Android监听返回键、Home键+再按一次返回键退出应用

Android监听返回键需重写onKeyDown()方法

Home键keyCode==KeyEvent.KEYCODE_HOME

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
        //++自定义点击事件
        return true;//不执行父类的点击事件
    }
    return super.onKeyDown(keyCode, event);//继续执行父类的其他点击事件
}

实例：再按一次返回键退出应用

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(), "再按一次退出应用", Toast.LENGTH_SHORT).show();
            exitTime = System.currentTimeMillis();
        } else {
            finish();
            System.exit(0);
        }
        return true;
    }
    return super.onKeyDown(keyCode, event);
}