markdown
### 枚举 Enum
```text
有限的确定的对象
enum Temp{}
```
### 集合
```text
#单列集合，存储一个一个的对象
public interface Collection extends Iterable
#有序，可重复的对象
public interface List extends Collection
ArrayList,LinkedList,Vector
#无序，不可重复的对象
public interface Set extends Collection
HashSet,LinkedHashSet,TreeSet
#双列集合，存储一对一对的对象
public interface Map
HashMap,LinkedHashMap,TreeMap,Hashtable,Properties
```
#### 1.Collection
##### ArrayList
```text
Collection temp = new ArrayList();
temp.add(new String("hello"));
Person person = new Person(12,"name",12.2);
temp.add(person);
System.out.println(temp.contains(new Person(12, "name", 12.2)));
System.out.println(temp.contains(new String("hello")));
for (Object o : temp) {
System.out.println(o.toString());
}
temp.remove("hello");
for (Object o : temp) {
System.out.println(o.toString());
}
temp.add(23);
temp.add(3423);
Iterator iterator = temp.iterator();
while (iterator.hasNext()) {
if (iterator.next() instanceof Person)
System.out.println("是人");
}
temp.clear();
```
##### LinkedList
```text
底层使用双向链表，高效插入删除应当使用此类
```
##### Vector
```text
过于古老不建议使用
```
##### HashSet -- LinkedHashSet
```text
频繁的遍历 应当使用LinkedHashSet
```
##### TreeSet
```text
添加的数据要求是同一个类
```
#### 2.Map
#### HashMap -- LinkedHashMap TreeMap Properties
```text
Map hashMap = new HashMap();
hashMap.put(12,"harlod");
hashMap.put("name","dashwood");
System.out.println(hashMap.containsKey("name"));
Set set = hashMap.keySet();
Iterator iterator = set.iterator();
while(iterator.hasNext())
System.out.println(iterator.next());
for (Object value : hashMap.values()) {
System.out.println(value);
}
```
```text
工具类： java.util.Collections
```
### 泛型
```text
规范数据类型，保证数据的安全
```
#### 范型类
```text
class Information{
private Integer id;
private String name;
private T desc;
}
Information information = new Information();
```
#### 范型方法
```text
#在范型方法中定义的范型与类的范型无关
public List getInformation(E[] array) {
}
```
```text
List 与 List 共同父类 List
```
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