I am attempting to integrate Mixpanel into a simple application using the instructions here . However I am getting an error that is causing my App to crash.
I have no syntax errors in my code (see below).
Android Activity:
package com.example.testmixpanel;
import org.json.JSONException;
import org.json.JSONObject;
import com.mixpanel.android.mpmetrics.MixpanelAPI;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends Activity {
public static final String MIXPANEL_TOKEN = "xxx"; //intentionally not shown
// Initialize the library with your
// Mixpanel project token, MIXPANEL_TOKEN, and a reference
// to your application context.
MixpanelAPI mixpanel =
MixpanelAPI.getInstance(this, MIXPANEL_TOKEN);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
JSONObject props = new JSONObject();
mixpanel.track("Plan Selected", props);
}
@Override
protected void onDestroy() {
mixpanel.flush();
super.onDestroy();
}
}
However, when I try to run the application I get this error:
0-09 16:36:31.575: E/AndroidRuntime(13192): FATAL EXCEPTION: main
10-09 16:36:31.575: E/AndroidRuntime(13192): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.testmixpanel/com.example.testmixpanel.MainActivity}: java.lang.NullPointerException
What could be the cause of this issue?
Full stack trace (for reference):
10-09 16:36:31.575: E/AndroidRuntime(13192): FATAL EXCEPTION: main
10-09 16:36:31.575: E/AndroidRuntime(13192): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.testmixpanel/com.example.testmixpanel.MainActivity}: java.lang.NullPointerException
10-09 16:36:31.575: E/AndroidRuntime(13192): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2219)
10-09 16:36:31.575: E/AndroidRuntime(13192): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2349)
10-09 16:36:31.575: E/AndroidRuntime(13192): at android.app.ActivityThread.access$700(ActivityThread.java:159)
10-09 16:36:31.575: E/AndroidRuntime(13192): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1316)
10-09 16:36:31.575: E/AndroidRuntime(13192): at android.os.Handler.dispatchMessage(Handler.java:99)
10-09 16:36:31.575: E/AndroidRuntime(13192): at android.os.Looper.loop(Looper.java:176)
10-09 16:36:31.575: E/AndroidRuntime(13192): at android.app.ActivityThread.main(ActivityThread.java:5419)
10-09 16:36:31.575: E/AndroidRuntime(13192): at java.lang.reflect.Method.invokeNative(Native Method)
10-09 16:36:31.575: E/AndroidRuntime(13192): at java.lang.reflect.Method.invoke(Method.java:525)
10-09 16:36:31.575: E/AndroidRuntime(13192): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1046)
10-09 16:36:31.575: E/AndroidRuntime(13192): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:862)
10-09 16:36:31.575: E/AndroidRuntime(13192): at dalvik.system.NativeStart.main(Native Method)
10-09 16:36:31.575: E/AndroidRuntime(13192): Caused by: java.lang.NullPointerException
10-09 16:36:31.575: E/AndroidRuntime(13192): at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:109)
10-09 16:36:31.575: E/AndroidRuntime(13192): at com.mixpanel.android.mpmetrics.MixpanelAPI.getInstance(MixpanelAPI.java:175)
10-09 16:36:31.575: E/AndroidRuntime(13192): at com.example.testmixpanel.MainActivity.<init>(MainActivity.java:22)
10-09 16:36:31.575: E/AndroidRuntime(13192): at java.lang.Class.newInstanceImpl(Native Method)
10-09 16:36:31.575: E/AndroidRuntime(13192): at java.lang.Class.newInstance(Class.java:1130)
10-09 16:36:31.575: E/AndroidRuntime(13192): at android.app.Instrumentation.newActivity(Instrumentation.java:1078)
10-09 16:36:31.575: E/AndroidRuntime(13192): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2210)
10-09 16:36:31.575: E/AndroidRuntime(13192): ... 11 more
EDIT:
public class MainActivity extends Activity {
public static final String MIXPANEL_TOKEN = "xxxxx";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MixpanelAPI mixpanel =
MixpanelAPI.getInstance(getApplicationContext(), MIXPANEL_TOKEN);
setContentView(R.layout.activity_main);
JSONObject props = new JSONObject();
mixpanel.track("Plan Selected", props);
}
@Override
protected void onDestroy() {
mixpanel.flush(); //how to call this as mixpanel is not a class variable?
super.onDestroy();
}
}
If you want to use the mixpanel on onDestroy you should instantiate it like this:
public class MainActivity extends Activity {
public static final String MIXPANEL_TOKEN = "xxxxx";
MixpanelAPI mixpanel;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mixpanel =
MixpanelAPI.getInstance(getApplicationContext(), MIXPANEL_TOKEN);
setContentView(R.layout.activity_main);
JSONObject props = new JSONObject();
mixpanel.track("Plan Selected", props);
}
(...)
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