Sudoku Generator.

[Sth]

I'm trying to make a valid 9 X 9 sudoku set. I tried it by making blocks of 3X3 and checking for the rules of sudoku on the way as i made other blocks. The code works for like 4 blocks(sometimes 1) and then it freezes. Need help.

import java.util.Random;
   
public class wtf {

	/**
	 * @param args
	 */
	
	public static void main(String[] args) {
		
		int[] check;
		
		check = new int[9];
		
		int [][] sudoku;
		
		sudoku= new int[10][10];
		
		int i, j, k=0, z, t=0;
		boolean c=true;
		
		Random no = new Random(); 
		
		for (int cellc=0; cellc<3; cellc++){
			for (int cellh=0; cellh<3; cellh++){

		
				clear(check, 9);
				t=0;
				
				for (i=3*cellc; i<=(3*cellc+2); i++){
					for (j=3*cellh; j<=(3*cellh+2); j++){
						
						for(c=true; c==true;){
						
							z = no.nextInt(9)+1;
							
							c=linearSearch(check, 9, z);
							
							if ((c==true) || (vertical(sudoku, z, j)==true) || (horizontal(sudoku, z, i)==true))
							{ 
								c=true;
								continue;
							}
							
							
							check[t]=z;
							t++;
							sudoku[i][j]=z;
							
						}
						
					}
				}
				psudo(sudoku);
		
			}
		}
		
		
		
		
		
		

		
		
		// TODO Auto-generated method stub

	}



public static boolean linearSearch(int[] a, int upto, int key) {
    
    for (int i = 0; i < upto; i++) {
        if (key == a[i]) {
            return true;  // Found key, return index.
        }
    }
    return false;        // Failed to find key
}

public static void clear(int [] a, int upto)
{
	for (int i = 0; i < upto; i++)
	{
		a[i]=0;
	}
}

public static boolean vertical(int[][] sudoku, int a, int column)
{
	for (int i = 0; i < 9; i++) {
        if (a == sudoku[i][column]) {
            return true; 
        }
    }
    return false;    
	
	
	
}

public static boolean horizontal(int [][]sudoku, int a, int row)
{
	for (int i = 0; i < 9; i++) {
        if (a == sudoku[row][i]) {
            return true; 
        }
    }
    return false;    
}


public static void psudo(int[][] sudoku)
{int i,j;
	for (i=0; i<=8; i++){
		for (j=0; j<=8; j++){
			System.out.print(sudoku[i][j]+ "  ") ;
			
		}
		System.out.println();
		
	}
	
}




}