static String[][][] School= new String[1000][20][5];
Consider figure which has 3 Dimension.
So when you insert School[0][0][0]="A1"
it means you have entered element at 0,0,0 position.
From 0,0,0 this will move upto the position 1000,20,5.
You can insert like this But you have so many elements.
School[0][0][0]="A1"
School[0][0][1]="A2"
School[0][0][2]="A3"
.....
School[0][1][0]="B1"
School[0][1][1]="B2"
School[0][1][2]="B3"
......
In 3D array elements look like
int[3][4][2] array3D
// means Three (4x2) 2 Dimensional Arrays
int[4][2]
//means Four 1 dimensional arrays.
Now how to add elements in 3D array?
At Start you can directly use
int[][][] threeDArray =
{ { {1, 2, 3}, { 4, 5, 6}, { 7, 8, 9} },
{ {10, 11, 12}, {13, 14, 15}, {16, 17, 18} },
{ {19, 20, 21}, {22, 23, 24}, {25, 26, 27} } };
This is very tedious task in your case as you want to insert details at every position.
As you have 1000
records.
Your array will have elements like this
NOTE:It's not recommended to use 3D array for this purpose.
Suggestion:Declare a class with three Strings
create constructor with this three parameters and put getter and setters to get and set values via Objects