我正在使用MPAndroidChart解析条形图中的json数据，同时在第一次运行程序运行perfeclty时运行程序但是如果我再次在同一个碎片应用程序中崩溃，而搜索我知道因为getActivity null指针运行任何suggetion如何解决它。我的代码是。
final RequestQueue requestQueue = Volley.newRequestQueue(getContext());
final JsonObjectRequest jsonObjectRequest=new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
final List<BarEntry> yEntrys = new ArrayList<>();
Log.d(TAG, response.toString());
Gson gson = new Gson();
SiteStatistics siteStatistics = gson.fromJson(response.toString(), SiteStatistics.class);
try {
String activitiesCount = siteStatistics.getActivitiesSeen();
String theftsCount = siteStatistics.getTheftsAverted();
String arrestsCount = siteStatistics.getArrests();
String alaramsCount = siteStatistics.getOutputs();
String missedCount = siteStatistics.getMissed();
yEntrys.add(new BarEntry(0f, Integer.parseInt(activitiesCount)));
yEntrys.add(new BarEntry(1f, Integer.parseInt(theftsCount)));
yEntrys.add(new BarEntry(2f, Integer.parseInt(arrestsCount)));
yEntrys.add(new BarEntry(3f, Integer.parseInt(alaramsCount)));
yEntrys.add(new BarEntry(4f, Integer.parseInt(missedCount)));
} catch (Exception e) {
e.getMessage();
}
/*BarDataSet set1;
if (mChart.getData() != null &&
mChart.getData().getDataSetCount() > 0) {
set1 = (BarDataSet) mChart.getData().getDataSetByIndex(0);
set1.setValues(yVals1);
mChart.getData().notifyDataChanged();
mChart.notifyDataSetChanged();
mChart.invalidate();
} else {
set1 = new BarDataSet(yVals1, "The year 2017");
set1.setDrawIcons(false);
set1.setColors(ColorTemplate.MATERIAL_COLORS);
ArrayList<IBarDataSet> dataSets = new ArrayList<IBarDataSet>();
dataSets.add(set1);
BarData data = new BarData(dataSets);
data.setValueTextSize(10f);
data.setBarWidth(0.9f);
mChart.setData(data);*/
BarDataSet set1;
set1 = new BarDataSet(yEntrys,"");
set1.setBarBorderWidth(1f);
set1.setDrawIcons(false);
ArrayList<IBarDataSet> dataSets = new ArrayList<IBarDataSet>();
dataSets.add(set1);
ArrayList<Integer> colors = new ArrayList<Integer>();
colors.add(ContextCompat.getColor(getActivity(),android.R.color.holo_blue_bright));
colors.add(ContextCompat.getColor(getActivity(),android.R.color.holo_purple));
colors.add(ContextCompat.getColor(getActivity(),android.R.color.holo_green_dark));
colors.add(ContextCompat.getColor(getActivity(),android.R.color.holo_red_dark));
colors.add(ContextCompat.getColor(getActivity(),android.R.color.holo_orange_light));
set1.setColors(colors);
//set1.setColors(ColorTemplate.VORDIPLOM_COLORS);
/*set1.setColors(new int[]
{
R.color.activities, R.color.theft_averted, R.color.missed,
R.color.armed_activated, R.color.arrests
}, getActivity());*/
mChart.setExtraBottomOffset(0);
BarData data = new BarData(dataSets);
data.setBarWidth(0.9f);
data.setValueFormatter(new MyValueFormatter());
XAxis xAxis = mChart.getXAxis();
//IAxisValueFormatter xAxisFormatter = new MyXAxisValueFormatter(mChart);
//xAxis.setValueFormatter(xAxisFormatter);
xAxis.setPosition(XAxis.XAxisPosition.BOTTOM);
xAxis.setLabelRotationAngle(30);
xAxis.setSpaceMax(5f);
xAxis.setGranularity(1f);
xAxis.setLabelCount(5);
xAxis.setDrawGridLines(false);
xAxis.setGranularityEnabled(true);
Legend l= mChart.getLegend();
l.setVerticalAlignment(Legend.LegendVerticalAlignment.BOTTOM);
l.setHorizontalAlignment(Legend.LegendHorizontalAlignment.LEFT);
l.setOrientation(Legend.LegendOrientation.HORIZONTAL);
l.setDrawInside(false);
l.setForm(Legend.LegendForm.SQUARE);
l.setFormSize(9f);
l.setTextSize(11f);
l.setXEntrySpace(4f);
LegendEntry l1=new LegendEntry("Activities", Legend.LegendForm.DEFAULT,10f,2f,null, ContextCompat.getColor(getActivity(),android.R.color.holo_blue_bright));
LegendEntry l2=new LegendEntry("ArmedActivated", Legend.LegendForm.DEFAULT,10f,2f,null, ContextCompat.getColor(getActivity(),android.R.color.holo_purple));
LegendEntry l3=new LegendEntry("Theft Averted", Legend.LegendForm.DEFAULT,10f,1f,null,ContextCompat.getColor(getActivity(),android.R.color.holo_green_dark));
LegendEntry l4=new LegendEntry("Arrest", Legend.LegendForm.DEFAULT,10f,2f,null, ContextCompat.getColor(getActivity(),android.R.color.holo_red_dark));
LegendEntry l5=new LegendEntry("Missed", Legend.LegendForm.DEFAULT,10f,2f,null, ContextCompat.getColor(getActivity(),android.R.color.holo_orange_light));
mChart.setFitBars(true);
l.setEnabled(true);
l.setWordWrapEnabled(true);
l.setCustom(new LegendEntry[]{l1,l2,l3,l4,l5});
mChart.setData(data);
mChart.invalidate();
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error)
{
Toast.makeText(getContext(), error.toString(), Toast.LENGTH_SHORT).show();
}
});
requestQueue.add(jsonObjectRequest);
我的日志是。
java.lang.NullPointerException: Attempt to invoke virtual method 'int android.content.Context.getColor(int)' on a null object reference
at android.support.v4.content.ContextCompat.getColor(ContextCompat.java:409)
at com.ivigil.ivis.fragments.CurrentFragment$1.onResponse(CurrentFragment.java:214)
at com.ivigil.ivis.fragments.CurrentFragment$1.onResponse(CurrentFragment.java:155)
at com.android.volley.toolbox.JsonRequest.deliverResponse(JsonRequest.java:83)
at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:106)
at android.os.Handler.handleCallback(Handler.java:789)
at android.os.Handler.dispatchMessage(Handler.java:98)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)