Reshape the Matrix

/* Programmer     : Dhruv Patel
*  Problem Name   : Reshape the Matrix
*  Used In        : Leetcode
*  Used As        : Challange
*  Problem        => 
*  In MATLAB, there is a very useful function called 'reshape', which can reshape a matrix into a new one with a different size but keep its original data.
*  You're given a matrix represented by a two-dimensional array, and two positive integers r and c representing the row number and column number of the wanted reshaped matrix, respectively.
*  The reshaped matrix need to be filled with all the elements of the original matrix in the same row-traversing order as they were.
*  If the 'reshape' operation with given parameters is possible and legal, output the new reshaped matrix; Otherwise, output the original matrix.
*  Example 1:
*     Input: 
*       nums = [[1,2],[3,4]] r = 1, c = 4
*     Output: 
*       [[1,2,3,4]]
*  Explanation:
*  The row-traversing of nums is [1,2,3,4]. The new reshaped matrix is a 1 * 4 matrix, fill it row by row by using the previous list.
*  Example 2:
*     Input: 
*      nums = [[1,2],[3,4]] r = 2, c = 4
*     Output: 
*      [[1,2],[3,4]]
*  Explanation:
*  There is no way to reshape a 2 * 2 matrix to a 2 * 4 matrix. So output the original matrix.
*  Note:
*     The height and width of the given matrix is in range [1, 100].
*     The given r and c are all positive.
*/

import java.util.*;
class Reshape_The_Matrix {
      public int[][] matrixReshape(int[][] nums, int r, int c) {
        int len = nums.length;
        int ans[][] = new int[r][c];
        List<Integer> l1 = new ArrayList<>();        
                for(int i=0;i<len;i++) {
                    for(int j=0;j<nums[i].length;j++) {
                        l1.add(nums[i][j]);
                    }
                }
                    int index=0;
                    for(int m=0;m<r;m++){
                      for(int k=0;k<c;k++){
                          if(l1.size()>0){
                          ans[m][k]=l1.remove(index);
                              }else{
                                    if(((r-m)>1 | (c-k)>1)){
                                      return nums;
                                   }
                                      break;
                              }
                     }
                }
                    return ans;
        }
          public static void main(String args[]) {
            int nums[][] = {{1,2},{3,4}};
              int r = 1;
              int c = 4;
                System.out.println(matrixReshape(nums,r,c));
        }
}