java练习题之List（ArrayList）集合练习

List集合

习题：

1：完成以下填空：

List 接口的特点是元素? 有序 （有|无）顺序，? 可重复 （可以|不可以）重复；

2：(List)关于List 集合描述正确的是（）

A.可以利用List 直接创建集合对象，用于存储多个数据

B.List 集合可以利用下标操作集合中的元素

C.Collection 是List 的父接口(正确)

D.List 中的功能方法全部继承于父接口

3：(List)欲构造ArrayList 类的一个实例，此类继承了 List 接口，下列哪个方法是正确的（）

ArrayList myList = new Object();?顶级父类

List myList = new ArrayList();

ArrayList myList = new List();

List myList = new List();

4：(List)仔细阅读以下代码，写出程序运行的结果。

Hello

Learn

5：(List)简单介绍ArrayList、LinkedList、Vector 的特性及区别。

ArrayList底层是数组结构 ?所以他是有序的 ?查询快，增删慢 ?线程不安全,效率高

LinkedList底层是链表结构 ??查询慢 ?增删快 ??线程不安全,效率高

Vector 底层数组实现?都慢 线程安全,效率低

6：(List)简述List<String> list1= new ArrayList<String>()；和List list2 =new ArrayList()；区别及

<String>的作用。

List<String> 有泛型约束，是他只能存放String类型的元素，更加的安全

list没有泛型约束，可以存放不同类型的元素，放的更多，越不安全，有时需要进行类型强转

使类型安全，代码清晰，具有向后兼容性，不用进行类型强转，更加的方便

7：(List)编程：创建一个工人类，属性：姓名、年龄、工资，要求如下：

①为Worker 提供无、有参数的构造方法，属性私有，并提供公开的 get/set

②创建多个Worker 类，存储在List 集合中。

③打印输出所有的工人信息。

④计算所有工人的平均工资。

⑤打印输出姓名中包含 "胡" 的所有工人信息。

⑥打印输出所有姓 "胡" 的工人信息。

⑦键盘输入一个姓名，查找是否存在此员工，存在，则打印输出员工的信息， 如果不存在，则输出"查 无此人"

⑧输入一个工资，查询工资 大于 输入工资的员工信息。

package com.by.homework3;

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

public class Worker {
????private String name;
????private int age;
????private double salary;

????public Worker() {
????}

????public Worker(String name, int age, double salary) {
????????this.name = name;
????????this.age = age;
????????this.salary = salary;
????}

????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;
????}

????public double getSalary() {
????????return salary;
????}

????public void setSalary(double salary) {
????????this.salary = salary;
????}
????public String toString(){
????????return "姓名:"+name+",年龄:"+age+",薪资:"+salary;
????}
}

class WorkTest{
????public static void main(String[] args) {
????????List<Worker> list = new ArrayList<>();
????????list.add(new Worker("张三", 18, 2000));
????????list.add(new Worker("李四", 19, 3000));
????????list.add(new Worker("王五", 20, 4000));
????????list.add(new Worker("赵胡麻", 21, 5000));
????????list.add(new Worker("胡八一", 22, 6000));
????????list.forEach(o -> System.out.println(o + " "));

????????System.out.println();
????????System.out.println();
????????System.out.println("---------------------------");

????????double average = 0;
????????for (int i = 0; i<list.size(); i++){
????????????average+=list.get(i).getSalary();
????????????String s=String.valueOf(list.get(i));
????????????if (s.contains("胡")){
????????????????System.out.println(list.get(i));
????????????}
????????}
????????System.out.println();
????????System.out.println("平均工资为："+average/5);
????????String string=String.valueOf(list);
????????char []chars=string.toCharArray();
????????for (int i = 0; i < chars.length; i++) {
????????????if (String.valueOf(chars[i]).equals("胡")){
????????????????System.out.println(chars[i]);
????????????}
????????}

????????Scanner sc=new Scanner(System.in);
????????System.out.println("请输入名字");
????????String s1=sc.next();
????????boolean boo=false;
????????for (int i=0;i<list.size();i++){
????????????if(s1.equals(list.get(i).getName())){
????????????????System.out.println(list.get(i));
????????????????boo=true;
????????????}
????????}
????????if (!boo){
????????????System.out.println("不存在");
????????}
????????System.out.println("请输入工资");
????????double d=sc.nextInt();
????????for (int i=0;i<list.size();i++){
????????????if(d<list.get(i).getSalary()){
????????????????System.out.println(list.get(i));
????????????????boo=true;
????????????}
????????}
????????if (!boo){
????????????System.out.println("不存在");
????????}
????}
}

8：(List)编程：已知有 Worker 类，属性为姓名、年龄、工资，完成类的封装并提供无参数、有参数构造方法，完成以下要求：

①创建一个List，在List 中增加三个工人，基本信息如下 :

