Java 数组使用用户输入和双打

Question

Our prompt for the problem is as follows:

This function will fill an array of doubles. It takes as its argument an array of doubles: the array that will hold the numeric information. It returns an integer that is equal to the number of values that were placed in the array. The function should start by declaring any variables that are needed. At a minimum, there should be two variables: an integer that will be used as a subscript and a double that will be used to hold a value that is entered by the user. Initialize the subscript variable to the beginning of the array. Prompt the user for a double number. This value should be saved in the double variable that was declared earlier. Inside of a loop that will execute as long as the the double number is not -99.99, the double number should be put into the array at the subscript position, the subscript should be incremented by 1, and the user should should be prompted for another double number. Once the loop is finished executing, the number of values that were placed in the array should be returned.

So far I have tried:

import java.util.*;

public class ArrayTest {

    public static void main(String[] args) {

        List<String> list = new ArrayList<>();

        Scanner input = new Scanner(System.in);

        int x = 0;

        do {
            System.out.println("Current list is " + list);

            System.out.println("Enter : ");
            list.add(input.next());

            if (input = -99.99)

        } while (x == 0);

        input.close();
        System.out.println("List is " + list);
        String[] arr = list.toArray(new String[0]);
        System.out.println("Array is " + Arrays.toString(arr));
    }
}

But am not able to compare the input to -99.99.

I would really appreciate if you guys took a look at my problem. Thanks!

Answer 1

You are comparing scanner ith -99.99

public static void main(String[] args) {

    List<String> list = new ArrayList<>();

    Scanner input = new Scanner(System.in);

    int x = 0;

    do {
        System.out.println("Current list is " + list);
        System.out.println("Enter : ");
        String next = input.next();
        list.add(next);

        if (Integer.parseInt(next) == -99.99) {
           // do logic
        }

    } while (x == 0);

    input.close();
    System.out.println("List is " + list);
    String[] arr = list.toArray(new String[0]);
    System.out.println("Array is " + Arrays.toString(arr));
  }
}