/**
 * @author 興趣使然黃小黃
 * @version 1.0
 * 學生類節(jié)點
 */
public class StudentNode {
    public String no; //學號
    public String name; //姓名
    public int age; //年齡
    public StudentNode pre; //指向前一個節(jié)點
    public StudentNode next; //指向下一個節(jié)點

    //構造器
    public StudentNode(String no, String name, int age ){
        this.no = no;
        this.name = name;
        this.age = age;
    }

    //為了顯示方便
    @Override
    public String toString() {
        return "StudentNode{" +
                "no='" + no + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

/**
 * @author 興趣使然黃小黃
 * @version 1.0
 * 學生雙向鏈表的具體實現(xiàn)
 */
public class StudentDoubleLinkedList {
    //定義頭節(jié)點
    private StudentNode head = new StudentNode("", "", 0);

    //獲取頭節(jié)點
    public StudentNode getHead(){
        return head;
    }

    //遍歷雙向鏈表的方法
    public void showList(){
        //判斷鏈表是否為空
        if (head.next == null){
            System.out.println("當前鏈表為空");
            return;
        }
        //遍歷 使用輔助指針
        StudentNode temp = head;
        while (temp != null){
            //更新指針
            temp = temp.next;
            if (temp.next == null){
                System.out.print(temp);
                break;
            }
            System.out.print(temp + "--->");
        }
    }

    //添加節(jié)點的方法
    //添加到尾部
    public void add(StudentNode newNode){
        //先找到最后一個節(jié)點
        StudentNode cur = head;
        while (true){
            //到達最后退出循環(huán)
            if (cur.next == null){
                break;
            }
            //更新指針
            cur = cur.next;
        }
        //添加操作
        newNode.next = cur.next; //也可以省略，因為恒為null
        cur.next = newNode;
        newNode.pre = cur;
    }

    //添加節(jié)點的方法
    //根據(jù)學號順序添加
    public void addByOrder(StudentNode newNode){
        //如果當前鏈表為空，則直接添加
        if (head.next == null){
            head.next = newNode;
            newNode.pre = head;
            return;
        }
        //按照學號找到對應位置
        StudentNode cur = head;
        boolean flag = false; //標識待添加的no是否存在
        while (true){
            if (cur.next == null){
                //已經(jīng)到達鏈表的尾部
                break;
            } else if (Integer.parseInt(cur.next.no) == Integer.parseInt(newNode.no)){
                //已經(jīng)存在
                flag = true;
                break;
            }else if (Integer.parseInt(cur.next.no) > Integer.parseInt(newNode.no)){
                //位置找到
                break;
            }
            cur = cur.next;
        }
        if (flag){
            System.out.println("當前no已經(jīng)存在，無法添加!");
        }else {
            //添加操作
            newNode.next = cur.next;
            cur.next = newNode;
            newNode.pre = cur;
        }
    }

    //根據(jù)no學號修改學生信息
    public void update(StudentNode studentNode){
        if (head.next == null){
            System.out.println("當前鏈表為空, 無法修改");
            return;
        }
        StudentNode temp = head.next;
        boolean flag = false; //表示是否找到節(jié)點
        while (true){
            if (temp == null){
                break;
            }
            if (temp.no == studentNode.no){
                flag = true;
                break;
            }
            temp = temp.next;
        }
        if (flag){
            temp.name = studentNode.name;
            temp.age = studentNode.age;
            System.out.println("更新成功!");
        }else {
            System.out.println("沒有找到");
        }
    }

    //從雙向鏈表中刪除節(jié)點
    public void delete(String no){
        //直接找到對應no的節(jié)點直接刪除
        StudentNode cur = head.next;
        boolean flag = false; //標記是否找到
        while (true){
            if (cur == null){
                break;
            }
            if (cur.no.equals(no)){
                flag = true; //找到了
                break;
            }
            cur = cur.next;
        }
        if (flag){
            //刪除操作
            //注意考慮最后一個節(jié)點后一個為空的情況
            if (cur.next != null) {
                cur.next.pre = cur.pre;
            }
            cur.pre.next = cur.next;
            System.out.println("刪除成功!");
        }else {
            System.out.println( no + "節(jié)點不存在，無法刪除！");
        }
    }
}

/**
 * @author 興趣使然黃小黃
 * @version 1.0
 * 雙向鏈表測試類
 */
public class DoubleLinkedListDemo {
    public static void main(String[] args) {
        StudentDoubleLinkedList doubleLinkedList = new StudentDoubleLinkedList();
        doubleLinkedList.addByOrder(new StudentNode("1", "黃小黃", 20));
        doubleLinkedList.addByOrder(new StudentNode("3", "懶羊羊", 20));
        doubleLinkedList.addByOrder(new StudentNode("2", "沸羊羊", 25));
        doubleLinkedList.addByOrder(new StudentNode("4", "美羊羊", 15));
        System.out.println("遍歷:");
        doubleLinkedList.showList();

        //測試更新方法
        System.out.println("\n更新編號為4的信息后:");
        doubleLinkedList.update(new StudentNode("4", "禰豆子", 14));
        doubleLinkedList.showList();

        //測試刪除方法
        System.out.println("\n刪除第一個和最后一個:");
        doubleLinkedList.delete("1");
        doubleLinkedList.delete("4");
        doubleLinkedList.showList();
    }
}