java - 一段时间后AsyncTask setMessage android java

Question

嗨，我的应用程序中有 AsyncTask，但我无法更改其 setMessage

例如:-

private class ProgressTask1 extends AsyncTask<String, Void, Boolean> {
    private ProgressDialog dialog;

        public ProgressTask1(MainActivity mainActivity) {
        context = mainActivity;
        dialog = new ProgressDialog(context);
    }

    private Context context;

    protected void onPreExecute() {

        this.dialog.setMessage("Checking system...");
        this.dialog.setCancelable(false);
        this.dialog.setTitle("Please Wait...");
        this.dialog.setIcon(R.drawable.ic_launcher);
        this.dialog.show();
    }

现在我想要更改 setmessage，我尝试将其添加到 doinbackground

    protected Boolean doInBackground(final String... args) {

    dothis1();
    this.dialog.setMessage("one done...");

dothis2();
this.dialog.setMessage("two done...");

但这使应用程序强制关闭，并且不要将其评价为低，因为我尽了最大努力并搜索了论坛，但能够解决此问题，因此在这个不错的社区请求帮助:)

有人可以帮忙吗？ :)

错误

05-13 23:36:34.899: E/AndroidRuntime(2454): Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.

Answer 1

ohmm，您不应该从后台线程更新 UI。要更新 UI，您可以通过两种方式进行:

1) 使用publishProgress (Progress...values) 和onProgressUpdate(...)。为此，您必须更改 AsynTask 类:

 private class ProgressTask1 extends AsyncTask<String, String, Boolean> {

    //.......... //your init
    @Override
    protected Boolean doInBackground(String... params) {
        //your background handle

        //publish to change UI
        String toShow = "your_string_here";
        publishProgress(toShow);
        //return ...; //your return value
    }

    @Override
    protected void onProgressUpdate(String... values) {
        super.onProgressUpdate(values);
        //detect message and show it.
        //this.dialog.setMessage(values[0]);
    }
}

2) 使用onPostExecute(....):

private class ProgressTask1 extends AsyncTask<String, Void, Boolean> {
    //.......... //your init

    @Override
    protected Boolean doInBackground(String... params) {
        //your background handle
        //return ...;//your return value
    }


    @Override
    protected void onPostExecute(Boolean aBoolean) {
        super.onPostExecute(aBoolean);
        String toShow = "your_string_here";
        //this.dialog.setMessage(toShow);
    }
}