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java基础之集合框架 ArrayList和LinkedList的使用

时间:2024-09-15 13:50:54浏览次数:10  
标签:java String author ArrayList list name price public LinkedList

 ArrayList和LinkedList的使用

Link是接口,ArrayList和LinkedList是去实现这个接口,List接口没有LinkedList类的方法,如果需要LinkedList的方法就不能写成List list = new LinkedList(),只能LinkedList list = new LinkedList()

1.ArrayList的使用

        1.1.ArrayList采用长度可变数组,分配连续空间,效率很高

        1.2.ArrayList操作数据

        代码如下:

package began;

import java.util.ArrayList;

public class list {
    public static void main(String[] args) {
        //定义集合对象
        ArrayList list = new ArrayList();
        //添加元素
        list.add(1);    //add(object boj)
        list.add("你好");
        //插入元素
        list.add(1,1.5);    add(int index,object obj)
        //删除元素 remove(Object)
        list.remove(0);    remove(object obj)和remove(index)
        //遍历打印集合
        for (int i=0;i<list.size();i++){
            System.out.println(list.get(i)); //get:下标访问数组
        }
    }
}


//判断是否存在指定元素:contains()

        1.3实际应用场景:图书管理系统

        1.3.1.主函数

package began;

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

public class BOOKbody {
    public static void main(String[] args) {
        //定义一个集合list保存多本书
        ArrayList list = new ArrayList();

        BOOK b1=new BOOK("小王子",30,"圣埃克苏佩里");
        BOOK b2=new BOOK("阿泰勒的角落",50,"李娟");
        //加入书籍
        list.add(b1);
        list.add(b2);

        //插入书籍
        BOOK b3=new BOOK("平凡的世界",90,"路遥");
        list.add(1,b3);

        //删除元素
        list.remove(b1);
        list.remove(0);

        //查询元素
        if(list.contains(b2)){
            System.out.println("存在该图书");
        }else{
            System.out.println("不存在该书");
        }

        for (int i=0;i<list.size();i++){
            System.out.println(list.get(i));
            //两种打印方法皆可
            BOOK b=(BOOK)list.get(i);//将list.get(i)强制转为BOOK类型
            System.out.println(b); //get:下标访问数组
        }
    }
}

        1.3.1副函数 

package began;

public class BOOK {
    //类的属性
    private String name;
    private int price;
    private String author;

    //===============构造==============
    public BOOK(String name, int price, String author) {
        this.name = name;
        this.price = price;
        this.author = author;
    }

    //========重写toString() show=======
    @Override
    public String toString() {
        return "BOOK{" +
                "name='" + name + '\'' +
                ", price=" + price +
                ", author='" + author + '\'' +
                '}';
    }

    //===============封装=================
    public String getName() {
        return name;
    }

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

    public int getPrice() {
        return price;
    }

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

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }
}

2.LinkedList的使用

        2.1.主函数

        list.getLast();//返回列表最后一个元素

        list.First();//返回列表第一个元素

        图书管理系统示例代码:

package began;

import java.util.LinkedList;

public class BOOKbodylinkedlist {
    public static void main(String[] args) {
        //LinkedList:链表-->数据区+指针区
        LinkedList list = new LinkedList(); //List接口没有LinkedList类的方法,不能写成List list = new LinkedList()

        BOOKlinkedlist b1=new BOOKlinkedlist("小王子",30,"圣埃克苏佩里");
        list.add(b1);
        BOOKlinkedlist b2=new BOOKlinkedlist("阿泰勒的角落",50,"李娟");
        BOOKlinkedlist b3=new BOOKlinkedlist("平凡的世界",90,"路遥");
        list.addFirst(b2);
        list.addLast(b3);

        //获取第一本书
        BOOKlinkedlist first =(BOOKlinkedlist) list.getFirst();
        System.out.println(first);
        System.out.println("==============");
        //获取最后一本书
        BOOKlinkedlist last =(BOOKlinkedlist) list.getLast();//返回列表最后一个元素
        System.out.println(last);
        System.out.println("==============");

        //删除
        list.removeFirst();
        list.removeLast();

        //输出
        for (int i=0;i<list.size();i++){
            BOOKlinkedlist b=(BOOKlinkedlist)list.get(i);
            System.out.println(b);
        }
    }
}

        2.2.副函数(与上边一样)

package began;

public class BOOKlinkedlist {
    //类的属性
    private String name;
    private int price;
    private String author;

    //===============构造==============
    public BOOKlinkedlist(String name, int price, String author) {
        this.name = name;
        this.price = price;
        this.author = author;
    }

    //========重写toString() show=======
    @Override
    public String toString() {
        return "BOOK{" +
                "name='" + name + '\'' +
                ", price=" + price +
                ", author='" + author + '\'' +
                '}';
    }

    //===============封装=================
    public String getName() {
        return name;
    }

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

    public int getPrice() {
        return price;
    }

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

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }
}

标签:java,String,author,ArrayList,list,name,price,public,LinkedList
From: https://blog.csdn.net/2303_80933038/article/details/142282323

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