在 Android 中为视图创建点击处理程序

Question

我正在编写一个非常简单的 Android 应用程序，它在主视图上显示各种形状：

public class Figures extends Activity {
    DemoView demoview;
    int figure_type = 1;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        demoview = new DemoView(this);
        setContentView(demoview);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.firstmenu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch(item.getItemId()) {
        case R.id.color_menu_item:
            break;
        case R.id.circle_menu_item:
            figure_type = 0;
            break;
        case R.id.square_menu_item:
            figure_type = 1;
            break;
        case R.id.triangle_menu_item:
            figure_type = 2;
            break;
        case R.id.exit_menu_item:
            super.finish();
            break;
        default:
            break;
        }
        return true;
    }

    private class DemoView extends View {
        public DemoView(Context context) {
            super(context);
        }

        @Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);

            Display display = getWindowManager().getDefaultDisplay();
            int width = display.getWidth();
            int height = display.getHeight();

            Paint paint = new Paint();
            paint.setStyle(Paint.Style.FILL);                
            paint.setColor(Color.WHITE);
            canvas.drawPaint(paint);

            if (figure_type == 0)
            {                
                // circle
                Random randomColor = new Random();
                paint.setColor(randomColor.nextInt());
                canvas.drawCircle(width/2, height/2-100, 100, paint);
            }
            else if (figure_type == 1)
            {                
                // square
                Random randomColor = new Random();
                paint.setColor(randomColor.nextInt());
                canvas.drawRect(80, 80, 220, 220, paint);
            }
            else if (figure_type == 2)
            {
                // triangle
                Random randomColor = new Random();
                paint.setColor(randomColor.nextInt());

                Path path = new Path();
                path.moveTo(width/2, 30);
                path.lineTo(width/2+100, height/2-50);
                path.lineTo(70, 190);
                path.close();
                canvas.drawPath(path, paint);
            }
        }
    }
}

如何执行点击屏幕（或DemoView）的事件？

Answer 1

您需要在视图上设置onClickListener。即在 onCreate 中：

demo.setOnClickListener( new View.onClickListener() {
  public void  onClick  (View v) {
    // do click behavior here.
  });