学生管理系统

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import javax.swing.JOptionPane;

public class HomeWork_13_Working {
    public static int numArray[] = new int[20];
    public static String nameArray[] = new String[20];
    public static int gradeArray[] = new int[20];
    public static int number = 0;

    public static void main(String[] args) {
        JOptionPane.showMessageDialog(null, "欢迎使用学生查询系统!");
        String user = "fj";
        String pwd = "1";
        boolean islogin = login(user, pwd);
        if (islogin == true) {
            for (;;) {
                String fuction = JOptionPane.showInputDialog(null, "1、添加" + "\n" + "2、显示" + "\n" + "3、删除" + "\n"
                        + "4、查找" + "\n" + "5、修改" + "\n" + "6、排序" + "\n" + "7、退出" + "\n");
                int t = Integer.parseInt(fuction);

                switch (t) {
                case 1:
                    add();
                    break;
                case 2:
                    show();

                    break;
                case 3:
                    del();
                    break;
                case 4:
                    find();
                    break;
                case 5:
                    amend();
                    break;
                case 6:
                    sort();
                    break;
                case 7:
                    System.exit(0);
                }
            }
        }
    }

    // 酷查下标
    public static int coolfind() {
        String name = JOptionPane.showInputDialog(null, "请输入姓名");
        int index = -1;
        for (int i = 0; i < nameArray.length; i++) {
            if (name.equals(nameArray[i])) {
                index = i;
                break;
            }
        }
        return index;

    }

    // 排序
    public static void sort() {
        for (int i = 0; i < gradeArray.length; i++) {
            for (int j = i + 1; j < gradeArray.length; j++) {

                if (gradeArray[i] < gradeArray[j]) {
                    int t = gradeArray[i];
                    gradeArray[i] = gradeArray[j];
                    gradeArray[j] = t;

                    String s = nameArray[i];
                    nameArray[i] = nameArray[j];
                    nameArray[j] = s;

                    int x = numArray[i];
                    numArray[i] = numArray[j];
                    numArray[j] = x;
                }
            }
        }
        show();
    }

    // 修改
    public static void amend() {
        int index = coolfind();
        if (index != -1) {
            String num = JOptionPane.showInputDialog(null, "请输入新学号");
            String name = JOptionPane.showInputDialog(null, "请输入新姓名");
            String grade = JOptionPane.showInputDialog(null, "请输入新成绩");

            numArray[index] = Integer.parseInt(num);
            nameArray[index] = name;
            gradeArray[index] = Integer.parseInt(grade);
            show();
        } else {
            JOptionPane.showMessageDialog(null, "查无此人");

        }
    }

    // 查找
    public static void find() {
        int index = coolfind();

        if (index == -1) {
            JOptionPane.showMessageDialog(null, "查无此人!");
        } else {
            JOptionPane.showMessageDialog(null,
                    "学号:" + numArray[index] + "  姓名:" + nameArray[index] + "  成绩:" + gradeArray[index]);
        }
    }

    // 删除
    public static void del() {
        int index = coolfind();
        if (index != -1) {
            for (int i = index; i < number; i++) {
                numArray[i] = numArray[i + 1];
                nameArray[i] = nameArray[i + 1];
                gradeArray[i] = gradeArray[i + 1];
            }
            number--;
            show();
        } else {
            JOptionPane.showMessageDialog(null, "查无此人");
        }

    }

    // 显示
    public static void show() {
        String str = "学号" + "  " + "姓名" + "  " + "分数" + "  " + "\n";
        for (int i = 0; i < number; i++) {
            str += numArray[i] + "        " + nameArray[i] + "    " + gradeArray[i] + "\n";
        }
        JOptionPane.showMessageDialog(null, str);

    }

    // 登录
    public static boolean login(String user, String pwd) {
        for (int i = 3; i > 0; i--) {
            String user1 = JOptionPane.showInputDialog(null, "请输入用户名");
            String pwd1 = JOptionPane.showInputDialog(null, "请输入密码");
            if (user1.equals(user) && pwd1.equals(pwd)) {
                JOptionPane.showMessageDialog(null, "登录成功!");
                return true;
            } else {
                if (i == 1) {
                    JOptionPane.showMessageDialog(null, "非法用户!");
                    System.exit(0);
                }
                JOptionPane.showMessageDialog(null, "用户名或密码错误");
            }
        }
        return false;
    }

    // 添加
    public static void add() {
        String numArray1 = JOptionPane.showInputDialog(null, "请输入学号");
        String nameArray1 = JOptionPane.showInputDialog(null, "请输入姓名");
        String gradeArray1 = JOptionPane.showInputDialog(null, "请输入成绩");
        numArray[number] = Integer.parseInt(numArray1);
        nameArray[number] = nameArray1;
        gradeArray[number] = Integer.parseInt(gradeArray1);
        number++;
    }
}




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