java扫描仪输入/输出格式错误

Question

此代码返回正确的最终结果，但控制台中输入和输出的格式不正确

以下是期望的结果：

Type your age: hello
Type your age: ?
Type your age: 3.14
Type your age: 25
Type your GPA: a
Type your GPA: bcd
Type your GPA: 2.5
age = 25, GPA = 2.5

该程序不断分别询问年龄和GPA，直到得到正确的输入，然后打印出来

以下是我得到的：

Type your age: hello
Type your age: ?
Type your age: 3.14
25
Type your GPA: a
Type your GPA: bcd
2.5
age = 25, GPA = 2.5

正如您所见，结果相同，但格式不正确。我确信这与我使用扫描器对象的方式有关，但我对扫描器的理解目前有限

下面是简单的代码：

Scanner console = new Scanner(System.in);
System.out.print("Type your age: ");
console.next();
while (!console.hasNextInt()) {
  System.out.print("Type your age: ");
  console.next();
}
int age = console.nextInt();

System.out.print("Type your GPA: ");
console.next();
while (!console.hasNextDouble()) {
  System.out.print("Type your GPA: ");
  console.next();
}
double gpa = console.nextDouble();
System.out.println("age = " + age + ", GPA = " + gpa);

Answer 1

完全删除while循环之前的console.next()，您不需要它。然后您将获得所需的输出。当您拥有console.next()时，您正在寻找并返回另一个完整的令牌，这在您的情况下并不需要

        Scanner console = new Scanner(System.in);
        System.out.print("Type your age: ");
        while (!console.hasNextInt()) {
            System.out.print("Type your age: ");
            console.next();
        }

        int age = console.nextInt();

        System.out.print("Type your GPA: ");

        while (!console.hasNextDouble()) {
            System.out.print("Type your GPA: ");
            console.next();
        }

        double gpa = console.nextDouble();
        System.out.println("age = " + age + ", GPA = " + gpa);