java - 字符串输入未执行

Question

这个问题已经有答案了:

Scanner is skipping nextLine() after using next() or nextFoo()? (25 个回答)

已关闭 3 年前。

我开发了一个代码来获取学生分数的输入详细信息并将平均值打印为输出。此操作将一直执行，直到用户给出“n”作为循环条件的输入。但在我的代码中，用户无法给出条件输入，并且自动执行 while 循环

import java.util.Scanner;


class Student

 {

   String reg;

  int maths,phy,che,cse,avg;

void cal()

{

if(maths<50 | phy<50 | che<50 | cse<50)

{

System.out.println("The grade of the student will not be computed");

}

else

{

avg=((maths+phy+che+cse)/4);

if(avg>=91)

{

System.out.println("S");

}

if(avg>=81 && avg<=90)

{

System.out.println("A");

}



if(avg>=71  && avg<=80)

{

System.out.println("B");

}



if(avg>=61  && avg<=70)

{

System.out.println("C");

}


if(avg>=50 && avg<=60)

{

System.out.println("D");

}



}


}

}







 class Main1    //3rd

{

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

            Scanner w = new Scanner(System.in);
            String r = "Y", a = "Y";

            while (r.contains(a)) {

                Student s = new Student();
                System.out.println("Enter the marks for maths,physics,chemistry,CSE along with your Reg.no first");
                s.reg = w.nextLine();
                s.maths = w.nextInt();
                s.phy = w.nextInt();
                s.che = w.nextInt();
                s.cse = w.nextInt();
                System.out.println("press 'Y' to continue and 'N' to exit");
                a = w.nextLine();
                s.cal();

            }

        }

    }

实际输出:

C:\Program Files\Java\jdk-12.0.2\bin>java Main1

Enter the marks for maths,physics,chemistry,CSE along with your Reg.no first

100

100

100

100

100

press 'Y' to continue and 'N' to exit

S

Enter the marks for maths,physics,chemistry,CSE along with your Reg.no first

Answer 1

请在System.out.println("press 'Y' to continue and 'N' to exit");之前添加w.nextLine();，这样main 方法应该如下所示:

public static void main(String args[]) throws Exception {
    Scanner w = new Scanner(System.in);
    String r = "Y", a = "Y";

    while (r.contains(a)) {

        Student s = new Student();
        System.out.println("Enter the marks for maths,physics,chemistry,CSE along with your Reg.no first");
        s.reg = w.nextLine();
        s.maths = w.nextInt();
        s.phy = w.nextInt();
        s.che = w.nextInt();
        s.cse = w.nextInt();
        w.nextLine(); //------> Added
        System.out.println("press 'Y' to continue and 'N' to exit");
        a = w.nextLine();
        s.cal();