Java - 每个输入记录多个用户输入

Question

该程序应该询问学生姓名。然后，对于每个学生，将记录四个成绩。然后再次迭代，直到用户输入“C”退出循环。然后打印结果。它仅显示最后输入的四个元素。我认为我的 for 循环不会实现我想要的。我可能需要 .forEach 吗？此后，我还必须分别对每个学生的每四个数字求和。每个学生必须有不同的 arrayList 吗？这是我到目前为止所拥有的：

package arrayList;

import java.util.Scanner;

import java.util.ArrayList;

public class TestGrades {

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

ArrayList<String> studentName = new ArrayList<String>(); 

boolean loop = true;

while (loop) {

  System.out.println(" Please Enter Student Name");

  sc.nextLine();

      String student = sc.nextLine();

        if(student.equals("C"))

        {

          break;    

        }

        else

        {

          studentName.add(student);

        }

        ArrayList<Double> studentGrade = new ArrayList<Double>();

    System.out.println("Please enter Student Grade");

    for (int j = 0; j < 4; j++) {

        Double grade = sc.nextDouble();

        studentGrade.add(grade);  

    }    

    System.out.println(studentName);

    System.out.print(studentGrade);

    }

}

}

我想按条目顺序打印每个 arrayList 的元素，首先是学生姓名，然后是学生成绩。.forEach 有帮助吗？

Answer 1

对于初学者，我建议使用该类获取用户输入Console。还：第一次调用时sc.nextLine()，您会从用户那里获取输入，但不会存储它。你应该初始化你的ArrayList<Double> studentGrade循环外。每次循环输入时，它都会创建一个新列表，并且您将丢失上一个循环的学生成绩。运行这个，如果你必须Scanner再次更改，请使用Scanner.import java.util.Scanner;import java.util.ArrayList;import java.io.Console;public class Test {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);ArrayList<String> studentName = new ArrayList<String>();&nbsp;ArrayList<Double> studentGrade = new ArrayList<Double>();boolean loop = true;while (loop) {&nbsp; &nbsp; System.out.println(" Please Enter Student Name");&nbsp; &nbsp; String student = scanner.nextLine();&nbsp; &nbsp; &nbsp; &nbsp; if(student.equals("C"))&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; else&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; studentName.add(student);&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; System.out.println("Please enter Student Grade");&nbsp; &nbsp; for (int j = 0; j < 4; j++) {&nbsp; &nbsp; &nbsp; &nbsp; Double grade = Double.parseDouble(scanner.nextLine());&nbsp; &nbsp; &nbsp; &nbsp; studentGrade.add(grade);&nbsp;&nbsp;&nbsp; &nbsp; }&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; System.out.println(studentName);&nbsp; &nbsp; System.out.print(studentGrade);&nbsp; }}}