Why Am I Getting an InputMismatchException When Reading Double Values with Scanner?

Why Does the InputMismatchException Occur While Getting Double Values?

In Java, when using Scanner to read double values, an InputMismatchException can occur if the input does not strictly adhere to the expected decimal format.

Understanding the Issue:

The provided code contains the checkValueWithin and askForMarks methods. checkValueWithin is intended to validate numeric input within a specified range.

The issue arises in the askForMarks method, where user input is expected to be double values in the range of 0 to 30. However, the input might be formatted incorrectly, causing the Scanner to fail while parsing the double value.

Fix:

This issue can be resolved by ensuring that user input is formatted using a comma as the decimal separator instead of a dot. For example, instead of 1.2, enter 1,2. This aligns with the double value representation in Java.

Here's the modified code for askForMarks:

public void askForMarks() {
    double marks[] = new double[student];
    int index = 0;
    Scanner reader = new Scanner(System.in);
    while (index < student) {
        System.out.print("Please enter a mark (0..30): ");
        marks[index] = (double) checkValueWithin(0, 30);
        index++;
    }
}

This modification ensures that double values are entered correctly, preventing the Scanner from encountering an InputMismatchException.

The above is the detailed content of Why Am I Getting an InputMismatchException When Reading Double Values with Scanner?. For more information, please follow other related articles on the PHP Chinese website!