How to convert two dimensional array to one dimensional JAVA?

Question

Java

Faced with the stupidest problem in my endeavors. There is a two-dimensional array, namely a matrix of a fixed size 4 x 4. To implement one algorithm, it is more convenient for me to translate the matrix into a regular sequence of numbers written in a "line". Thank you very much in advance.

Answer 1

pseudocode

for (i=0; i<4; i++) {
  for(j=0; j<4; j++) {
    arr[i*4+j] = matr[i][j]
  }
}

Answer 2

Perhaps it would still be better?

int[] firstArray = { 1, 2 };
int[] secondArray = { 3, 4 };
int[] resultArray = new int[4];
    
System.arraycopy(firstArray, 0, resultArray, 0, 2);
System.arraycopy(secondArray, 0, resultArray, 2, 2);