问题
I am trying to generate a graph using achartengine which pulls the data from a database and populates the graph using the data. Following is the code that populates the graph. All tha data is stored in
"dataArraylist". This code populates the data into graph
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;
however when i try to compile it I get Null Exception error, following is the error that is received after null exception:
04-07 21:09:31.713: E/AndroidRuntime(4091): java.lang.IllegalStateException: Could not execute method of the activity
I am also having problems on passing on the data from one activity to the graph activity. An answer would be appreciated
Full log is:
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
Following code downloads the data from database:
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();
}
回答1:
Refer this LINK for achartengine
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);
}
Add the above method and call the below lines from your oncreate method
XYMultipleSeriesRenderer renderer = getBarDemoRenderer();
setChartSettings(renderer);
Intent intent = ChartFactory.getBarChartIntent(this, getBarDemoDataset(), renderer, Type.DEFAULT);
startActivity(intent);
来源：https://stackoverflow.com/questions/10264943/generating-graph-by-using-remote-data-from-database-on-achartengine