小编Par*_*iya的帖子

我读了Hello Android书,我不明白这段功能的代码.

为什么我们在charAt(i)旁边使用-'0？

static protected int[] fromPuzzleString(String string) {
    int[] puz = new int[string.length()];
    for (int i = 0; i < puz.length; i++) {
        puz[i] = string.charAt(i) - '0' ;
    }
    return puz; 
 }

谢谢.干杯.

我读了Hello Android书,我不知道下面的代码.我不知道该怎么做getIntExtra()和putExtra()int这段代码.

 private void startGame(int i) {
     Log.d(TAG, "clicked on " + i);
     Intent intent = new Intent(Sudoku.this, Game.class);
     intent.putExtra(Game.KEY_DIFFICULTY, i);
     startActivity(intent);
 }

Game.java

public class Game extends Activity {
    private static final String TAG = "Sudoku" ;
    public static final String KEY_DIFFICULTY ="org.example.sudoku.difficulty" ;
    public static final int DIFFICULTY_EASY = 0;
    public static final int DIFFICULTY_MEDIUM = 1;
    public static final int DIFFICULTY_HARD = 2;
    private int puzzle[] = new int[9 * 9];
    private PuzzleView puzzleView;

    @Override
    protected void …