AsyncTask的和getInstalledPackages（）失败 [英] AsyncTask and getInstalledPackages() fail

问题描述

我真的不明白发生了什么，也许你可以给我一个想法。我为了让所有用户安装的应用程序及其权限的列表使用getInstalledPackages（）。下面是我如何做到这一点：

I don't really understand what is happening and maybe you can give me an idea. I use getInstalledPackages() in order to get a list of all user installed applications and their permissions. Here is how I do it:

private PackageManager pm;

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        pm = getPackageManager();
        getListData();
}

 private void getListData()
    {

        backTask = new BackTask();
        backTask.execute();
    }

 protected class BackTask extends AsyncTask<Context, String, ArrayList<App>>
    {
....
        @Override
        protected ArrayList<App> doInBackground(Context... param) 
        {

                try {

                      //get a list of installed apps.
                          List<PackageInfo> packages = pm.getInstalledPackages(PackageManager.GET_PERMISSIONS | PackageManager.GET_PROVIDERS);

                            for (PackageInfo packageInfo : packages) {
                                ApplicationInfo application = packageInfo.applicationInfo;
....
}

我需要刷新显示基于用户交互列表。问题出现在此行中的AsyncTask：

I need to refresh the list displayed based on user interaction. The problem appears at this line in AsyncTask:

List<PackageInfo> packages = pm.getInstalledPackages(PackageManager.GET_PERMISSIONS | PackageManager.GET_PROVIDERS);

有时候包包含了所有的安装的应用程序有时是空的。比方说，例如开出3次，第3次是空的。有鉴于此code OUT的AsyncTask，并把它放在getListData（）的作品没有任何问题，每一次。问题是，我得到一点点冻结，因为操作不上一回线。 那么什么是处理AsyncTask的？难道我做错了什么？

Sometimes packages contains all the installed apps sometimes is EMPTY. Let's say for example out of 3 times, the 3rd time is empty. Taking this code out of AsyncTask and put it on getListData() works every single time without any problems. The issue is that I get a little freeze because operation is not on a back thread. So what's the deal with AsyncTask ? Am I doing something wrong ?

推荐答案

签出相似，所以问题<一href="http://stackoverflow.com/questions/3455781/packagemanager-getinstalledpackages-returns-empty-list">here, CommonsWare认为，这种方法需要参与的UI线程，就我所看到的，这是唯一合理的解释。

Check out a similar SO question here, CommonsWare argues that this method need to be involved in UI thread, As far as I can see, this is the only reasonable explanation.

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