luohzzz

List集合接口的使用
特點是：有序、有下標、可以重復
1、add、remove、clear
2、list的for的遍歷、迭代器Iterator的遍歷、迭代器ListIterator的遍歷
3、contains判斷是否存在、isEmpty判斷是否為空、indexOf獲取某個元素的位置
## add、remove、clear

```java
List list = new ArrayList();
list.add("蘋果");
list.add(0,"華為");
System.out.println(list.size());//結(jié)果為2
System.out.println(list);//結(jié)果為[華為、蘋果]
list.remove(0);
list.remove("華為");
System.out.println(list);//結(jié)果為蘋果
list.clear();
System.out.println(list.size());//結(jié)果為0
```
## for的遍歷、Iterator的遍歷、ListIterator的遍歷
```java
List list = new ArrayList();
list.add("蘋果");
list.add(0,"華為");
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}//結(jié)果為[華為、蘋果]
```

```java
List list = new ArrayList();
list.add("蘋果");
list.add(0,"華為");
for (Object object : list){
System.out.println(object);
}//結(jié)果為[華為、蘋果]
```

```java
List list = new ArrayList();
list.add("蘋果");
list.add(0,"華為");
Iterator n = list.iterator();
while (n.hasNext()){
System.out.println(n.next());
}//結(jié)果為[華為、蘋果]
```

```java
List list = new ArrayList();
list.add("蘋果");
list.add(0,"華為");
ListIterator m = list.listIterator();
while (m.hasNext()){
System.out.println(m.nextIndex()+":"+m.next());
}//結(jié)果為0：華為
// 1:蘋果
```

## contains、isEmpty、indexOf
```java
List list = new ArrayList();
list.add("蘋果");
list.add(0,"華為");
System.out.println(list.contains("華為"));//結(jié)果為true
System.out.println(list.isEmpty());//結(jié)果為flase
```

```java
List list = new ArrayList();
list.add("蘋果");
list.add(0,"華為");
System.out.println(list.indexOf("華為"));//結(jié)果為0
```
注意數(shù)值！！remove時要進行拆箱??！

```java
List list = new ArrayList();
//添加數(shù)值（這里自動裝箱了！?。。?br> list.add(20);
list.add(30);
list.add(40);
list.add(50);
list.add(60);
System.out.println("元素個數(shù)："+list.size());//結(jié)果為元素個數(shù)：5
System.out.println(list);//結(jié)果為[20, 30, 40, 50, 60]

list.remove((Object) 20);//上面自動裝箱了要轉(zhuǎn)換類型進行拆箱?。。?！
System.out.println(list.size());//結(jié)果為4

//方法subList，返回子集合！含頭不含尾
List subList = list.subList(1,3);
System.out.println(subList.toString());//結(jié)果為[40, 50]
```