java集合里面LinkedList

Question

package cn.com.wangxiukai;

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

public class Test {
public static void main(String[] args) {
Entity tac=new Entity(1, "东川地震了", "大家");
Entity tar=new Entity(2, "黄河水满了", "我");

   LinkedList hehe =new LinkedList();

   hehe.addFirst(tac);
   hehe.addLast(tar);

   Entity tttt=(Entity) hehe.getFirst();
   Entity tt=(Entity) hehe.getLast();

   hehe.remove();

   for (int i = 0; i <hehe.size(); i++) {
       Entity uu=new hehe.get(i);
       //为什么会出错呀？
       System.out.println((i+1)+uu.getName());


}

}
}

Answer 1

实体类：
private String id;
private String name;
private int num;

public User(int num,String id, String name) {

    this.id = id;
    this.name = name;
    this.num = num;
}
public String getId() {
    return id;
}
public void setId(String id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public int getNum() {
    return num;
}
public void setNum(int num) {
    this.num = num;
}

测试：

User u=new User(1, "东川地震了", "大家");
User u1=new User(2, "黄河水满了", "我");
//用泛型让其记住存取类型 就如数组中User[] u=new User[5];
User[] use=new User[5];
use[0]=u;
use[1]=u1;

    LinkedList<User> llu=new LinkedList<User>();
    llu.addFirst(u);
    llu.addLast(u1);

    User ur=llu.getFirst();
    User us=llu.getLast();

    User ur1=use[0];
    User ur2=use[1];

    for(int i=0;i<llu.size();i++){
        // User为定义类型 ue为变量名  llu.get(i)拿出来的是对象 如果没有用泛型那就需要强转下
        User ue=llu.get(i);
        System.out.println((i+1)+"\t"+ue.getName()); 

    }