public class MainActivity extends AppCompatActivity {  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    NineView view = new NineView(this);    setContentView(view);    view.setOnPasswordFinishListener(new NineView.OnPasswordFinishListener() {      @Override      public void onPasswordFinish(String password) {        Toast.makeText(getBaseContext(), "密碼:" + password, Toast.LENGTH_SHORT).show();      }    });  }}

public class NineView extends View {  int width;  Paint paintback = new Paint();  Paint paintsrc = new Paint();  int background;  //保證是正方形  int max = 6; //密碼的個數  6  int min = 4;  //點在哪里  float currX, currY;  public NineView(Context context) {    super(context);    init();  }  public NineView(Context context, AttributeSet attrs) {    super(context, attrs);    init();  }  public void init() {    paintback.setDither(true);    paintback.setAntiAlias(true);    paintsrc.setDither(true);    paintsrc.setAntiAlias(true);    //171625    background = Color.rgb(0x17, 0x16, 0x25);    paintback.setColor(background);    //3791E6    paintsrc.setColor(Color.rgb(0x37, 0x91, 0xe6));  }  @Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {    super.onMeasure(widthMeasureSpec, heightMeasureSpec);    width = getWidth() / 4;  }  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    //清屏    canvas.drawColor(background);    //劃線    if (result.size() > 0) {      //點      int x = result.get(result.size() - 1) % 3 + 1;      int y = result.get(result.size() - 1) / 3 + 1;      paintsrc.setStrokeWidth(10);      canvas.drawLine(x * width, y * width, currX, currY, paintsrc);      canvas.drawCircle(x * width, y * width, width / 3, paintback);      if (result.size() > 1) {        //防止越界        for (int i = 0; i < result.size() - 1; i++) { // 1 2 3 <=2          //需要取當前的i和下一個i          //按住的前一個點          int x1 = result.get(i) % 3 + 1;          int y1 = result.get(i) / 3 + 1;          //按住的后一個點          int x2 = result.get(i + 1) % 3 + 1;          int y2 = result.get(i + 1) / 3 + 1;          paintsrc.setStrokeWidth(10);          canvas.drawLine(x1 * width, y1 * width, x2 * width, y2 * width, paintsrc);          canvas.drawCircle(x1 * width, y1 * width, width / 3, paintback);        }      }    }    paintsrc.setStrokeWidth(2);    //9個圓    paintsrc.setStyle(Paint.Style.STROKE);    for (int i = 0; i < 3; i++) {      for (int j = 0; j < 3; j++) {        canvas.drawCircle((i + 1) * width, (j + 1) * width, width / 3, paintsrc);      }    }    paintsrc.setStyle(Paint.Style.FILL);    for (Integer integer : result) {      //i j ; // 8  2 2      int j = integer / 3 + 1;      int i = integer % 3 + 1;      canvas.drawCircle(i * width, j * width, width / 8, paintsrc);    }  }  //密碼  List<Integer> result = new ArrayList<>();  @Override  public boolean onTouchEvent(MotionEvent event) {    float x = event.getX();    float y = event.getY();    switch (event.getAction()) {      case MotionEvent.ACTION_DOWN:        //勾股定理        int i = isConnPoint(x, y);        //只要在園內        if (i != -1) {          result.add(i);          currX = x;          currY = y;        }        Log.e("TAG", "=====" + i);        break;      case MotionEvent.ACTION_MOVE:        currX = x;        currY = y;        //移動到其他的圓中，那么接著去添加result        int point = isConnPoint(x, y);        if (point != -1 && !result.contains((Integer) point)) {          result.add(point);          if (result.size() > max) {            //reslut清空            if (onPasswordFinishListener != null)              onPasswordFinishListener.onPasswordFinish(getPassword());            result.clear();          }        }        break;      case MotionEvent.ACTION_UP:        if (result.size() >= min) {          if (onPasswordFinishListener != null)            onPasswordFinishListener.onPasswordFinish(getPassword());        }        result.clear();        break;    }    invalidate();    return true;  }  public String getPassword() {    String password = "";    for (Integer integer : result) {      password += integer + "";    }    return password;  }  //判斷  public int isConnPoint(float x, float y) {    //9  width,width width    for (int i = 0; i < 3; i++) {      for (int j = 0; j < 3; j++) {        if (pointOnCircle(x, y, (j + 1) * width, (i + 1) * width)) {          return i * 3 + j; //0-8        }      }    }    return -1;  }  public boolean pointOnCircle(float x, float y, int cx, int cy) {//true    Log.e("TAG", ((cx - x) * (cx - x) + (cy - y) * (cy - y)) + "");    Log.e("TAG", ((float) width / 3f) * ((float) width / 3f) + "");    float i = ((cx - x) * (cx - x) + (cy - y) * (cy - y));    float j = ((float) width / 3f) * ((float) width / 3f);    return i < j;  }  public void setOnPasswordFinishListener(OnPasswordFinishListener onPasswordFinishListener) {    this.onPasswordFinishListener = onPasswordFinishListener;  }  private OnPasswordFinishListener onPasswordFinishListener;  public interface OnPasswordFinishListener {    void onPasswordFinish(String password);  }}