-2

几天来，我一直在严重地解决这个问题。当我调用一个名为 populatespinner() 的函数时出现问题。rowNO、nodeAll 和 msg 是全局声明的字符串。任何帮助将不胜感激，在此先感谢。D

在 populatespinner() 中：-

 public void populateSpinner()
    {
        String nodestring="";
     //   ArrayList<String> itemsNode = new ArrayList<String>();

        try
        {
            if(count!=1)
            {
                StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();

                StrictMode.setThreadPolicy(policy); 


                                try {

                           try{
                                    new DownloadWebPageTask().execute("http://www.scom.co.in/Group1ReturnData2.Aspx?row=1");

                                        //if(rowNo.equalsIgnoreCase(""))
                                            rowNo=msg;
                                //      rowNo=OpenHttpConnection1("http://www.scom.co.in/Group1ReturnData2.Aspx?row=1");
                                        if(rowNo.equals("4"))
                                        {

                                    new DownloadWebPageTask().execute("http://www.scom.co.in/Group1ReturnData2.Aspx?row=2");
                                    nodeAll=msg;
                                        }

                                                } catch (Exception e) {
                                    // TODO Auto-generated catch block
                                    e.printStackTrace();
                                }
                                }
                         catch (Exception e) {
                            e.printStackTrace();
                        }

    } 
        if(rowNo.equals("4"))     
        for(int i=1;i<=4;i++)
        {

                String[] nodeIdName=nodeAll.split(",");                               
             String nodeVal=nodeIdName[i-1];
             String[] nodeparts=nodeVal.split(" ");

            if(i==1)
            {
            nodestring +=nodeparts[1];//nodeVal.substring(1,1);
            }
            else
            {
            {
                nodestring ="";//" \" ";
                nodestring +=nodeparts[1];

        }

             items1[i-1] = nodestring;
        }   
        count +=1;

}

        catch(Exception e)
        {
            textView.setText(e.toString());
            textView = (TextView) findViewById(R.id.txtCon);

        }


    }

现在在 DownloadWebPageTask() 类中：-

   private class DownloadWebPageTask extends AsyncTask<String, Void, String> {
            @Override
            protected String doInBackground(String... urls) {
              String response = "";
              for (String url : urls) {
                DefaultHttpClient client = new DefaultHttpClient();
                HttpGet httpGet = new HttpGet(url);
                try {


                  String s = "";
                  s=OpenHttpConnection1(url);
                 // while ((s = buffer.readLine()) != null) {
                    response += s;
                  //}

              //   response="http request failed " + execute.getStatusLine();
                } catch (Exception e) {
                    response= e.toString();
                    e.printStackTrace();
                }
              }
            //  msg=response;
              return response;

            }
            @Override
            protected void onPostExecute(String result) {
                msg=result;
            //   textView.setText(result);
         //     textView.setVisibility(View.INVISIBLE);

            }
          }

并来自 OpenHttpConnection1(url) 方法：-

 private String OpenHttpConnection1(String urlString)
        throws IOException
        {
        String responseStr="";
        InputStream in = null;
        int response = -1;
        URL url = new URL(urlString);
        URLConnection conn = url.openConnection();
        if (!(conn instanceof HttpURLConnection))
        throw new IOException("Not an HTTP connection");
        try{
        HttpURLConnection httpConn = (HttpURLConnection) conn;
        httpConn.setAllowUserInteraction(false);
        httpConn.setInstanceFollowRedirects(true);
        httpConn.setRequestMethod("GET");
        httpConn.connect();
        response = httpConn.getResponseCode();

        if (response==200)//(response == HttpURLConnection.HTTP_OK) {
        {
        in = httpConn.getInputStream();
        BufferedReader buffer = new BufferedReader(new InputStreamReader(in));

        String s = "";
        while ((s = buffer.readLine()) != null)
        {
            responseStr += s;
         }
      }
        else
        responseStr="http request failed " +'"'+  httpConn.getResponseMessage() +'"' + " ( " + response +" )";
        in.close();
        httpConn.disconnect();
        } 
        catch (Exception e) {
            responseStr=  e.toString();//.printStackTrace();
       }

        msg=responseStr;
        return responseStr;


}

以及在 Main 中产生错误的地方：-

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_tabular);


   //    Button btwn = (Button)findViewById(R.id.btnRec);
    //   btwn.setBackgroundColor(Color.YELLOW);


        this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

      //-------Spinner(DropDown)----------

        populateSpinner();

     //*/
        //====================

     //   String[] items1 = new String[]{"Node-1", "Node-2", "Node-3","Node-4"};

      // itemsNode.add(nodestring);

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item,items1);

        Spinner dropdown = (Spinner)findViewById(R.id.spinner2);
        dropdown.setAdapter(adapter);  


      // final String ttt;
        Spinner spinner = (Spinner)findViewById(R.id.spinner2);
        spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
            private boolean checked;
            @Override
            public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
                // your code here
                try{
                Spinner mySpinner = (Spinner)findViewById(R.id.spinner2);
                  Text = mySpinner.getSelectedItem().toString();
            //     new DownloadWebPageTask().execute("http://www.scom.co.in/Group1ReturnData.Aspx?NodeName="+Text);

              //   textView = (TextView) findViewById(R.id.txtCon);

                // try{
                    // if(textView.getFreezesText())
               //       msg=     textView.getText().toString();
                 //=====================================
                 populateGridwt();
               /*   
                */
                 //========================================
                //==========================================     

                      //  }

                 //catch(Exception e)
                 //{                                     
                    // textView.setText(e.toString());
                  //     textView.setVisibility(View.GONE);
                    // textView = (TextView) findViewById(R.id.txtCon);

               //  }

            }
                catch(NullPointerException e)
                {
                    textView.setText(e.toString());
                    textView = (TextView) findViewById(R.id.txtCon);

                }
            }

最后是最新的 logcat :-

11-06 12:35:14.161: W/dalvikvm(8438): threadid=1: thread exiting with uncaught exception (group=0x40c86258)
11-06 12:35:14.172: E/AndroidRuntime(8438): FATAL EXCEPTION: main
11-06 12:35:14.172: E/AndroidRuntime(8438): java.lang.NullPointerException
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.AbsSpinner.onMeasure(AbsSpinner.java:192)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.Spinner.onMeasure(Spinner.java:285)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.view.View.measure(View.java:12773)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.TableRow.getColumnsWidths(TableRow.java:310)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.TableLayout.findLargestCells(TableLayout.java:500)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.TableLayout.measureVertical(TableLayout.java:465)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.TableLayout.onMeasure(TableLayout.java:431)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.view.View.measure(View.java:12773)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4788)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1374)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:663)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:553)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.view.View.measure(View.java:12773)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4788)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.view.View.measure(View.java:12773)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:815)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:553)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.view.View.measure(View.java:12773)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4788)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2103)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.view.View.measure(View.java:12773)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1149)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2583)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.os.Looper.loop(Looper.java:137)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at android.app.ActivityThread.main(ActivityThread.java:4503)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at java.lang.reflect.Method.invokeNative(Native Method)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at java.lang.reflect.Method.invoke(Method.java:511)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:809)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:576)
11-06 12:35:14.172: E/AndroidRuntime(8438):     at dalvik.system.NativeStart.main(Native Method)
4

3 回答 3

1

问题出在这里：

textView.setText(e.toString());
textView = (TextView) findViewById(R.id.txtCon);

您textview在初始化之前将文本设置为。用这个替换上面的行： -

textView = (TextView) findViewById(R.id.txtCon);
textView.setText(e.toString());
于 2013-11-06T06:52:37.393 回答
0

我认为您没有初始化textView，在使用它之前初始化对象。

                textView = (TextView) findViewById(R.id.txtCon);
于 2013-11-06T06:48:22.680 回答
0

此错误是由尝试访问 null 的对象引起的。

根据我的理解，您尝试将 textView 对象中的文本设置为空。

例如：您试图在 DownloadWebPageTask 类的 onPostExecute 方法中设置 textView 的文本，但该 textView 对象为 NULL 。

于 2013-11-06T07:01:53.357 回答