业务分析并搭建主菜单
需求:
采取控制台的方式去书写学生管理系统
分析:
初始菜单:

学生类:
属性:id 姓名 年龄 家庭住址
添加功能:
键盘录入每一个学生信息并添加,需要满足以下要求:
**-**id唯一
删除功能:
键盘录入要删除的学生的id,需要满足以下要求:
**-**id存在删除
**-**id不存在,需要提示不存在,并返回到初始菜单
修改功能:
键盘录入要修改的学生id,需要满足以下要求:
**-**id存在,继续录入其他信息
**-**id不存在,需要提示不存在,并回到初始菜单
查询功能:
打印所有的学生信息,需要满足以下要求:
**-**如果没有学生信息,提示:当前无学生信息,请添加后再查询
**-**如果有学生信息,需要按照以下格式输出.(不用过于纠结对齐的问题)

业务流程图:

主菜单:
(源代码)
java
package com.itheima.studentsystem;
import java.util.Scanner;
public class StudentSystem {
public static void main(String[] args){
loop:while (true) {
System.out.println("-----------------欢迎来到黑马学生管理系统---------------------");
System.out.println("1:添加学生");
System.out.println("2:删除学生");
System.out.println("3:修改学生");
System.out.println("4:查询学生");
System.out.println("5:退出");
System.out.println("请输入您的选择:");
Scanner sc = new Scanner(System.in);
String choose = sc.next();
switch (choose) {
case "1" -> System.out.println("添加学生");
case "2" -> System.out.println("删除学生");
case "3" -> System.out.println("修改学生");
case "4" -> System.out.println("查询学生");
case "5" -> {
System.out.println("退出");
//break loop;
System.exit(0);//停止虚拟机运行
}
default -> System.out.println("没有这个选项");
}
}
}
}
java
package com.itheima.studentsystem;
public class Student {
private String id;
private String name;
private int age;
private String address;
public Student() {
}
public Student(String id, String name, int age, String address) {
this.id = id;
this.name = name;
this.age = age;
this.address = address;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
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 String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
(运行结果截图)


补全功能:
(源代码)
java
package com.itheima.studentsystem;
import java.util.Scanner;
public class StudentSystem {
public static void main(String[] args){
loop:while (true) {
System.out.println("-----------------欢迎来到黑马学生管理系统---------------------");
System.out.println("1:添加学生");
System.out.println("2:删除学生");
System.out.println("3:修改学生");
System.out.println("4:查询学生");
System.out.println("5:退出");
System.out.println("请输入您的选择:");
Scanner sc = new Scanner(System.in);
String choose = sc.next();
switch (choose) {
case "1" -> addStudent();
case "2" -> deleteStudent();
case "3" -> updateStudent();
case "4" -> queryStudent();
case "5" -> {
System.out.println("退出");
//break loop;
System.exit(0);
}
default -> System.out.println("没有这个选项");
}
}
}
//添加学生
public static void addStudent(){
System.out.println("添加学生");
}
//删除学生
public static void deleteStudent(){
System.out.println("删除学生");
}
//修改学生
public static void updateStudent(){
System.out.println("修改学生");
}
//查询学生
public static void queryStudent(){
System.out.println("查询学生");
}
}
java
package com.itheima.studentsystem;
public class Student {
private String id;
private String name;
private int age;
private String address;
public Student() {
}
public Student(String id, String name, int age, String address) {
this.id = id;
this.name = name;
this.age = age;
this.address = address;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
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 String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
查询和添加
(源代码)
java
package com.itheima.studentsystem;
import java.util.ArrayList;
import java.util.Scanner;
public class StudentSystem {
public static void main(String[] args){
ArrayList<Student> list = new ArrayList<>();
loop:while (true) {
System.out.println("-----------------欢迎来到黑马学生管理系统---------------------");
System.out.println("1:添加学生");
System.out.println("2:删除学生");
System.out.println("3:修改学生");
System.out.println("4:查询学生");
System.out.println("5:退出");
System.out.println("请输入您的选择:");
Scanner sc = new Scanner(System.in);
String choose = sc.next();
switch (choose) {
case "1" -> addStudent(list);
case "2" -> deleteStudent(list);
case "3" -> updateStudent(list);
case "4" -> queryStudent(list);
case "5" -> {
System.out.println("退出");
//break loop;
System.exit(0);
}
default -> System.out.println("没有这个选项");
}
}
}
//添加学生
public static void addStudent(ArrayList<Student> list){
//利用空参构造先创建学生对象
Student s = new Student();
Scanner sc = new Scanner(System.in);
while (true) {
System.out.println("请输入学生id");
String id = sc.next();
boolean flag = contains(list, id);
if(flag){
//表示id已经存在,需要重新录入
System.out.println("id已经存在,请重新录入");
}else{
//表示id不存在,可以使用
s.setId(id);
break;
}
}
System.out.println("请输入学生姓名");
String name = sc.next();
s.setName(name);
System.out.println("请输入学生年龄");
String age = sc.next();
s.setName(age);
System.out.println("请输入学生家庭住址");
String address = sc.next();
s.setAddress(address);
//把学生对象添加到集合当中
list.add(s);
//提示一下用户
System.out.println("学生信息添加成功");
}
//删除学生
public static void deleteStudent(ArrayList<Student> list){
System.out.println("删除学生");
}
//修改学生
public static void updateStudent(ArrayList<Student> list){
System.out.println("修改学生");
}
//查询学生
public static void queryStudent(ArrayList<Student> list){
if(list.size() == 0){
System.out.println("当前无学生信息,请添加后再查询");
//结束方法
return;
}
//打印表头信息
System.out.println("id\t\tname\tage\taddress");
//当代码执行到这里,表示集合中是有数据的
for (int i = 0; i < list.size(); i++) {
Student stu = list.get(i);
System.out.println(stu.getId() + "\t" + stu.getName() + "\t" + stu.getAge() + "\t" + stu.getAddress() + "\t");
}
}
//判断id在集合中是否存在
public static boolean contains(ArrayList<Student> list, String id){
//循环遍历集合得到里面的每一个学生对象
for (int i = 0; i < list.size(); i++) {
//得到学生对象后,获取id并进行判断
Student stu = list.get(i);
String s = stu.getId();
if(s.equals(id)) {
//存在,true
return true;
}
}
//不存在,false
return false;
}
}
java
package com.itheima.studentsystem;
public class Student {
private String id;
private String name;
private int age;
private String address;
public Student() {
}
public Student(String id, String name, int age, String address) {
this.id = id;
this.name = name;
this.age = age;
this.address = address;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
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 String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
(运行结果截图)


删除和修改
(源代码)
java
package com.itheima.studentsystem;
import java.util.ArrayList;
import java.util.Scanner;
public class StudentSystem {
public static void main(String[] args){
ArrayList<Student> list = new ArrayList<>();
loop:while (true) {
System.out.println("-----------------欢迎来到黑马学生管理系统---------------------");
System.out.println("1:添加学生");
System.out.println("2:删除学生");
System.out.println("3:修改学生");
System.out.println("4:查询学生");
System.out.println("5:退出");
System.out.println("请输入您的选择:");
Scanner sc = new Scanner(System.in);
String choose = sc.next();
switch (choose) {
case "1" -> addStudent(list);
case "2" -> deleteStudent(list);
case "3" -> updateStudent(list);
case "4" -> queryStudent(list);
case "5" -> {
System.out.println("退出");
//break loop;
System.exit(0);
}
default -> System.out.println("没有这个选项");
}
}
}
//添加学生
public static void addStudent(ArrayList<Student> list){
//利用空参构造先创建学生对象
Student s = new Student();
Scanner sc = new Scanner(System.in);
while (true) {
System.out.println("请输入学生id");
String id = sc.next();
boolean flag = contains(list, id);
if(flag){
//表示id已经存在,需要重新录入
System.out.println("id已经存在,请重新录入");
}else{
//表示id不存在,可以使用
s.setId(id);
break;
}
}
System.out.println("请输入学生姓名");
String name = sc.next();
s.setName(name);
System.out.println("请输入学生年龄");
String age = sc.next();
s.setName(age);
System.out.println("请输入学生家庭住址");
String address = sc.next();
s.setAddress(address);
//把学生对象添加到集合当中
list.add(s);
//提示一下用户
System.out.println("学生信息添加成功");
}
//删除学生
public static void deleteStudent(ArrayList<Student> list){
Scanner sc = new Scanner(System.in);
System.out.println("请输入要删除的学生id");
String id = sc.next();
//查询id在集合中的索引
int index = getIndex(list,id);
//对index进行判断
//如果是-1就表示不存在,结束方法,回到初始菜单
if(index >= 0){
//如果大于等于0的,表示存在,直接删除
list.remove(index);
System.out.println("id为" + id + "的学生删除成功");
}else{
System.out.println("id不存在,删除失败");
}
}
//修改学生
public static void updateStudent(ArrayList<Student> list){
Scanner sc = new Scanner(System.in);
System.out.println("请输入要修改的学生id");
String id = sc.next();
int index = getIndex(list,id);
if(index == -1){
System.out.println("要修改的" + id + "不存在,请重新输入");
return;
}
//代码执行到这里,表示当前id是存在的
//获取要修改的学生对象
Student stu = list.get(index);
//输入其他信息并修改
System.out.println("请输入要修改的学生姓名");
String newName = sc.next();
stu.setName(newName);
System.out.println("请输入要修改的学生年龄");
int newAge = sc.nextInt();
stu.setAge(newAge);
System.out.println("请输入要修改的学生家庭住址");
String newAddress = sc.next();
stu.setAddress(newAddress);
System.out.println("学生信息修改成功");
}
//查询学生
public static void queryStudent(ArrayList<Student> list){
if(list.size() == 0){
System.out.println("当前无学生信息,请添加后再查询");
//结束方法
return;
}
//打印表头信息
System.out.println("id\t\tname\tage\taddress");
//当代码执行到这里,表示集合中是有数据的
for (int i = 0; i < list.size(); i++) {
Student stu = list.get(i);
System.out.println(stu.getId() + "\t" + stu.getName() + "\t" + stu.getAge() + "\t" + stu.getAddress() + "\t");
}
}
//判断id在集合中是否存在
public static boolean contains(ArrayList<Student> list, String id){
//循环遍历集合得到里面的每一个学生对象
/*for (int i = 0; i < list.size(); i++) {
//得到学生对象后,获取id并进行判断
Student stu = list.get(i);
String s = stu.getId();
if(s.equals(id)) {
//存在,true
return true;
}
}
//不存在,false
return false;*/
return getIndex(list,id) >= 0;
}
//通过id获取索引的方法
public static int getIndex(ArrayList<Student> list, String id){
//遍历集合
for (int i = 0; i < list.size(); i++) {
//得到每一个学生对象
Student stu = list.get(i);
//得到每一个学生对象的id
String s = stu.getId();
//拿着集合中的学生id跟要查询的id进行比较
if(s.equals(id)) {
//如果一样,那么就返回索引
return i;
}
}
//当循环结束之后还没有找到,就表示不存在,返回-1
return -1;
}
}
java
package com.itheima.studentsystem;
public class Student {
private String id;
private String name;
private int age;
private String address;
public Student() {
}
public Student(String id, String name, int age, String address) {
this.id = id;
this.name = name;
this.age = age;
this.address = address;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
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 String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}