java - 使用图表引擎上的数据库中的远程数据生成图形

Question

我正在尝试使用 achartengine 生成图表，它从数据库中提取数据并使用数据填充图表。以下是填充图表的代码。所有数据都存储在

“数据数组列表”。此代码将数据填充到图形中

        CategorySeries series = new CategorySeries("Bar Graph");     //"series" = graph
        for(int i=0; i< size; i++)
        {
            series.add("Bar"+(i+1), dataArraylist.get(i));                      //add each of the value to the series i.e graph
        }


        XYMultipleSeriesDataset dataset= new XYMultipleSeriesDataset(); 
        dataset.addSeries(series.toXYSeries());                                       //add the graph into a dataset


        // customisation for the first line
        XYSeriesRenderer renderer = new XYSeriesRenderer();
        renderer.setDisplayChartValues(true);
        renderer.setChartValuesSpacing((float) 0.5);
        renderer.setColor(Color.WHITE);

        XYMultipleSeriesRenderer mRenderer = new XYMultipleSeriesRenderer(); //create a new renderer.
        mRenderer.addSeriesRenderer(renderer); //renderer lets one to change the proerties of the graph i.e line colour etc
        mRenderer.setXTitle("X VALUES");
        mRenderer.setXTitle("Y VALUES");

        mRenderer.setChartTitle("This is title");

        Intent intent = ChartFactory.getBarChartIntent(context, dataset, mRenderer,Type.DEFAULT, "Title"); //package the whole chart together


        return intent;

然而，当我尝试编译它时，出现空异常错误，以下是空异常后收到的错误:

                       04-07 21:09:31.713: E/AndroidRuntime(4091): java.lang.IllegalStateException: Could not execute method of the activity

我在将数据从一个 Activity 传递到图形 Activity 时也遇到了问题。一个答案将不胜感激

完整的日志是:

                   04-07 21:09:31.674: D/AndroidRuntime(4091): Shutting down VM
04-07 21:09:31.674: W/dalvikvm(4091): threadid=1: thread exiting with uncaught exception (group=0x40015560)
04-07 21:09:31.713: E/AndroidRuntime(4091): FATAL EXCEPTION: main
04-07 21:09:31.713: E/AndroidRuntime(4091): java.lang.IllegalStateException: Could not execute method of the activity
04-07 21:09:31.713: E/AndroidRuntime(4091):     at android.view.View$1.onClick(View.java:2144)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at android.view.View.performClick(View.java:2485)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at android.view.View$PerformClick.run(View.java:9080)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at android.os.Handler.handleCallback(Handler.java:587)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at android.os.Handler.dispatchMessage(Handler.java:92)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at android.os.Looper.loop(Looper.java:123)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at android.app.ActivityThread.main(ActivityThread.java:3683)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at java.lang.reflect.Method.invokeNative(Native Method)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at java.lang.reflect.Method.invoke(Method.java:507)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at dalvik.system.NativeStart.main(Native Method)
04-07 21:09:31.713: E/AndroidRuntime(4091): Caused by: java.lang.reflect.InvocationTargetException
04-07 21:09:31.713: E/AndroidRuntime(4091):     at java.lang.reflect.Method.invokeNative(Native Method)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at java.lang.reflect.Method.invoke(Method.java:507)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at android.view.View$1.onClick(View.java:2139)
04-07 21:09:31.713: E/AndroidRuntime(4091):     ... 11 more
04-07 21:09:31.713: E/AndroidRuntime(4091): Caused by: java.lang.NullPointerException
04-07 21:09:31.713: E/AndroidRuntime(4091):     at hudds.fc.coach.ReadinessGraph.getIntent(ReadinessGraph.java:45)
04-07 21:09:31.713: E/AndroidRuntime(4091):     at hudds.fc.coach.Overview.generateGraph(Overview.java:101)
04-07 21:09:31.713: E/AndroidRuntime(4091):     ... 14 more
04-07 21:09:34.746: I/Process(4091): Sending signal. PID: 4091 SIG: 9

以下代码从数据库下载数据:

        try {
        if (json.getString(KEY_SUCCESS) != null) {

            String getsize=json.getString("size");
            size = Integer.parseInt(getsize);

            for (int i = 0; i < size; i++) { 
            String getRating=json.getJSONArray("number").getJSONObject(i).getString("rating_number");
            int rating = Integer.parseInt(getRating);


            readinessRatng.add(rating);
            String printratings=readinessRatng.toString();
            Log.e("ratings are", printratings);
            }

        }


    else{

                     }
        }

    catch (JSONException e) {
        e.printStackTrace();
            }

Answer 1

引用这个LINK对于图表引擎

 public XYMultipleSeriesRenderer getBarDemoRenderer() {
    XYMultipleSeriesRenderer renderer = new XYMultipleSeriesRenderer();
    renderer.setAxisTitleTextSize(16);
    renderer.setChartTitleTextSize(20);
    renderer.setLabelsTextSize(15);
    renderer.setLegendTextSize(15);
    renderer.setMargins(new int[] {20, 30, 15, 0});
    SimpleSeriesRenderer r = new SimpleSeriesRenderer();
    r.setColor(Color.BLUE);
    renderer.addSeriesRenderer(r);
    r = new SimpleSeriesRenderer();
    r.setColor(Color.GREEN);
    renderer.addSeriesRenderer(r);
    return renderer;
  }

 private XYMultipleSeriesDataset getBarDemoDataset() {
    XYMultipleSeriesDataset dataset = new XYMultipleSeriesDataset();
    final int nr = 10;
    Random r = new Random();
    for (int i = 0; i < SERIES_NR; i++) {
      CategorySeries series = new CategorySeries("Demo series " + (i + 1));
      for (int k = 0; k < nr; k++) {
        series.add(100 + r.nextInt() % 100);
      }
      dataset.addSeries(series.toXYSeries());
    }
    return dataset;
  }



private void setChartSettings(XYMultipleSeriesRenderer renderer) {
    renderer.setChartTitle("Chart demo");
    renderer.setXTitle("x values");
    renderer.setYTitle("y values");
    renderer.setXAxisMin(0);
    renderer.setXAxisMax(5);
    renderer.setYAxisMin(0);
    renderer.setYAxisMax(250);
  }

添加上述方法并从您的 oncreate 方法中调用以下行

XYMultipleSeriesRenderer renderer = getBarDemoRenderer();
setChartSettings(renderer);
Intent intent = ChartFactory.getBarChartIntent(this, getBarDemoDataset(), renderer, Type.DEFAULT);
startActivity(intent);