姓名 年龄 工资

zhang3 18 3000

li4 25 3500

Wang5 22 3200

②在li4 之前插入一个工人，信息为：姓名：zhao6，年龄：24，工资 3300

③删除wang5 的信息

④利用下标遍历，打印输出所有工人信息

⑤利用forEach 遍历，打印输出所有年龄大于 20 的工人信息

⑥对Worker 类添加eqauls 方法

package com.by.homework3;

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

public class Worker1 {
????private String name;
????private int age;
????private double salary;

????public Worker1() {
????}

????public Worker1(String name, int age, double salary) {
????????this.name = name;
????????this.age = age;
????????this.salary = salary;
????}

????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;
????}

????public double getSalary() {
????????return salary;
????}

????public void setSalary(double salary) {
????????this.salary = salary;
????}

????public String toString() {
????????return "姓名:" + name + ",年龄:" + age + ",薪资:" + salary;
????}

????public boolean equals(Object o) {
????????if (this == o) {
????????????return true;
????????}
????????if (this.getClass() != o.getClass() || o.getClass() == null) {
????????????return false;
????????}
????????return this.name.equals(((Worker1) o).name);
????}
}
????class WorkerTest1 {
????????public static void main(String[] args) {
????????????List list = new ArrayList();
????????????list.add(new Worker1("zhang3", 18, 3000));
????????????list.add(new Worker1("li4", 25, 3500));
????????????list.add(new Worker1("wang5", 22, 3200));
????????????list.add(1, new Worker1("zhao6", 24, 3300));
????????????list.remove(3);
????????????for (int i = 0; i < list.size(); i++) {
????????????????System.out.println(list.get(i));
????????????}
????????????System.out.println();
????????????System.out.println("--------------------------");
????????????for (Object w : list) {
????????????????Worker1 worker1 = (Worker1) w;
????????????????if (worker1.getAge() > 20) {
????????????????????System.out.println(w);
????????????????}
????????????}
????????}

}

9：（List）?创建一个商品(Produtor)类,属性：商品名，商品单价，商品的数量，商品产地。

???? ① 创建多个商品对象，存储在List集合中。

② 显示所有的商品信息。

③ 打印输出商品价格 > 1000 的所有商品信息。

④ 打印售空的商品的信息。

⑤ 打印输出商品产地为"北京"的商品信息。

⑥ 输入一个商品名，查询出此类商品的信息，如果不存在，则打印商品"商场无此商品！！！"

⑦ 输入一个价格段，查询出集合中所有在这个价格区间的所有商品信息。

package com.by.homework3;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.function.Consumer;

public class Produtor {
????private String name;
????private double price;
????private int num;
????private String production;

????public Produtor() {
????}

????public Produtor(String name, double price, int num, String production) {
????????this.name = name;
????????this.price = price;
????????this.num = num;
????????this.production = production;
????}

????public String getName() {
????????return name;
????}

????public void setName(String name) {
????????this.name = name;
????}

????public double getPrice() {
????????return price;
????}

????public void setPrice(double price) {
????????this.price = price;
????}

????public int getNum() {
????????return num;
????}

????public void setNum(int num) {
????????this.num = num;
????}

????public String getProduction() {
????????return production;
????}

????public void setProduction(String production) {
????????this.production = production;
????}
????public String toString(){
????????return "商品名："+name+",价格："+price+",数量："+num+",产地："+production;
????}
}






class ProdutorTest{
????public static void main(String[] args) {
????????List list=new ArrayList();
????????list.add(new Produtor("小米",4999,99,"北京"));
????????list.add(new Produtor("红米",999,88,"杭州"));
????????list.add(new Produtor("华为",6999,0,"北京"));
????????list.add(new Produtor("苹果",10099,9999,"America"));
????????list.add(new Produtor("杂牌",100,999999,"华强北"));

????????list.forEach(new Consumer() {
????????????@Override
????????????public void accept(Object o) {
????????????????System.out.println(o+"");
????????????}
????????});

????????System.out.println();
????????System.out.println("------------");

????????for (int i=0;i<list.size();i++){
????????????Produtor produtor=(Produtor) list.get(i);
????????????if (produtor.getPrice()>1000){
????????????????System.out.println(produtor);
????????????}

????????}
????????System.out.println();
????????for (int i=0;i<list.size();i++){
????????????Produtor produtor=(Produtor) list.get(i);
????????????if (produtor.getNum()==0){
????????????????System.out.println("售空产品为："+produtor);
????????????}
????????????if(produtor.getProduction().equals("北京")){
????????????????System.out.println(produtor);
????????????}

????????}

????????System.out.println();
????????for (int i=0;i<list.size();i++){
????????????Produtor produtor=(Produtor) list.get(i);

????????????if(produtor.getProduction().equals("北京")){
????????????????System.out.println(produtor);
????????????}

