java - 如何设置一个改变ImageView图像资源的onTouchListener？

Question

我想设置一个 onTouchListener 来更改 ACTION_UP 和 ACTION_DOWN 上的 ImageViews 图像资源。这是我的代码:

    // Setup a basic upDownListener that registers UP and DOWN actions and changes the
    // view image resource accordingly
    View.OnTouchListener upDownListener = new View.OnTouchListener() {

        @Override
        public boolean onTouch(View v, MotionEvent event) {
            if(event.getAction() == MotionEvent.ACTION_DOWN) {
                // Button was pressed, change button background
                v.setImageResource(R.drawable.button_white_pressure);
                return true;
            } else if(event.getAction() == MotionEvent.ACTION_UP) {
                // Button was released, reset button background
                v.setImageResource(R.drawable.button_white);
                return true;
            }

            return false;
        }

    };

这段代码无法编译，因为View没有setImageResource方法，只有ImageView。但我如何告诉听众正在使用 ImageView？

Answer 1

将传入的 View 转换为 ImageView。

示例代码:

@Override
public boolean onTouch(View v, MotionEvent event) {
    ImageView iv = (ImageView) v;

    if (event.getAction() == MotionEvent.ACTION_DOWN) {
        iv.setImageResource(R.drawable.button_white_pressure);
        return true;
    } else if (event.getAction() == MotionEvent.ACTION_UP) {
        iv.setImageResource(R.drawable.button_white);
        return true;
    }

    return false;
}