How to clear 2d array in java and how to take backup my 2d array?

Question

I want to take backup of my 2d array and is there any way how to do this? and how to remove all elements of array ?

int arryNumbers[][]= new int[4][5];

http://stackoverflow.com/questions/1686425/copy-a-2d-array-in-java — 001, Apr 19 '16 at 12:57

Ahmad · Accepted Answer · 2016-04-19T14:08:42.363

1

you can clear array by Loop over the array and and set each element to null.

For String Case:

for( int i = 0; i < arryNumbers.length; i++ )
   Arrays.fill( arryNumbers[i], null );

For int Case:

for (int row = 0; row < ROW.length; row++) {
   for (int col = 0; col < COL.length; col++) {
      arry[row][col] = 0;
   }
}

you take backup by taking (Deep Copy) of your array.

Deep Copy Code:

public int[][] copy(int[][] input) {
      int[][] target = new int[input.length][];
      for (int i=0; i <input.length; i++) {
        target[i] = Arrays.copyOf(input[i], input[i].length);
      }
      return target;
}

edited Apr 19 '16 at 14:08

answered Apr 19 '16 at 13:00

Ahmad

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You cannot use `null` in the fill method of an int[] array: `Arrays.fill(int[],int)` – Ioannis Deligiannis Apr 19 '16 at 13:28

score 1 · Answer 2 · answered Apr 19 '16 at 13:01

1

Take a backup : arrayNumbers.clone();

To remove all elements, I guess you should do it yourself with "for" loops statements. (Or set it to null and instantiate it again)

answered Apr 19 '16 at 13:01

MedAl

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score 0 · Answer 3 · answered Apr 19 '16 at 13:25

Probably not what you are looking for but does what you ask in probably the fastest way:

int[][] newArray = oldArray;
oldArray=new int[4][5];

This is the fastest way to achieve what you describe. Note that initializing a new array sets the values to '0' in the case of int or 'null' inthe case of objects.

PS. if old oldArray is not symmetric then you can just iterate and initialize each "row" independently.

How to clear 2d array in java and how to take backup my 2d array?

3 Answers3