Copy a 2D array with some of the values null

Question

I've added java.util.Arrays to deep print easily at the end (for this example), but I cant use it to copy the array

I need to copy this 2D array, but I just cant seem to figure out how to replace the inner array I create with just null. I have the main commented for what I need to do.

I create an array the size of the original array, but it places 3 null values in the inner loop because I initialize the array that way, but I dont know how else I could initialize the array, and have it be the same length.

import java.util.Arrays;

public class makeCopyOfArray {

  public static String[][] copyArray() {

    String[][] array = new String[][] {{"1", "1", "1"}, {"2", "2", "2"}, null, null, null};
    String[][] arrayCopy = new String[array.length][array[1].length];

    for (int i = 0; i < array.length; i++) {
      
      if (array[i] == null) {
        continue;
      }

      for (int j = 0; j < array[i].length; j++) {
        arrayCopy[i][j] = array[i][j];
      }
    }

    return arrayCopy;
  }

  public static void main(String[] args) {

    System.out.println(Arrays.deepToString(copyArray()));
    // prints out
    // [[1, 1, 1], [2, 2, 2], [null, null, null], [null, null, null], [null, null, null]]

    // need it to print out
    // [[1, 1, 1], [2, 2, 2], null, null, null]
  }
}

Answer 1

I figured it out. I just created a copy of the array that was filled with null.

import java.util.Arrays;

public class makeCopyOfArray {

  public static String[][] copyArray() {

    String[][] array = new String[][] {{"1", "1", "1"}, {"2", "2", "2"}, null, null, null};
    String[][] arrayCopy = new String[array.length][]; //create an array with just empty null

    //loop through array and copy to arrayCopy the inner lists that are not null.

    for (int i = 0; i < array.length; i++) {
      
      if (array[i] != null) {
        
        arrayCopy[i] = array[i];
      }
    }
    return arrayCopy;
  }

  public static void main(String[] args) {

    System.out.println(Arrays.deepToString(copyArray()));
  }
}