Question

我是新手当我连接到服务器以使用来自url的数据来绘制android API 4.4.2中的图形时，我有这个错误。我尝试修复此错误，但我不能告诉我如何解决此错误

这是我的代码

results = new ArrayList<Result>();
      new JSONAsyncTask().execute("http://phm.umr-lab.com/getdata1.php");

class JSONAsyncTask extends AsyncTask<String, Void, Boolean> {

        ProgressDialog dialog;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            dialog = new ProgressDialog(MainActivity.this);
            dialog.setMessage("Loading, please wait");
            dialog.setTitle("Connecting server");
            dialog.show();
            dialog.setCancelable(false);
        }

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


            try {

                //------------------>>
                HttpGet httppost = new HttpGet(urls[0]);
                HttpClient httpclient = new DefaultHttpClient();
                HttpResponse response = httpclient.execute(httppost);

                // StatusLine stat = response.getStatusLine();
                int status = response.getStatusLine().getStatusCode();

                if (status == 200) {
                    HttpEntity entity = response.getEntity();
                    String data = EntityUtils.toString(entity);


                    JSONObject jsono = new JSONObject(data);
                    JSONArray jarray = jsono.getJSONArray("result");

                    for (int i = 0; i < jarray.length(); i++) {
                        JSONObject object = jarray.getJSONObject(i);
                        Day = object.getString("Day");
                        pH = Float.parseFloat(object.getString("pHdata"));
                    }

                    Date.add(Day);
                    ph.add(pH);
                    return true;
                }

                //------------------>>

            } catch (ParseException e1) {
                e1.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return false;
        }

        protected void onPostExecute(Boolean result) {
            super.onPostExecute(result);
            dialog.cancel();
            if(result == false)
                Toast.makeText(getApplicationContext(), "Unable to fetch data from server", Toast.LENGTH_LONG).show();

        }
    }
        private void openChart(){
        int[] x = {0,1,2,3,4,5,6,7 };
        Float[] bar = ph.toArray(new Float[Date.size()]);   
        String[] Datr = Date.toArray(new String[Date.size()]);  
        // Creating an  XYSeries for Income
        //CategorySeries incomeSeries = new CategorySeries("Income");
        XYSeries incomeSeries = new XYSeries("Data");
        // Creating an  XYSeries for Income
        for(int i=0;i<x.length;i++){            
            incomeSeries.add(i,bar[i]);
        }
        // Creating a dataset to hold each series
        XYMultipleSeriesDataset dataset = new XYMultipleSeriesDataset();
        // Adding Income Series to the dataset
        dataset.addSeries(incomeSeries);    
        // Creating XYSeriesRenderer to customize incomeSeries
        XYSeriesRenderer incomeRenderer = new XYSeriesRenderer();
        incomeRenderer.setColor(Color.rgb(130, 130, 230));
        incomeRenderer.setFillPoints(true);
        incomeRenderer.setLineWidth(2);
        incomeRenderer.setDisplayChartValues(true);
        // Creating a XYMultipleSeriesRenderer to customize the whole chart
        XYMultipleSeriesRenderer multiRenderer = new XYMultipleSeriesRenderer();
        multiRenderer.setXLabels(0);
        multiRenderer.setChartTitle("pHdata");
        multiRenderer.setXTitle("pH 1-14");
        multiRenderer.setYTitle("Date");
        multiRenderer.setZoomButtonsVisible(true);              
        for(int i=0; i< x.length;i++){
            multiRenderer.addXTextLabel(i, Datr[i]);            
        }       
        // Adding incomeRenderer and expenseRenderer to multipleRenderer
        // Note: The order of adding dataseries to dataset and renderers to multipleRenderer
        // should be same
        multiRenderer.addSeriesRenderer(incomeRenderer);
        // Creating an intent to plot bar chart using dataset and multipleRenderer      
        Intent intent = ChartFactory.getBarChartIntent(getBaseContext(), dataset, multiRenderer, Type.DEFAULT);
        // Start Activity
        startActivity(intent);

这是我的错误

    threadid=1: thread exiting with uncaught exception(group=0x430d4140)
FATAL EXCEPTION: main
Process: in.wptrafficanalyzer.achartenginebarchart, PID: 15991
java.lang.ArrayIndexOutOfBoundsException: length=1; index=1
    at in.wptrafficanalyzer.achartenginebarchart.MainActivity.openChart(MainActivity.java:164)
    at in.wptrafficanalyzer.achartenginebarchart.MainActivity.access$0(MainActivity.java:151)
    at in.wptrafficanalyzer.achartenginebarchart.MainActivity$1.onClick(MainActivity.java:66)
    at android.view.View.performClick(View.java:4487)
    at android.view.View$PerformClick.run(View.java:18746)
at android.os.Handler.handleCallback(Handler.java:733)
    at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:149)
    at android.app.ActivityThread.main(ActivityThread.java:5077)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)
    at dalvik.system.NativeStart.main(Native Method)

Answer 1

您的代码中存在一些问题

首先是：

 for (int i = 0; i < jarray.length(); i++) {
      JSONObject object = jarray.getJSONObject(i);
      Day = object.getString("Day");
      pH = Float.parseFloat(object.getString("pHdata"));
 }
 Date.add(Day);
 ph.add(pH);

当您按照上面所示的方式执行此操作时，始终只添加json中的最后一个元素。如果要添加json中的所有元素，则必须在循环内部调用add方法

for (int i = 0; i < jarray.length(); i++) {
      JSONObject object = jarray.getJSONObject(i);
      Date.add(object.getString("Day"));
      ph.add(Float.parseFloat(object.getString("pHdata"));
 }

第二个问题是openChart()方法。你这样做的地方如下：

 int[] x = {0,1,2,3,4,5,6,7 };
 Float[] bar = ph.toArray(new Float[Date.size()]);   
 String[] Datr = Date.toArray(new String[Date.size()]);
 ...  

 for(int i=0;i<x.length;i++){            
     incomeSeries.add(i,bar[i]);
 }

 ...
 for(int i=0;i<x.length;i++){            
      multiRenderer.addXTextLabel(i, Datr[i])
 }

你永远不会检查x数组与bar和Datr数组的长度是否相同或最大 - 这是非常危险的。你应该这样做：

 int[] x = {0,1,2,3,4,5,6,7 };
 Float[] bar = ph.toArray(new Float[Date.size()]);   
 String[] Datr = Date.toArray(new String[Date.size()]);
 ...  
 int firstSize = Math.min(x.length, bar.length);
 for(int i=0;i<firstSize;i++){            
     incomeSeries.add(i,bar[i]);
 }

 ...
 int secondSize = Math.min(x.length, Datr.length);
 for(int i=0;i<secondSize;i++){            
      multiRenderer.addXTextLabel(i, Datr[i])
 }

现在你的解决方案将是安全的。

java.lang.ArrayIndexOutOfBoundsException：length = 1; index = 1如何修复它

1 个答案: