Below is the syntax highlighted version of MagicSquare.java from §1.4 Arrays.

/******************************************************************************
 * Compilation: javac MagicSquare.java
 * Execution: java MagicSquare n
 *
 * Generates a magic square of order n. A magic squares is an n-by-n
 * matrix of the integers 1 to n^2, such that all row, column, and
 * diagonal sums are equal.
 *
 * One way to generate a magic square when n is odd is to assign
 * the integers 1 to n^2 in ascending order, starting at the
 * bottom, middle cell. Repeatedly assign the next integer to the
 * cell adjacent diagonally to the right and down. If this cell
 * has already been assigned another integer, instead use the
 * cell adjacently above. Use wrap-around to handle border cases.
 *
 *
 * % java MagicSquare 3
 * 4 9 2
 * 3 5 7
 * 8 1 6
 *
 * % java MagicSquare 5
 * 11 18 25 2 9
 * 10 12 19 21 3
 * 4 6 13 20 22
 * 23 5 7 14 16
 * 17 24 1 8 15
 *
 * Limitations
 * -----------
 * - n must be odd
 *
 ******************************************************************************/
publicclassMagicSquare{
publicstaticvoidmain(String[] args){
int n = Integer.parseInt(args[0]);
if(n %2==0)thrownewRuntimeException("n must be odd");
int[][] magic =newint[n][n];
int row = n-1;
int col = n/2;
 magic[row][col]=1;
for(int i =2; i <= n*n; i++){
if(magic[(row +1)% n][(col +1)% n]==0){
 row =(row +1)% n;
 col =(col +1)% n;
}
else{
 row =(row -1+ n)% n;
// don't change col
}
 magic[row][col]= i;
}
// print results
for(int i =0; i < n; i++){
for(int j =0; j < n; j++){
if(magic[i][j]<10) System.out.print(" ");// for alignment
if(magic[i][j]<100) System.out.print(" ");// for alignment
 System.out.print(magic[i][j]+" ");
}
 System.out.println();
}
}
}