android - 设置刷新 Activity 图

Question

如下代码绘制图形如图

 public class MyActivity extends Activity {
          Prefs myprefs = null;
           private XYPlot mySimpleXYPlot;
           Number[] series1Numbers=new Number[10];
           Number[] series2Numbers=new Number[10];
           int a,b,c,d,ee,f,g;
        @Override
        public void onCreate(Bundle savedInstanceState)  {
             super.onCreate(savedInstanceState);
             setContentView(R.layout.graphval);

             // Initialize our XYPlot reference:
             mySimpleXYPlot = (XYPlot) findViewById(R.id.mySimpleXYPlot);

             // Create two arrays of y-values to plot:

             this.myprefs = new Prefs(getApplicationContext());

             ArrayList<HashMap<String, Object>> mylist = new ArrayList<HashMap<String, Object>>(); 
                JSONObject json = JSONfunctions.getJSONfromURL("............");


                  // decrement the time remaining and update the display

                     try{

                        JSONArray  earthquakes = json.getJSONArray("graphs");

                        for(int i=0;i<earthquakes.length();i++){                        
                            HashMap<String, Object> map = new HashMap<String, Object>();
                             JSONObject e = earthquakes.getJSONObject(i);


                         a = Integer.parseInt(e.getString("sensor_a"));
                         b = Integer.parseInt(e.getString("sensor_b"));
                         c = Integer.parseInt(e.getString("sensor_c"));
                         d = Integer.parseInt(e.getString("sensor_d"));
                         ee = Integer.parseInt(e.getString("sensor_e"));
                         f = Integer.parseInt(e.getString("sensor_f"));
                         g = Integer.parseInt(e.getString("sensor_g"));

                       }  






                        series1Numbers[0]=a;
                        series1Numbers[1]=b;
                        series1Numbers[2]=c;
                        series1Numbers[3]=d;
                        series1Numbers[4]=ee;
                        series1Numbers[5]=f;
                        series1Numbers[6]=g;

                       // Turn the above arrays into XYSeries:
                        XYSeries series1 = new SimpleXYSeries(
                                Arrays.asList(series1Numbers),          // SimpleXYSeries takes a List so turn our array into a List
                                SimpleXYSeries.ArrayFormat.Y_VALS_ONLY, // Y_VALS_ONLY means use the element index as the x value
                                "Series1");                             // Set the display title of the series

                        // Same as above, for series2
                        XYSeries series2 = new SimpleXYSeries(Arrays.asList(series2Numbers), SimpleXYSeries.ArrayFormat.Y_VALS_ONLY, 
                                "Series2");

                       // Create a formatter to use for drawing a series using LineAndPointRenderer:
                        LineAndPointFormatter series1Format = new LineAndPointFormatter(
                                Color.rgb(0, 200, 0),                   // line color
                                Color.rgb(0, 100, 0),                   // point color
                                Color.rgb(150, 190, 150));              // fill color (optional)

                        // Add series1 to the xyplot:
                        mySimpleXYPlot.addSeries(series1, series1Format);

                        // Same as above, with series2:
                        mySimpleXYPlot.addSeries(series2, new LineAndPointFormatter(Color.rgb(0, 0, 200), Color.rgb(0, 0, 100),
                                Color.rgb(150, 150, 190)));


                        // Reduce the number of range labels
                        mySimpleXYPlot.setTicksPerRangeLabel(3);

                        // By default, AndroidPlot displays developer guides to aid in laying out your plot.
                        // To get rid of them call disableAllMarkup():
                        mySimpleXYPlot.disableAllMarkup();





                     }catch(JSONException e)        {
                         Log.e("log_tag", "Error parsing data "+e.toString());
                     }

        } 

但是当你尝试通过以下代码每秒刷新图形时，它会弄乱整个图形，如图所示

public class MyActivity extends Activity {
    public int currentimageindex=0;
      Timer timer;
      TimerTask task;
       private XYPlot mySimpleXYPlot;
       Number[] series1Numbers=new Number[10];
       Number[] series2Numbers=new Number[10];
       int a,b,c,d,ee,f,g;
    @Override
    public void onCreate(Bundle savedInstanceState)  {
         super.onCreate(savedInstanceState);

         setContentView(R.layout.graphval);

