Game of Life

public class SpielDesLebens {
	public static void main(String[] args){
		int msize = field();
		int[][]setrix;		
		int[][] matrix = new int [msize][msize];
		for(int i = 0; i < msize; i++ ){
			System.out.print("Eingabe der " + (i+1) + ".Zeile: ");
			String s = In.readString();
			for(int j = 0; j < msize; j++ ){
				matrix[i][j] = Integer.parseInt(s.substring(j , j+1));
			}
		}
		setrix = compare(matrix);
		output(matrix);
		output(setrix);
	}		
	public static int[][] compare(int[][] matrix){
		int z;
		int[][] setrix = new int [matrix.length][matrix.length];
		for(int y = 0; y < matrix.length; y++){
			for(int x = 0; x < matrix.length; x++){
				z = 0;
				for(int shifty = -1; shifty <= 1; shifty++){		
					for(int shiftx = -1; shiftx <= 1; shiftx++){
						int nachbarx = x+shiftx;
						int nachbary = y+shifty;				
						if (nachbarx < 0) nachbarx = (nachbarx + matrix.length);
						if (nachbary < 0) nachbary = (nachbary + matrix.length);
						if (nachbarx >= matrix.length) nachbarx = (nachbarx - matrix.length);
						if (nachbary >= matrix.length) nachbary = (nachbary - matrix.length);
						if (nachbarx == x && nachbary == y) continue;						
						if (matrix[nachbary][nachbarx] > 0)	z++;
					}
				}
				setrix [y][x] = 0;
				if (matrix [y][x] == 1 && (z == 2 || z == 3)) setrix [y][x] = 1;
				if (matrix [y][x] == 0 && z == 3) setrix [y][x] = 1;	
			}	
		}
		return setrix;
	}	
	public static void output(int[][] matrix){
		for(int i = 0; i < matrix.length; i++){
			for(int j = 0; j < matrix.length; j++){
				System.out.print(matrix[i][j]);
			}
		System.out.println();
		}
	System.out.println("~~~~~~~");
	}
	public static int field(){
		int z;
		System.out.println("Bitte geben Sie die Dimension der Matrix an (n*n): ");
		z = In.readInt();		
		System.out.println("Die Matrix hat die Groesse " + z + "*" + z + " Felder.");
		return z;
	}
}