Java two-dimensional array

Two-dimensional array declaration and initialization of data
String [][]a={
    {"1", "2", "3"},
    {"4", "5", "6"}
    };

The form of a one-dimensional array:
(1),  int a[]; a = new int[5];  equivalent to int a[] = new INT[5];
(2),  int[] A; a = new int[5];  Equivalent to  int[] A = new int[5];

Two-dimensional arrays:
int a[][] = {{3,4,5,6}, {7,8,9}}; a two-dimensional array can be seen as an array of elements.
The Declaration and initialization of multidimensional arrays in Java should be in order from high to low dimensions, such as:
Method (1);
int a[][] = new int[3][];
A[0] = new INT[2];
A[1] = new INT[4];
A[2] = new int[3];//correct
int t[][] = new int[][4];//illegal
Method (2);
int a[][] = new int[3][5];//Correct, assign a two-dimensional array of three rows and five columns.

Java two-dimensional array