Java数组输入方法无响应问题排查及移除数组中7的功能实现求助

Why Your Input Method Isn't Responding #

The problem with your userInput() method is that Scanner.hasNextInt() is a blocking call — it will keep waiting indefinitely for more integer input until you signal the end of input. On most systems, you can do this by pressing:

• Ctrl + D (Linux/macOS)
• Ctrl + Z (Windows, then press Enter)

Without this signal, the program sits there waiting for you to keep entering numbers, making it look unresponsive. Let's tweak the method to add a user-friendly prompt so you know how to finish inputting.

Improved Input Method #

Here's an updated version with clear instructions for the user:

import java.util.Arrays;
import java.util.Scanner;

public class RemoveSevens {
    static Scanner in = new Scanner(System.in);

    public static int[] userInput() {
        int[] inputs = new int[5];
        int currentSize = 0;
        
        System.out.println("Enter integers (type a non-integer or press Ctrl+D/Ctrl+Z to finish):");
        while (in.hasNextInt()) {
            // Resize array if we're running out of space
            if (currentSize == inputs.length) {
                inputs = Arrays.copyOf(inputs, 2 * inputs.length);
            }
            inputs[currentSize] = in.nextInt();
            currentSize++;
        }
        // Trim the array to the actual number of elements entered
        inputs = Arrays.copyOf(inputs, currentSize);
        return inputs;
    }

Implementing the Remove-7 Logic #

Now let's add the function that removes all 7s, shifts remaining elements left, and fills empty spots with 0s:

public static int[] removeSevens(int[] arr) {
        int nonSevenCount = 0;
        // First count how many elements aren't 7
        for (int num : arr) {
            if (num != 7) {
                nonSevenCount++;
            }
        }

        // Create a result array (original array length is preserved)
        int[] result = new int[arr.length];
        int index = 0;
        // Copy non-7 elements to the front
        for (int num : arr) {
            if (num != 7) {
                result[index++] = num;
            }
        }
        // Remaining positions are already 0 by default in Java, no extra work needed
        return result;
    }

Putting It All Together with a Main Method #

Add a main method to test everything end-to-end:

public static void main(String[] args) {
        int[] inputArray = userInput();
        int[] processedArray = removeSevens(inputArray);
        
        System.out.println("Original array:");
        printArray(inputArray);
        
        System.out.println("\nArray with all 7s removed and gaps filled with 0:");
        printArray(processedArray);
    }

    // Helper method to print arrays neatly
    public static void printArray(int[] arr) {
        System.out.print("[");
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i]);
            if (i != arr.length - 1) {
                System.out.print(", ");
            }
        }
        System.out.println("]");
    }
}

How to Test It #

1. Run the program — it will prompt you to enter integers.
2. Type in numbers like 7 2 7 5 3 and then press Ctrl+D/Ctrl+Z to end input.
3. You'll see the original array and the processed array with 7s removed, and the end filled with 0s.

For example, if you input 7 2 7 5 3, the processed array will be [2, 5, 3, 0, 0].

内容的提问来源于stack exchange，提问作者Antonia Farina