java - For循环前进两个数字而不是一个

Question

当我输入第一个输入时，它会同时打印第二个和第三个。控制台:

Please enter the grade for course 1
A
Please enter the grade for course 2
Please enter the grade for course 3

代码:

import java.io.IOException;
public class MyGradeLoops {
public static void main(String[] args) throws IOException{
int grade;
for (int i=1; i<6; i++) {
    System.out.println("Please enter the grade for course " + i);
    grade = System.in.read();
    }
    System.out.println("Thank your for submitting your grades");
   }
  }

Answer 1

System.in.read(); 将从用户输入中读取下一个字节。当您键入一个数字并按 Enter 时，它将至少计为三个字节(另外两个字节对应于 \r 和 \n 换行符)。

您可以简单地使用 Scanner 实例并使用 Scanner#nextInt() 读取整数。

Scanner in = new Scanner(System.in);
for (int i = 1; i < 6; i++) {
    System.out.println("Please enter the grade for course " + i);
    grade = in.nextInt();
}

如果 System.in.read() 是一项要求并且成绩作为字符串输入，这里有一种(有点古怪的)方法:

for (int i = 1; i < 6; i++) {
    String grade = "";
    System.out.println("Please enter the grade for course " + i);
    char c;
    while((c = (char) System.in.read()) != '\n') {
        grade += c;
    }
    System.out.println(grade);
}