如何在执行功能期间使应用程序加载屏幕

    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowAnimationStyle">@null</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowIsFloating">true</item>
    <item name="android:backgroundDimEnabled">false</item>
</style>

    android:theme="@style/TransparentTheme">
</activity>

    android:id="@+id/progressBar"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:visibility="gone" />

ProgressBar progressBar = findViewById(R.id.progressBar);
// 显示加载屏幕
progressBar.setVisibility(View.VISIBLE);
// 隐藏加载屏幕
progressBar.setVisibility(View.GONE);

private class LoadDataTask extends AsyncTask<Void, Void, Void> {
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // 显示加载屏幕
        progressBar.setVisibility(View.VISIBLE);
    }

    @Override
    protected Void doInBackground(Void... params) {
        // 执行耗时操作
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        // 隐藏加载屏幕
        progressBar.setVisibility(View.GONE);
    }
}

new LoadDataTask().execute();