????????}


????????Scanner scanner=new Scanner(System.in);
????????System.out.println("请输入商品名：");
????????String name=scanner.next();
????????boolean boo=false;
????????for (int i=0;i<list.size();i++){
????????????Produtor produtor=(Produtor) list.get(i);
????????????if (produtor.getName().equals(name)){
????????????????System.out.println(produtor);
????????????????boo=true;
????????????}
????????}
????????if (!boo){
????????????System.out.println("不存在");
????????}
????????System.out.println("输入低价");

????????double price1=scanner.nextInt();
????????System.out.println("输入高价");
????????double price2=scanner.nextInt();
????????for (int i=0;i<list.size();i++){
????????????Produtor produtor=(Produtor) list.get(i);
????????????if (produtor.getPrice()>=price1&&produtor.getPrice()<=price2){
????????????????System.out.println(produtor);
????????????}

????????}

????}
}

10：（List）定义一个用户类(User)：---要求封装

① 属性：用户名、密码、是否在线(是-true)

② 提供有参数、无参数的构造方法

③ 创建多个对象，存储在集合中，并统计在线用户数量，打印在控制台上。

package com.by.homework3;

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

public class User {
????private String name;
????private String password;
????private boolean zaixian;

????public User() {
????}

????public User(String name, String password, boolean zaixian) {
????????this.name = name;
????????this.password = password;
????????this.zaixian = zaixian;
????}

????public String getName() {
????????return name;
????}

????public void setName(String name) {
????????this.name = name;
????}

????public String getPassword() {
????????return password;
????}

????public void setPassword(String password) {
????????this.password = password;
????}

????public boolean isZaixian() {
????????return zaixian;
????}

????public void setZaixian(boolean zaixian) {
????????this.zaixian = zaixian;
????}
????public String toString(){
????????return "用户名"+name+"密码"+password+"是否在线"+zaixian;
????}
}
class UserTest{
????public static void main(String[] args) {
????????List list=new ArrayList();
????????list.add(new User("张三","123",true));
????????list.add(new User("李四","312",false));
????????list.add(new User("王五","456",true));
????????for(int i=0;i<list.size();i++){
????????????User u=(User)list.get(i);
????????????if (u.isZaixian()==true){
????????????????System.out.println(u);
????????????}

????????}
????}


}

11：（List）定义一个员工类(Employee):---要求封装

① 属性:姓名,生日月,工资

② 提供无参数\有参数的构造方法

③ 创建多个员工对象,存储在Employee数组中.

④ 利用toString方法展示所有员工的信息,要求格式为: 张三-10-18000.0

⑤ 控制台输入当前月份,统计过生日的员工数量.

⑥ 控制台输入一个工资,打印工资高于此工资的所有员工信息.

package com.by.homework3;

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

public class Employee {
????private String name;
????private int birthday;
????private double salary;

????public Employee() {
????}

????public Employee(String name, int birthday, double salary) {
????????this.name = name;
????????this.birthday = birthday;
????????this.salary = salary;
????}

????public String getName() {
????????return name;
????}

????public void setName(String name) {
????????this.name = name;
????}

????public int getBirthday() {
????????return birthday;
????}

????public void setBirthday(int birthday) {
????????this.birthday = birthday;
????}

????public double getSalary() {
????????return salary;
????}

????public void setSalary(double salary) {
????????this.salary = salary;
????}
????public String toString(){
????????return name+"-"+birthday+"-"+salary;
????}
}
class EmployeeTest{
????public static void main(String[] args) {
????????List list=new ArrayList();
????????list.add(new Employee("张三",10,10000));
????????list.add(new Employee("李四",9,20000));
????????list.add(new Employee("王五",8,30000));
????????list.add(new Employee("赵六",7,40000));
????????Scanner sc=new Scanner(System.in);
????????System.out.println("请输入当前月份");
????????int month=sc.nextInt();
????????for (int i=0;i<list.size();i++){
????????????Employee e=(Employee) list.get(i);
????????????if (e.getBirthday()==month){
????????????????System.out.println(e);
????????????}
????????}
????????System.out.println("请输入工资:");
????????double d=sc.nextInt();
????????for (int i=0;i<list.size();i++){
????????????Employee e=(Employee) list.get(i);
????????????if (e.getSalary()>d){
????????????????System.out.println(e);
????????????}
????????}


????}
}

12：（List）在控制台输入格式为“张三/18/男/99.5”的学生若干，存于List集合中。

要求：

①从数组遍历所有内容解析为学生对象，将学生在存于一个新的List集合

②遍历集合找出”优秀”的学生信息（优秀：成绩>=80）

③找出集合中没有参加考试的学生信息（成绩为null）

④排除集合中的重复元素

⑤制定成绩光荣榜（成绩从高到低打印学生成绩）