         // Initialize our XYPlot reference:
         mySimpleXYPlot = (XYPlot) findViewById(R.id.mySimpleXYPlot);

         final Handler mHandler = new Handler();

         // Create runnable for posting
         final Runnable mUpdateResults = new Runnable() {
             public void run() {

                 AnimateandSlideShow();

             }
         };

         int delay = 1000; // delay for 1 sec.

         int period = 8000; // repeat every 4 sec.

         Timer timer = new Timer();

         timer.scheduleAtFixedRate(new TimerTask() {

         public void run() {

              mHandler.post(mUpdateResults);

         }

         }, delay, period);

     }

     public void onClick(View v) {

         finish();
         android.os.Process.killProcess(android.os.Process.myPid());
       }
    private void AnimateandSlideShow() {

          ArrayList<HashMap<String, Object>> mylist = new ArrayList<HashMap<String, Object>>(); 
          JSONObject json = JSONfunctions.getJSONfromURL("............");

           try{

            JSONArray  earthquakes = json.getJSONArray("graphs");

            for(int i=0;i<earthquakes.length();i++){                        
                HashMap<String, Object> map = new HashMap<String, Object>();
                 JSONObject e = earthquakes.getJSONObject(i);


             a = Integer.parseInt(e.getString("sensor_a"));
             b = Integer.parseInt(e.getString("sensor_b"));
             c = Integer.parseInt(e.getString("sensor_c"));
             d = Integer.parseInt(e.getString("sensor_d"));
             ee = Integer.parseInt(e.getString("sensor_e"));
             f = Integer.parseInt(e.getString("sensor_f"));
             g = Integer.parseInt(e.getString("sensor_g"));

           }  






            series1Numbers[0]=a;
            series1Numbers[1]=b;
            series1Numbers[2]=c;
            series1Numbers[3]=d;
            series1Numbers[4]=ee;
            series1Numbers[5]=f;
            series1Numbers[6]=g;

           // Turn the above arrays into XYSeries:
            XYSeries series1 = new SimpleXYSeries(
                    Arrays.asList(series1Numbers),          // SimpleXYSeries takes a List so turn our array into a List
                    SimpleXYSeries.ArrayFormat.Y_VALS_ONLY, // Y_VALS_ONLY means use the element index as the x value
                    "Series1");                             // Set the display title of the series

            // Same as above, for series2
            XYSeries series2 = new SimpleXYSeries(Arrays.asList(series2Numbers), SimpleXYSeries.ArrayFormat.Y_VALS_ONLY, 
                    "Series2");

           // Create a formatter to use for drawing a series using LineAndPointRenderer:
            LineAndPointFormatter series1Format = new LineAndPointFormatter(
                    Color.rgb(0, 200, 0),                   // line color
                    Color.rgb(0, 100, 0),                   // point color
                    Color.rgb(150, 190, 150));              // fill color (optional)

            // Add series1 to the xyplot:
            mySimpleXYPlot.addSeries(series1, series1Format);

            // Same as above, with series2:
            mySimpleXYPlot.addSeries(series2, new LineAndPointFormatter(Color.rgb(0, 0, 200), Color.rgb(0, 0, 100),
                    Color.rgb(150, 150, 190)));


            // Reduce the number of range labels
            mySimpleXYPlot.setTicksPerRangeLabel(3);

            // By default, AndroidPlot displays developer guides to aid in laying out your plot.
            // To get rid of them call disableAllMarkup():
            mySimpleXYPlot.disableAllMarkup();





           }catch(JSONException e)        {
             Log.e("log_tag", "Error parsing data "+e.toString());
           }

    }




}     

Answer 1

看起来 mySimpleXYPlot.disableAllMarkup() 没有被调用。我看到它包裹在一个 try catch 中。有 JSONException 吗？无论如何，这应该只在您创建 Activity 时调用一次。