基本完成，但是修改我不太理解所以没有写。

package 作业;

import java.util.Scanner; //控制输入
import java.awt.AWTException; //用来清空控制台的
import java.awt.Robot; //用来清空控制台的
import java.awt.event.InputEvent; //用来清空控制台的
import java.awt.event.KeyEvent; //用来清空控制台的

class Student {
    private String stunumber = "00000000";
    private String name = "***";
    private int age = 0;
    private boolean sex; // 男生为 false，女生为 true。
    private double score = 0;

    Student(String stunumber, String name, int age, boolean sex, double score) {
        this.stunumber = stunumber;
        this.name = name;
        this.age = age;
        this.sex = sex;
        this.score = score;
    }

    Student() {

    }

    public boolean isSex() {
        return sex;
    }

    public String getStunumber() {
        return stunumber;
    }

    public void setStunumber(String stunumber) {
        this.stunumber = stunumber;
    }

    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 void getSex() {
        if (this.sex == true)
            System.out.printf("女生");
        else
            System.out.printf("男生");
    }

    public void setSex(boolean sex) {
        this.sex = sex;
    }

    public double getScore() {
        return score;
    }

    public void setScore(double score) {
        this.score = score;
    }
}

public class 作业 {

    public static void main(String[] args) throws AWTException {

        Student[] stu = new Student[10];
        stu[0] = new Student("20170001", "王大", 18, true, 88);
        stu[1] = new Student("20170002", "李二", 17, false, 68);
        stu[2] = new Student("20170003", "张三", 16, true, 66);
        stu[3] = new Student("20170004", "李四", 16, false, 93);
        stu[4] = new Student("20170005", "王五", 17, true, 83);
        stu[5] = new Student();
        stu[6] = new Student();
        stu[7] = new Student();
        stu[8] = new Student();
        stu[9] = new Student();

        int key = 0;
        while (key != 6) {

            System.out.println("    1、 遍历输出学生信息；");
            System.out.println("    2、 新学生信息录入；");
            System.out.println("    3、 删除学生信息；");
            System.out.println("    4、 修改学生信息；");
            System.out.println("    5、 查询学生信息；");
            System.out.println("    6、 退出系统！；");
            System.out.print("请输入：");
            @SuppressWarnings("resource")
            Scanner scanner = new Scanner(System.in);
            key = scanner.nextInt();
            // boolean a = true ;

            switch (key) {
            case 1:
                clear();
                for (int i = 0; i < 10; i++) {
                    if (stu[i].getName() != "***")
                        ShowStudent(stu[i]);
                }
                System.out.println("输入任何数字返回主菜单");
                System.out.println("6.退出系统");
                System.out.print("请输入：");
                int m1;
                Scanner scanner10 = new Scanner(System.in);
                m1 = scanner10.nextInt();
                if (m1 != 6) {
                    clear();
                    key = 0;
                    break;
                } else if (m1 == 6) {
                    key = 6;
                    break;
                }
                break;
            case 2:
                clear();
                int j;
                for (j = 0; j < 10;) {
                    if (stu[j].getStunumber().equals("00000000"))
                        break;
                    else
                        j = j + 1;

                }

                // System.out.println(j);
                System.out.printf("请输入学号 ： ");
                Scanner scanner1 = new Scanner(System.in);
                String a = scanner1.next();
                stu[j].setStunumber(a);
                System.out.printf("请输入姓名 ： ");
                Scanner scanner2 = new Scanner(System.in);
                String b = scanner2.next();
                stu[j].setName(b);
                System.out.printf("请输入年龄 ： ");
                Scanner scanner3 = new Scanner(System.in);
                int c = scanner3.nextInt();
                stu[j].setAge(c);
                System.out.println("请输入性别  ： ");
                System.out.println("1.男生");
                System.out.println("2.女生");
                Scanner scanner4 = new Scanner(System.in);
                int d = scanner4.nextInt(); {
                boolean x;
                if (d == 2) {
                    x = true;
                    stu[j].setSex(x);
                } else if (d == 1) {
                    x = false;
                    stu[j].setSex(x);
                } else {
                    System.out.println("秀吉嘛？");
                }
            }
                System.out.printf("请输入成绩 ： ");
                Scanner scanner5 = new Scanner(System.in);
                double e = scanner5.nextDouble();
                stu[j].setScore(e);
                ShowStudent(stu[j]);
                System.out.println("输入任何数字返回主菜单");
                System.out.println("6.退出系统");
                System.out.print("请输入：");
                int m2;
                Scanner scanner11 = new Scanner(System.in);
                m2 = scanner11.nextInt();
                if (m2 != 6) {
                    clear();
                    key = 0;
                    break;
                } else if (m2 == 6) {
                    key = 6;
                    break;
                }
                break;

            case 3:
                clear();
                int y = 0;
                int z = 0;
                int k = 0;
                String f;
                System.out.printf("请输入学号：");
                Scanner scanner6 = new Scanner(System.in);
                f = scanner6.next();
                for (k = 0; k < 10; k++) {
                    if (deleteStudent(stu[k].getStunumber(), f)) {
                        z = z + 1;
                    }
                }

                // System.out.println(z);
                if (z != 0) {
                    y = 1;
                } else if (z == 0) {

