package A;

import java.util.Stack;

public class Manage1 {
    Box head=new Box(0,"");

    public void add(Box box){//增
        Box temp=head;
        while (true){
            if (temp.next==null){
                break;
            }
            temp=temp.next;
        }
        temp.next=box;
        box.pre=temp;
    }

    public void printList(){//打印
        Box temp=head.next;
        if (temp==null){
            System.out.println("empty!");
            return;
        }
        while (true){
            if (temp==null){
                break;
            }
            System.out.println(temp);
            temp=temp.next;
        }
    }

    public void update(Box box){//改
        if (head.next==null){
            System.out.println("empty!");
            return;
        }
        Box temp=head.next;
        boolean flag=false;
        while (true){
            if (temp==null){
                break;
            }
            if (temp.id==box.id){
                flag=true;
                break;
            }
            temp=temp.next;
        }
        if (flag){
            temp.name=box.name;
        }else {
            System.out.println("没有找到");
        }
    }

    public void del(int id){//删
        if (head.name==null){
            System.out.println("empty!");
            return;
        }
        Box temp=head.next;
        boolean flag=false;
        while (true){
            if (temp==null){
                break;
            }
            if (temp.id==id){
                flag=true;
                break;
            }
            temp=temp.next;
        }
        if (flag){
            temp.pre.next=temp.next;
            if (temp.next!=null){
                temp.next.pre=temp.pre;
            }
        }else {
            System.out.println("no exist!");
        }

    }

}

package A;

public class Box {
    public int id;
    public String name;
    public Box next;
    public Box pre;

    public Box(int id, String name) {
        this.id = id;
        this.name = name;
    }

    @Override
    public String toString() {
        return "Box{" +
                "id=" + id +
                ", name=‘" + name + ‘\‘‘ +
                ‘}‘;
    }
}

package A;

public class List {
    public static void main(String[] args) {
        Manage1 manage1=new Manage1();
        Box one=new Box(1,"a");
        Box two=new Box(2,"ab");
        manage1.add(one);
        manage1.add(two);
        manage1.printList();
        System.out.println("=========修改");
        Box ome1=new Box(1,"a.a");
        manage1.update(ome1);
        manage1.printList();
        System.out.println("==========删除");
        manage1.del(2);
        manage1.printList();
    }
}

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