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 l1=new ArrayList(); 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 l2=new LinkedList(); 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 s1=new HashSet(); 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 m=new HashMap(); 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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