Change button background color as if pressed, but without the user pressing it

Issue

On Android, a Button changes its background color when pressed.

How can we tell a button that it is pressed (without firing the onClick-action), so that it changes color, without the user pressing it? (for example triggered by a swipe action)

It should change color briefly, and then change back.

There a quite a few questions concerning keeping the pressed state. This question asks, how to set the button_pressed state briefly, as if clicked, but without a real click.

Button.setPressed(true) has not given a color change, neither has Button.performClick().

Solution

To change a button state without anything else is done via

btn1.getBackground().setState(new int[]{android.R.attr.state_pressed});

To reset to ordinary, you use

btn1.getBackground().setState(new int[]{android.R.attr.state_enabled});

A Button's states can be found out via

btn1.getBackground().getState();

which resturns an int[]. You can compare its values to android.R.attr to find out which states are set.

Example Code

private void simulateClick(final ImageButton button,
                           final long clickDuration) {
    button.getBackground().setState(new int[]{android.R.attr.state_pressed});
    new Thread(new Runnable() {
        public void run() {
            try {
                Thread.sleep(clickDuration);
            } catch ( InterruptedException e ) {
                // not bad if interrupted: sleeps a bit faster (can happen?)
            }
            Count.this.runOnUiThread(new Runnable() {
                    public void run() {
                        button.getBackground().setState(new int[]{android.R.attr.state_enabled});
                    }
                });
        }}).start();
}

Explanation

Each View has a Drawable as background image. A Drawable can be of different subtypes, here it is a StateListDrawable, as defined per XML. (See @Lynx's answer as an example of a XML defined drawable).

This Drawable can be told which state it is to assume (via setState) and does the layout itself.

Answered By - serv-inc