Question

我试着让我的代码像这样： https://github.com/jbeerdev/BrightHubCode/blob/master/src/com/bright/hub/background/WebServiceBackgroundActivity.java 这就是我用Async类调用和发送的方式，这看起来很好。如果我将所有代码放在我的MainActivity中它只是起作用，但我似乎无法通过外部类来获取此代码。

我的主要活动代码:(重要的部分）

public class MainActivity extends FragmentActivity implements ActionBar.OnNavigationListener {

private static final String url = "http://www.somesite.com/JSON.php";
public String post;
public ListView listView;
public String jsonResult;

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initializeDialog();
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.listView1);
accessWebService();
}
private void accessWebService() {
    JsonReadTask jsonTask = new JsonReadTask();
    jsonTask.execute(new String[] { url, post },this);
}

private void initializeDialog() {
    dialog = ProgressDialog.show(MainActivity.this, "", "LoadingData. Wait...", true);
    dialog.show();
    }   

    public void ListDrawer() {
    List<Map<String, String>> galleryList = new ArrayList<Map<String, String>>();

    try {

   JSONObject jsonResponse = new JSONObject(jsonResult);
   JSONArray jsonMainNode = jsonResponse.optJSONArray("galleries");

   for (int i = 0; i < jsonMainNode.length(); i++) {
    JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);

    String loc = jsonChildNode.optString("loc");
    String foto = jsonChildNode.optString("foto");
    String outPut = "http://www.somesite.com/images/" + loc + foto;
    galleryList.add(createGallery("galleries", outPut));
   }
  } catch (JSONException e) {
  //Toast.makeText(getApplicationContext(), "Error" + e.toString(),
     //Toast.LENGTH_LONG).show();
  }

}

但是在Async类上： https://github.com/jbeerdev/BrightHubCode/blob/master/src/com/bright/hub/background/WebServiceAsyncTask.java ^我得到这些错误：“java.lang.String []无法强制转换为java.lang.String” 所以这发生了：“String serviceUrl =（String）params [0];”是我有问题的地方..？它至少在“doInBackground”中：“执行doInBackground（）时出错”

我的异步类代码:(重要的部分）

    public class JsonReadTask extends AsyncTask<Object, Void, String> {
    MainActivity callerActivity;
    @Override
    public String doInBackground(Object... params) {

    callerActivity = (MainActivity) params[1];
    HttpClient httpclient = new DefaultHttpClient();
    String theurl = (String) params[0]; //urlJSON

    HttpPost httppost = new HttpPost(theurl);
    try {
    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
    String thepost = (String) params[1]; //tablename
    nameValuePairs.add(new BasicNameValuePair("getgallery", "thepost"));
    httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
    HttpResponse response = httpclient.execute(httppost);


        callerActivity.jsonResult = inputStreamToString(response.getEntity().getContent()).toString();
    }

    catch (ClientProtocolException e) {
    e.printStackTrace();
    } catch (IOException e) {
    e.printStackTrace();
    }
    return null;
    }

应用程序在启动时崩溃，导致Dialog崩溃。在此先感谢您的帮助！

编辑我的logcat：http://pastebin.com/XZaNZTTg

Answer 1

崩溃日志中有两条重要的行：

10-13 11:49:43.881: E/AndroidRuntime(7289): Caused by: java.lang.ClassCastException: java.lang.String[] cannot be cast to java.lang.String
10-13 11:49:43.881: E/AndroidRuntime(7289):     at com.example.providenceartapp.JsonReadTask.doInBackground(JsonReadTask.java:31)

在某处您尝试将字符串数组用作单个字符串，它看起来就好像在这里

String theurl = (String) params[0]; //urlJSON;

params[0]是一个数组。

将json异步代码放入单独的类... Android

1 个答案: