i=0;i<l1.size();i++) {
			System.out.println(l1.get(i));
		}
		//LinkedList(链表)方便数组的插入操作
		List<String> l2=new LinkedList<String>();
		l2.add("许远志");
		l2.add("许远志2");
		l2.add("许远志3");
		for(String str1:l2) {
			System.out.println(str1);
		}
		//Set(集)：关心唯一性  对象无序存储  不能存储重复元素
		Set<String> s1=new HashSet<String>();
		s1.add("xuxu");
		s1.add("yuan");
		s1.add("zhi");
		s1.remove("zhi");
		for(String str:s1) {
			System.out.println(str);
		}
		//Map(映射)对象以键-值对应存储  key不允许有重复  value允许有重复
		Map<String,String> m=new HashMap<String,String>();
		m.put("apple","苹果");
	    m.put("book","书");
	    m.put("student","学生");
	    System.out.println(m.get("apple"));		    
	     
	    for(String key :m.keySet()) {
	    	System.out.println(key+":"+m.get(key));
	    }

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