Add Items to a spinner - spinner

Question

I am trying to add items to a spinner but I get the error "Unfortunately my app has stopped working". I have created a string array in strings.xml in which I have some items. When the user selects the add item from the MainActivity an editText with a button appears and I want whatever is in the editText to be passed into the spinner. The spinner is in the activity_main.xml and I am working on addactivity.xml. How am I going to pass the new items from the EditText (in addactivity.xml and AddActivity.java) to the spinner in the MainActivity.java and activity_main.xml?
Here is my code:
public class AddActivity extends Activity{
Spinner spnr1;
EditText edtxAddActivity;
ArrayAdapter<String> spinnerAdapter;
Button btnAddActivity;
String[] actArray;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.addactivity);
addActivityButton();
}
public void addActivityButton() {
// TODO Auto-generated method stub
edtxAddActivity = (EditText) findViewById(R.id.etAddActivity);
spnr1 = (Spinner) findViewById(R.id.spinner1);
actArray = getResources().getStringArray(R.array.activities_array);
spinnerAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,actArray);
spinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spnr1.setAdapter(spinnerAdapter);
btnAddActivity= (Button) findViewById(R.id.btAddActivity);
btnAddActivity.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
String newactivity = "" + edtxAddActivity.getText().toString();
spinnerAdapter.add(newactivity);
spinnerAdapter.notifyDataSetChanged();
}
});
}
}
This is my strings.xml file:
<?xml version="1.0" encoding="utf-8"?>
<string name="app_name">MyAdroidApp</string>
<string name="activity_prompt">Choose an activity</string>
<string-array name="activities_array">
<item>5-a-side</item>
<item>Football</item>
<item>Basketball</item>
<item>Table Tennis</item>
<item>Add</item>
</string-array>
The errors displayed are the following.
07-24 14:08:43.397: E/AndroidRuntime(24798): FATAL EXCEPTION: main
07-24 14:08:43.397: E/AndroidRuntime(24798): Process: com.example.myAndroidApp, PID: 24798
07-24 14:08:43.397: E/AndroidRuntime(24798): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myAndroidApp/com.example.myAndroidApp.AddActivity}: java.lang.NullPointerException
07-24 14:08:43.397: E/AndroidRuntime(24798): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
07-24 14:08:43.397: E/AndroidRuntime(24798): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
07-24 14:08:43.397: E/AndroidRuntime(24798): at android.app.ActivityThread.access$800(ActivityThread.java:135)
07-24 14:08:43.397: E/AndroidRuntime(24798): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
07-24 14:08:43.397: E/AndroidRuntime(24798): at android.os.Handler.dispatchMessage(Handler.java:102)
07-24 14:08:43.397: E/AndroidRuntime(24798): at android.os.Looper.loop(Looper.java:136)
07-24 14:08:43.397: E/AndroidRuntime(24798): at android.app.ActivityThread.main(ActivityThread.java:5001)
07-24 14:08:43.397: E/AndroidRuntime(24798): at java.lang.reflect.Method.invokeNative(Native Method)
07-24 14:08:43.397: E/AndroidRuntime(24798): at java.lang.reflect.Method.invoke(Method.java:515)
07-24 14:08:43.397: E/AndroidRuntime(24798): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
07-24 14:08:43.397: E/AndroidRuntime(24798): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
07-24 14:08:43.397: E/AndroidRuntime(24798): at dalvik.system.NativeStart.main(Native Method)
07-24 14:08:43.397: E/AndroidRuntime(24798): Caused by: java.lang.NullPointerException
07-24 14:08:43.397: E/AndroidRuntime(24798): at com.example.myAndroidApp.AddActivity.addActivityButton(AddActivity.java:46)
07-24 14:08:43.397: E/AndroidRuntime(24798): at com.example.socialactivities.AddActivity.onCreate(AddActivity.java:33)
07-24 14:08:43.397: E/AndroidRuntime(24798): at android.app.Activity.performCreate(Activity.java:5231)
07-24 14:08:43.397: E/AndroidRuntime(24798): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
07-24 14:08:43.397: E/AndroidRuntime(24798): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
07-24 14:08:43.397: E/AndroidRuntime(24798): ... 11 more
The problem is that the spinnerAdapter produce a nullpointerexception because the listview is probably empty or not initialised. How can I initialise my array? My string-array is in array.xml in values.

Answer 1

NullPointerException at com.example.myAndroidApp.AddActivity.addActivityButton(AddActivity.java:46)
Means you are referecing and using something that is null at that moment. By the looks of it maybe it is one of your view references. My suggestion is put some debug checkpoints one each line of code and execute the application and follow step by step figuring out what is null

Answer 2

Take a look at R.layout.addactivity layout, you miss something , especially I think findViewById(R.id.etAddActivity); is null, means you don't have it in layout or smtg is wrong in it's namie, id or so