How Do I Properly Initialize a Two-Dimensional Array in Java?

Multidimensional arrays allow the organization of data into multiple dimensions, a common example being a two-dimensional array often used to represent tables or matrices. Java provides syntax for the seamless creation of two-dimensional arrays, which this article delves into.

Consider the code snippet:

int[][] multD = new int[5][];
multD[0] = new int[10];

The intent may be to establish a two-dimensional array containing 5 rows and 10 columns, however, this approach encounters syntactic irregularities. To correctly instantiate a two-dimensional array with these dimensions, the following syntax should be employed:

int[][] multi = new int[5][10];

The provided construct serves as a concise representation that equates to the explicit definition:

int[][] multi = new int[5][];
multi[0] = new int[10];
multi[1] = new int[10];
multi[2] = new int[10];
multi[3] = new int[10];
multi[4] = new int[10];

It is imperative to remember that each element within the array is initialized to the default integer value, which is 0. This implies that the above definitions are equivalent to:

int[][] multi = new int[][] {
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
};

This can be further abbreviated to:

int[][] multi = {
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
};

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