Android中的“再按一次返回键退出程序”de实现

private long exitTime = 0;

@Override

public boolean onKeyDown(int keyCode, KeyEvent event) {

if(keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN){

if((System.currentTimeMillis()-exitTime) > 2000){

Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show();

exitTime = System.currentTimeMillis();

} else {

finish();

System.exit(0);

}

return true;

}

return super.onKeyDown(keyCode, event);

}