Question

如何使用Java List等集合类的removeAll方法

Answer 1

1. 先取得list list=new list();
   

2. list.add();(一些东西)

3. list.removeall(刚才的东西全不见了)
   

Answer 2

public class User {

private String name;
private int age;

//setter and getter
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}

}

import java.util.ArrayList;
import java.util.List;

public class UserList {

private List<User> subList;
private List<User> allList;

public UserList(){
subList=new ArrayList<User>();
allList=new ArrayList<User>();

for(int i=0;i<3;i++){
User user=new User();
user.setAge(i);
user.setName("lyh"+i);
subList.add(user);
}

for(int i=0;i<10;i++){
User user=new User();
user.setAge(i);
user.setName("lyh"+i);
allList.add(user);
}
}

public static void main(String[] args){
UserList userList=new UserList();
userList.allList.removeAll(userList.subList);//调用removeAll方法

System.out.println(userList.allList.size());

}
}