讀取文字檔案中Student.txt中內容（編號，姓名，成績）存放到學生物件中，並新增到集合，然後將分數低於等於80分的學生輸出到另外一個檔案中

大概說一下，這裡面加上main函式一共有addlist()、outgrade()、creatstu()4個方法。

其中addlist為讀取檔案內容，然後賦值給學生物件並將學生物件新增到集合。

outgrade 方法為將成績低於等於80分的學生輸出到另外一個檔案裡。

creatstu為建立一個學生物件

讀寫檔案中的路徑我也沒有刪除，如果誰需要的話定義兩個檔案路徑就可以了。

附上兩個檔案的圖片，介紹寫的有點亂，誰需要的話就得稍微費點點時間了，大家共同學習，共同進步。加油加油加油！

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package Demo2;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class Listdemo {

public static void main(String[] args) throws IOException {
    addlist();
    outgrade();
}

public static List<Student> list = new ArrayList<Student>();

public static void addlist() {

    File file = new File("C:\\Users\\Administrator\\Desktop\\abcde - 副本.txt");
    try {
        BufferedReader br = new BufferedReader(new FileReader(file));
        String str = null;
        while ((str = br.readLine()) != null) {
            String[] arr = str.split(",");
            Student stu = null;
            for (int i = 0; i < arr.length; i++) {
                stu = creatstu();
                stu.setStuID(Integer.parseInt(arr[0]));
                stu.setName(arr[1]);
                stu.setAge(Integer.parseInt(arr[2]));
                stu.setGrade(Integer.parseInt(arr[3]));
            }
            list.add(stu);
        }
    } catch (NumberFormatException e) {
        e.printStackTrace();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    for (Student student : list) {
        System.out.println(student);
    }
}

public static Student creatstu() {
    Student stu = new Student();
    return stu;
}

public static void outgrade() throws IOException {
    File file1 = new File("C:\\Users\\Administrator\\Desktop\\123.txt");
    BufferedWriter br1 = null;
    br1 = new BufferedWriter(new FileWriter(file1));
    for (Student student : list) {
        if (student.getGrade() <= 80) {
            br1.write(student.getStuID() + "," + student.getName() + "," + student.getAge() + ","
                    + student.getGrade());
            br1.flush();
            br1.newLine();
        }
        System.out.println(student);
    }
    br1.close();

}
 

}