                    System.out.println("不存在 这个数据。");
                }

                for (k = 0; k < 10; k++) {
                    if (deleteStudent(stu[k].getStunumber(), f)) {
                        stu[k].setName("***");
                        stu[k].setStunumber("00000000");
                        stu[k].setScore(0);
                        stu[k].setAge(0);
                        break;
                    }
                }

                for (k = 0; k < 10; k++) {
                    if (deleteStudent(stu[k].getStunumber(), f)) {
                        z = z + 1;
                    }
                }
                if (y == 1) {
                    System.out.println("删除成功！");
                }
                System.out.println("输入任何数字返回主菜单");
                System.out.println("6.退出系统");
                System.out.print("请输入：");
                int m3;
                Scanner scanner12 = new Scanner(System.in);
                m3 = scanner12.nextInt();
                if (m3 != 6) {
                    clear();
                    key = 0;
                    break;
                } else if (m3 == 6) {
                    key = 6;
                    break;
                }
                break;
            case 4:
               clear();
               
                    
                break;
            case 5:
                clear();
                System.out.println("查询方法：");
                System.out.println("1.学号    ");
                System.out.println("2.姓名    ");
                System.out.println("3.性别     ");
                System.out.println("4.年龄    ");
                System.out.printf("请输入：");
                int key1;
                int i;
                boolean j1 = true;
                Scanner scanner13 = new Scanner(System.in);
                key1 = scanner13.nextInt();
                switch (key1) {
                case 1:

                    System.out.printf("请输入学号：");
                    String stunumber1;
                    Scanner scanner21 = new Scanner(System.in);
                    stunumber1 = scanner21.next();
                    for (i = 0; i < 10; i++) {

                        if (stu[i].getStunumber().equals(stunumber1)) {
                            ShowStudent(stu[i]);
                            j1 = false;
                        }

                    }
                    if (j1)
                        System.out.println("没有此数据");
                    // System.out.println(j1);
                    break;
                case 2:
                    System.out.printf("请输入姓名：");
                    String name1;
                    Scanner scanner22 = new Scanner(System.in);
                    name1 = scanner22.next();
                    for (i = 0; i < 10; i++) {
                        if (stu[i].getName().equals(name1)) {
                            ShowStudent(stu[i]);
                            j1 = false;
                        }
                    }
                    if (j1)
                        System.out.println("没有此数据");
                    break;
                case 3:
                    int sex1;
                    System.out.println("1.女生        ");
                    System.out.println("2.男生        ");
                    System.out.printf("请输入性别：");
                    Scanner scanner25 = new Scanner(System.in);
                    sex1 = scanner25.nextInt();
                    if (sex1 == 1) {

                        for (i = 0; i < 10; i++) {
                            if (stu[i].isSex())
                                ShowStudent(stu[i]);
                        }
                    } else {
                        for (i = 0; i < 10; i++) {
                            if (stu[i].isSex()) {
                            } else {
                                if (stu[i].getName().equals("***")) {
                                } else {
                                    ShowStudent(stu[i]);
                                }
                            }
                        }
                    }

                    break;
                case 4:
                    System.out.printf("请输入年龄：");
                    int age1;
                    Scanner scanner24 = new Scanner(System.in);
                    age1 = scanner24.nextInt();
                    for (i = 0; i < 10; i++) {
                        if (stu[i].getAge() == age1) {
                            ShowStudent(stu[i]);
                            j1 = false;
                        }
                    }
                    if (j1)
                        System.out.println("没有此数据");
                    break;
                }
                System.out.println("输入任何数字返回主菜单");
                System.out.println("6.退出系统");
                System.out.print("请输入：");
                int m5;
                Scanner scanner15 = new Scanner(System.in);
                m5 = scanner15.nextInt();
                if (m5 != 6) {
                    clear();
                    key = 0;
                    break;
                } else if (m5 == 6) {
                    key = 6;
                    break;
                }
                break;
            }
        }

        System.out.println(stu[5].getStunumber());
        for (int i = 0; i <= 50; i++) {
            System.out.println();
        }

    }

    // 第一个方法
    public static void ShowStudent(Student stu1) {

        System.out.printf(" 学号 ：" + stu1.getStunumber() + "     ");
        System.out.println();
        System.out.printf(" 姓名 ：" + stu1.getName() + "     ");
        System.out.println();
        System.out.printf(" 年龄 ：" + stu1.getAge() + "     ");
        System.out.println();
        System.out.printf(" 性别 ：" + "     ");
        stu1.getSex();
        System.out.printf("     ");
        System.out.println();
        System.out.printf(" 成绩 ：" + stu1.getScore() + "     ");
        System.out.println();
        System.out.printf("____________________");
        System.out.println();
    }

    // 第二个方法
    // public static void addStudent ( String stunumber1, String name1, int age1,
    // boolean sex1, double score1)
    // {
    // Scanner scanner1 = new Scanner (System.in );
    // age1=scanner1.nextInt();
    // }
    // 第三个方法
    public static boolean deleteStudent(String stunumber3, String n) {

        if (stunumber3.equals(n)) {
            return true;
        } else {
            return false;
        }
    }

    public static void selectStudent() {

    }

    // 用来清空控制台的函数
    public static void clear() throws AWTException {
        Robot r = new Robot();
        r.mousePress(InputEvent.BUTTON3_MASK); // 按下鼠标右键
        r.mouseRelease(InputEvent.BUTTON3_MASK); // 释放鼠标右键
        r.keyPress(KeyEvent.VK_CONTROL); // 按下Ctrl键
        r.keyPress(KeyEvent.VK_R); // 按下R键
        r.keyRelease(KeyEvent.VK_R); // 释放R键
        r.keyRelease(KeyEvent.VK_CONTROL); // 释放Ctrl键
        r.delay(100);

    }

}

缺少注释这是我的一个缺点，以后会改正的。