Android点击两次返回键，退出应用程序

Android点击两次返回键，退出应用程序

 

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(this, "在点击一次返回键将退出", 1000).show();
                exitTime = System.currentTimeMillis();
            } else {
                finish();
                System.exit(0);
            }
            return true;
        }

        return super.onKeyDown(keyCode, event);
    }