在不知道数组大小的情况下输入数组

有没有一种方法可以在Java中创建数组，而无需先定义或要求它的长度?也就是用户输入一些数字作为参数，然后程序会创建一个包含这么多参数的数组.

Is there a way to make an array in java, without defining or asking for it's length first ? A.k.a the user enters some numbers as arguments, and the program creates an array with that many arguments.

目前还不清楚您处于什么情况.如果您知道在执行时而不是在编译时的数组长度，那很好:

It's unclear exactly what situation you're in. If you know the array length at execution time but not at compile time, that's fine:

public class Test {
    public static void main(String[] args) {
        int length = Integer.parseInt(args[0]);
        String[] array = new String[length];
        System.out.println("Created an array of length: " + array.length);
    }
}

您可以将其运行为:

java Test 5

它将创建一个长度为5的数组.

and it will create an array of length 5.

如果您真的在创建数组之前不知道数组的长度，例如，是否要询问用户元素，然后让他们输入完成某些特殊值后，您可能希望使用某种List，例如ArrayList.

If you really don't know the length of the array before you need to create it - for example, if you're going to ask the user for elements, and then get them to enter some special value when they're done, then you would probably want to use a List of some kind, such as ArrayList.

例如:

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Test {
    public static void main(String[] args) throws Exception {
        Scanner scanner = new Scanner(System.in);

        System.out.println("Enter numbers, with 0 to end");
        List<Integer> list = new ArrayList<>();
        while (true) {
            int input = scanner.nextInt();
            if (input == 0) {
                break;
            }
            list.add(input);
        }
        System.out.println("You entered: " + list);
    }    
}

您可以然后根据实际需要将该List转换为数组，但理想情况下，您可以继续将其用作List.

You can then convert that List into an array if you really need to, but ideally you can just keep using it as a List.