点两下退出

@Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (event.getAction() == KeyEvent.ACTION_DOWN && keyCode == KeyEvent.KEYCODE_BACK) {
            exit();
            return false;
        }
        return super.onKeyDown(keyCode, event);
    }

    private void exit() {
        if ((System.currentTimeMillis() - exitTime ) > 2000) {
            showToast( "再按一次退出程序");
            exitTime = System.currentTimeMillis();
        } else {
            finish();
            android.os.Process.killProcess(android.os.Process.myPid());
            System.exit(0);
        }
    }

开发者涨薪指南

48位大咖的思考法则、工作方式、逻辑体系