介绍List接口常用方法。
List常用方法如下：
| 方法名字 | 说明 |
|---|---|
| size() | 获取长度 |
| add(Object element) | 添加元素 |
| add(int index,Object element) | 指定位置插入元素 |
| subList(int start,int end) | 获取子集合 |
| remove(Object element) | 删除元素(仅仅删除符合条件的第一个元素) |
| remove(int index) | 删除指定索引的元素 |
| removeAll(Collection list) | 删除所有指定的元素 |
| contains(Object obj) | 判断指定元素是否存在 |
| toArray() | 序列转换为数组 |
| isEmpty() | 判断序列是否为空 |
| clear() | 清空序列 |
通过一个实例理解以上所有方法：
class Students{
private String name;
private String gender;
private int age;
public Students(String name, String gender, int age) {
this.name = name;
this.gender = gender;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "Students{" +
"name='" + name + '\'' +
", gender='" + gender + '\'' +
", age=" + age +
'}';
}
}
public class Test2 {
public static void main(String[] args) {
List list = new LinkedList();
Students s1 = new Students("张三","男",20);
Students s2 = new Students("李四","女",18);
Students s3 = new Students("王五","男",20);
Students s4 = new Students("赵六","女",22);
System.out.println("----------添加元素-----------");
list.add(s1);
list.add(s2);
list.add(s3);
list.add(s1);
list.add(s4);
System.out.println("序列长度是："+list.size());
for(Object obj : list){
System.out.println(obj);
}
System.out.println("----------指定位置插入新元素-----------");
list.add(1,new Students("王大锤","男",19));
for(Object obj : list){
System.out.println(obj);
}
System.out.println("----------获取子集合--------");
List subList = list.subList(1,list.size());
for(Object obj : subList){
System.out.println(obj);
}
System.out.println("-------------删除元素------------");
list.remove(s1); //删除张三对象，仅仅删除掉第一个张三对象
//list.removeAll(Arrays.asList(new Students[]{s1})); //删除所有的张三对象
for(Object obj : list){
System.out.println(obj);
}
System.out.println(list.contains(s4));
System.out.println(Arrays.toString(list.toArray()));
System.out.println(list.isEmpty());
list.clear();
System.out.println(list.isEmpty());
}
}
运行结果：
----------添加元素-----------
序列长度是：5
Students{name='张三', gender='男', age=20, birthday='null'}
Students{name='李四', gender='女', age=18, birthday='null'}
Students{name='王五', gender='男', age=20, birthday='null'}
Students{name='张三', gender='男', age=20, birthday='null'}
Students{name='赵六', gender='女', age=22, birthday='null'}
----------指定位置插入新元素-----------
Students{name='张三', gender='男', age=20, birthday='null'}
Students{name='王大锤', gender='男', age=19, birthday='null'}
Students{name='李四', gender='女', age=18, birthday='null'}
Students{name='王五', gender='男', age=20, birthday='null'}
Students{name='张三', gender='男', age=20, birthday='null'}
Students{name='赵六', gender='女', age=22, birthday='null'}
----------获取子集合--------
Students{name='王大锤', gender='男', age=19, birthday='null'}
Students{name='李四', gender='女', age=18, birthday='null'}
Students{name='王五', gender='男', age=20, birthday='null'}
Students{name='张三', gender='男', age=20, birthday='null'}
Students{name='赵六', gender='女', age=22, birthday='null'}
-------------删除元素------------
Students{name='王大锤', gender='男', age=19, birthday='null'}
Students{name='李四', gender='女', age=18, birthday='null'}
Students{name='王五', gender='男', age=20, birthday='null'}
Students{name='张三', gender='男', age=20, birthday='null'}
Students{name='赵六', gender='女', age=22, birthday='null'}
true
[Students{name='王大锤', gender='男', age=19, birthday='null'}, Students{name='李四', gender='女', age=18, birthday='null'}, Students{name='王五', gender='男', age=20, birthday='null'}, Students{name='张三', gender='男', age=20, birthday='null'}, Students{name='赵六', gender='女', age=22, birthday='null'}]
false
true