Two Java-based mobile phone "Sudoku" games

The rules of Sudoku are very simple, and it is a little similar to the "nine palace grid" in our country. In the "chessboard" composed of nine nine-grid squares, there are already some numbers. Players need to fill in a number from 1 to 9 in the remaining blank grids so that each number appears only once in each row, each column, and each nine-grid square of the "chessboard" to pass the level.