java - 如何重新排列数组以使空值占据数组的开头？

Question

我不知道如何将空元素添加到数组的前面。

有什么办法可以在不反转数组的情况下做到这一点吗？或许有具体的方法？

public static void main(String[] args) {
    String[] stringArray = new String[]{"one", "two", "three"};
    method(stringArray);
}

public static String[] method(String[] stringArray) {
    String[] biggerStringArray = Arrays.copyOf(stringArray, stringArray.length * 2);

    for (int i = 0; i < biggerStringArray.length; i++) {
        System.out.print(biggerStringArray[i] + ", ");

    }

    return biggerStringArray;
}

我希望结果看起来像:

null, null, null, one, two, three,

而不是:

one, two, three, null, null, null

Answer 1

public static void main(String[] args) {
    String[] stringArray = new String[] {"one", "two", "three"};
    method(stringArray);
  }

  public static String[] method(String[] stringArray) {
    String[] biggerStringArray = new String[stringArray.length * 2];

    for (int i = 0; i < stringArray.length; i++) {
      biggerStringArray[i + biggerStringArray.length / 2] = stringArray[i];
    }

    for (int i = 0; i < biggerStringArray.length; i++) {
      System.out.print(biggerStringArray[i] + ", ");
    }
    return biggerStringArray;
  }

编辑:刚刚记得您还可以使用 System.arraycopy :

public static String[] method(String[] stringArray) {
    String[] biggerStringArray = new String[stringArray.length * 2];

    System.arraycopy(stringArray, 0, biggerStringArray, biggerStringArray.length / 2, stringArray.length);

    for (int i = 0; i < biggerStringArray.length; i++) {
      System.out.print(biggerStringArray[i] + ", ");
    }
    return biggerStringArray;
  }