Valid Sudoku

//Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.
//
//The Sudoku board could be partially filled, where empty cells are filled with the character '.'.
//
//
//A partially filled sudoku which is valid.
//
//Note:
//A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.
public class IsValidSudoku {


public static void main(String[] args) {
// TODO 自动生成的方法存根

}
public static boolean isValidSudoku(char[][] board) {
for( int i=0; i<9; i++){
        boolean[] usedLine = new boolean[9];
        for( int j=0; j<9; j++){
        if(board[i][j] != '.' && usedLine[ board[i][j]-'1' ] == false)
        usedLine[ board[i][j]-'1' ] = true; 
        else if( board[i][j] != '.' && usedLine[ board[i][j]-'1'] == true )
        return false;
        }
       }
       for( int i=0; i<9; i++){
        boolean[] usedRow = new boolean[9];
        for( int j=0; j<9; j++){
        if( board[j][i] != '.' && usedRow[ board[j][i] -'1'] == false)
        usedRow[ board[j][i] -'1'] = true;
        else if( board[j][i] != '.' && usedRow[ board[j][i]-'1' ] == true)
        return false;
        }
       }
       
       for( int lineStart =0; lineStart <9; lineStart += 3){
        for( int rowStart =0; rowStart <9; rowStart +=3){
        boolean[] usedSquare = new boolean[9];
        for( int i=lineStart; i<lineStart +3; i ++ ){
        for( int j= rowStart; j<rowStart +3; j ++){
        if( board[i][j] != '.' && usedSquare[ board[i][j] -'1'] == false)
        usedSquare[ board[i][j] -'1'] = true;
        else if(board[i][j] != '.' && usedSquare[ board[i][j] -'1'] == true )
        return false;
        }
        }
        }//lineStart
       }//rowStart
    return true;
    }


}