Question

我的程序在doInBackground之后崩溃，并且没有来到onPostExecute。

我的活动代码的相关部分是这样的：

public static class News {
    private String title;
    private String content;
    private Bitmap image;

    public News(String nTitle, String nContent, Bitmap nImage){
        title = nTitle;
        content = nContent;
        image = nImage;
    }
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_news);
    final AsyncTask task = new DatabaseConnection(this, Method.GET_ALL_NEWS).execute();
    try {
        task.wait();
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}


public final void fillListView(List<News> news){
    recentNews = news;
    if(recentNews != null && !recentNews.isEmpty()){
        ((ListView)findViewById(R.id.lvNews)).setOnItemClickListener(this);
        final int size = recentNews.size();
        final String newsTitles[] = new String[size];
        for(int i=0; i<size; ++i)
            newsTitles[i] = recentNews.get(i).title;

        ((ListView)findViewById(R.id.lvNews)).setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, newsTitles));
    }
}

@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
    final News selectedNews = recentNews.get(position);
    startActivity(new Intent(this, ANewsActivity.class)
        .putExtra("title", selectedNews.title)
        .putExtra("content", selectedNews.content)
        .putExtra("image", BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher)));

}

我的AsyncTask代码的相关部分是这样的：

public DatabaseConnection(Context nContext, Method nMethod){
    method = nMethod;
    context = nContext;
}

@Override
protected void onPreExecute() {
    progressDialog = new ProgressDialog(context);
    progressDialog.setMessage(context.getString(R.string.database_connection_wait_message));
    progressDialog.setTitle(R.string.database_connection_wait_title);
    progressDialog.show();
}

@SuppressWarnings("incomplete-switch")
@Override
protected Void doInBackground(String... params) {
    if(method != Method.NONE){
        open();
        try{
            switch(method){
            case GET_ALL_NEWS:
                final ResultSet rs = conn.createStatement().executeQuery("select baslik, metin, resim from haberler");
                news =  new ArrayList<News>();
                while(rs.next())
                    news.add(new News(rs.getString(1), rs.getString(2), BitmapFactory.decodeStream(rs.getBlob(3).getBinaryStream())));
                break;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            close();
        }
    }
    return null;
}

@SuppressWarnings("incomplete-switch")
@Override
protected void onPostExecute(Void temp) {
    if (progressDialog.isShowing()){
        progressDialog.dismiss();
        switch(method){
        case GET_ALL_NEWS:
            ((NewsActivity)context).fillListView(news);
            break;
        }
        method = Method.NONE;
    }
}

我希望UI线程等到数据库操作完成。顺便说一下，变量等没有初始化问题，数据库返回正确的信息，我的“新闻”变量正常填充。

顺便说一句，我意识到它正在EMULATOR上的PHONE，STUCKS上工作很有趣（如果我在主线程代码上删除了wait（）方法及其try-catch块）。

Answer 1

如果没有logcat输出，很难说崩溃是什么，但由于你在.wait()中调用了onCreate()方法，它很可能是应用程序的主线程。您的onCreate()已迫不及待 - 它必须初始化并退出，否则您将阻止应用的主线程并取消AsyncTask的目的。

Android程序在doInBackground停止，并且没有来到onPostExecute

1 个答案: