Question

我有两个类，这个是XMLParser.java扩展活动并执行ClassAsynTask。现在我的ClassAsyncTask有问题，在onPostExecute部分你可以找到getApplicationContext（），我该如何解决这个错误？感谢

public class XMLParser extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    ClassAsyncTask aObj = new ClassAsyncTask(
            "http://www.androidpeople.com/wp-content/uploads/2010/06/example.xml");
    aObj.execute();

    /* layout to display the view */
    aObj.linearLayout = new LinearLayout(this);
    aObj.linearLayout.setOrientation(1);

    /* Set the ContentView to layout for display */
    this.setContentView(aObj.linearLayout);

}

}

这是ClassAsyncTask.java

public class ClassAsyncTask extends AsyncTask<String, Void, String> {


String targetURL;
TextView name[], website[], category[];
LinearLayout linearLayout;

public ClassAsyncTask(String site){
    targetURL = site;
}


@Override
protected String doInBackground(String... urls) {

    try {

        /* Handling XML */
        SAXParserFactory spf = SAXParserFactory.newInstance();
        SAXParser sp = spf.newSAXParser();
        XMLReader xr = sp.getXMLReader();

        /* Send URL to parse XML Tags */
        URL sourceUrl = new URL(targetURL);

        /* Create handler to handle XML Tags ( extends DefaultHandler ) */
        MyXMLHandler myXMLHandler = new MyXMLHandler();
        xr.setContentHandler(myXMLHandler);
        xr.parse(new InputSource(sourceUrl.openStream()));

    } catch (Exception e) {
        System.out.println("XML Pasing Excpetion = " + e);
    }
    return null;
}

/* Return-value from doInBackground */
protected void onPostExecute(String result) {

    /* Get result from MyXMLHandler SitlesList Object */
    SiteList sitesList = MyXMLHandler.sitesList;

    /* Assign TextView array length by arrayList size */
    name = new TextView[sitesList.getName().size()];
    website = new TextView[sitesList.getName().size()];
    category = new TextView[sitesList.getName().size()];

    int h = sitesList.getName().size();
    /* Set the result text in TextView and add it to layout */
    for (int i = 0; i < h; i++) {

        //This is where Im getting the error.
        name[i]= new TextView(getApplicationContext());
        name[i].setText("Name = " + sitesList.getName().get(i));

        website[i]= new TextView(getApplicationContext());
        website[i].setText("Website = " + sitesList.getWebsite().get(i));

        category[i]= new TextView(getApplicationContext());
        category[i].setText("Website Category = " + sitesList.getCategory().get(i));

        linearLayout.addView(name[i]);
        linearLayout.addView(website[i]);
        linearLayout.addView(category[i]);

    }
}

}

Answer 1

最简单的方法是将上下文传递给AsyncTask构造函数，然后在需要时使用它：

public class ClassAsyncTask extends AsyncTask {
    Context context;
    ...

    public ClassAsyncTask(String site, Context ctx){
        targetURL = site;
        context = ctx;
    }

    ...

}

将任务创建为：

ClassAsyncTask aObj = new ClassAsyncTask(
        "http://www.androidpeople.com/wp-content/uploads/2010/06/example.xml", this);

Answer 2

您可以创建构造函数，然后可以使用此上下文。私有上下文上下文;

ClassAsyncTask(Context context){
 this.context=context;

}

Answer 3

在你的onCreate方法中输入：

Context context = getApplicationContext();

在getApplicationContext()

中使用上下文变量代替onPostExecute

如何从中修复getApplication（）？

3 个答案: