学生信息管理系统Plus

StudentManagerPlus.java

package ly.com;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;

public class StudentManagerPlus {
    public static void main(String[] args) throws IOException {
        addMainPage("array.txt");
        return;
    }
    
    public static void addMainPage(String fileName) throws IOException {
        while (true) {
            System.out.println("------欢迎来到学生信息管理系统------");
            System.out.println("1.查看所有学生信息");
            System.out.println("2.添加学生");
            System.out.println("3.删除学生");
            System.out.println("4.修改学生");
            System.out.println("5.退出");
            
            System.out.println("请输入序号选择");
            Scanner sc = new Scanner(System.in);
            String inputStr = sc.nextLine();
            switch (inputStr) {
            case "1": // 1.查看所有学生信息
                getAllStudent(fileName);
                break;
            case "2": // 2.添加学生
                addStudent(fileName);
                break;
            case "3": // 3.删除学生
                removeStudent(fileName);
                break;
            case "4": // 4.修改学生信息
                modifyStudent(fileName);
                break;
            case "5": // 5.退出
            default:
                System.out.println("谢谢使用!");
                System.exit(0);
                break;
            }
        }
    }
    
    public static void readDataFromFile(ArrayList<Student> array, String fileName) throws IOException {
        BufferedReader br = new BufferedReader(new FileReader(fileName));
        String line;
        while (null != (line = br.readLine())) {
            String[] strArr = line.split("\t");
            Student stu = new Student(strArr[0], strArr[1], strArr[2], strArr[3]);
            array.add(stu);
//          System.out.println(line);
        }
        br.close();
        return;
    }
    
    public static void writeDataToFile(ArrayList<Student> array, String fileName) throws IOException {
        BufferedWriter bw = new BufferedWriter(new FileWriter(fileName));
        for (int i = 0; i < array.size(); i++) {
            Student stu = array.get(i);
            StringBuffer bs = new StringBuffer();
            bs.append(stu.getId()).append("\t");
            bs.append(stu.getName()).append("\t");
            bs.append(stu.getAge()).append("\t");
            bs.append(stu.getAddress()).append("\t");
            bw.write(bs.toString());
            bw.newLine();
            bw.flush();
        }
        bw.close();
        return;
    }
    
    public static void getAllStudent(String fileName) throws IOException {
        ArrayList<Student> array = new ArrayList<Student>();
        readDataFromFile(array, fileName);
        
        if (0 == array.size()) {
            System.out.println(fileName + "文件中没有学生信息");
            return;
        }
        
        System.out.println("学号\t姓名\t年龄\t住址");
        for (int i = 0; i < array.size(); i++) {
            Student stu = array.get(i);
            System.out.println(stu.getId() + "\t" + stu.getName() + "\t" + stu.getAge() + "\t" + stu.getAddress());
        }
        return;
    }
    
    public static void addStudent(String fileName) throws IOException {
        ArrayList<Student> array = new ArrayList<Student>();
        readDataFromFile(array, fileName);
        
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入需要添加的学生学号");
        String strId = sc.nextLine();
        
        if (0 != array.size()) {
            while (true) {
                int i = 0;
                for (; i < array.size(); i++) {
                    Student stu = array.get(i);
                    if (strId.equals(stu.getId())) {
                        System.out.println("该学号已被占用,请重新输入添加的学生学号");
                        strId = sc.nextLine();
                        break;
                    }
                }
                if (i == array.size()) {
                    break;
                }
            }
        }
        
        System.out.println("请输入学生姓名"); String strName = sc.nextLine();
        System.out.println("请输入学生年龄"); String strAge = sc.nextLine();
        System.out.println("请输入学生住址"); String strAddress = sc.nextLine();
        //sc.close();
        Student newStu = new Student(strId, strName, strAge, strAddress);
        array.add(newStu);
        
        writeDataToFile(array, fileName);
        System.out.println("添加学生成功");
        return;
    }
    
    public static void removeStudent(String fileName) throws IOException {
        ArrayList<Student> array = new ArrayList<Student>();
        readDataFromFile(array, fileName);
        
        if (0 == array.size()) {
            System.out.println("学生信息管理系统中没有学生信息,请重新输入");
            return;
        }
        
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入要删除的学生学号");
        String strId = sc.nextLine();
        
        int i = 0;
        while (true) {
            i = 0;
            for (; i < array.size(); i++) {
                if (true == strId.equals(array.get(i).getId())) {
                    break;
                }
            }
            if (i == array.size()) {
                System.out.println("未查找到该学生学号,请重新输入需要删除的学生学号");
                strId = sc.nextLine();
            } else {
                break;
            }
        }
        //sc.close();
        array.remove(i);
        
        writeDataToFile(array, fileName);
        System.out.println("删除学生成功");
        return;
    }
    
    public static void modifyStudent(String fileName) throws IOException {
        ArrayList<Student> array = new ArrayList<Student>();
        readDataFromFile(array, fileName);
        
        if (0 == array.size()) {
            System.out.println("学生信息系统中没有学生信息,请重新选择");
            return;
        }
        
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入需要修改的学生学号");
        String strId = sc.nextLine();
        int i = 0;
        while (true) {
            i = 0;
            for (; i < array.size(); i++) {
                if (true == strId.equals(array.get(i).getId())) {
                    break;
                }
            }
            if (i == array.size()) {
                System.out.println("未查找到该学生学号,请重新输入需要修改的学生学号");
                strId = sc.nextLine();
            } else {
                break;
            }
        }
        
        System.out.println("请输入新学生学号"); String newId = sc.nextLine();
        System.out.println("请输入新学生姓名"); String newName = sc.nextLine();
        System.out.println("请输入新学生年龄"); String newAge = sc.nextLine();
        System.out.println("请输入新学生住址"); String newAddress = sc.nextLine();
        //sc.close();
        Student stu = new Student(newId, newName, newAge, newAddress);
        array.set(i, stu);
        
        writeDataToFile(array, fileName);
        System.out.println("修改学生成功");
        return;
    }
    
}

小记:
昨晚为了消除Eclipse中的警告,添加了sc.close();,今晚运行的时候出问题了。实践证明,不能加这一句。

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