NullPointerException with string-array in Spinner

Question

First app and so really new at android (played around about a year ago but nothing came of it), decent at programming. Wanting to make sure app renders on a phone, no functionality atm. Compiles fine, no problems there. Push it to my phone and "Unfortunately, Splitr has stopped".

Edit - added to the MainActivity.java, edits have * before and after (not in actual code) but now it flags

adapter.setDropDownViewResource(android.R.layout.activity_main);
// Apply the adapter to the spinner
spinnerSplit.setAdapter(adapter);

saying Error:(18, 36) identifier expected

setDropDownViewResource, activity_main and setAdapter all in red

Android Studio
Moto G - CM11 4.4.4

Here is the code, let me know if I missed anything out.

MainActivity.java

package com.hydr0dr4gon.splitrv2;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
*import android.widget.ArrayAdapter;
import android.widget.Spinner;*


public class MainActivity extends Activity {

    *Spinner spinnerSplit = (Spinner) findViewById(R.id.spinner);
// Create an ArrayAdapter using the string array and a default spinner layout
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
        R.array.arraySplitr, android.R.layout.simple_spinner_item);
// Specify the layout to use when the list of choices appears
adapter.setDropDownViewResource(android.R.layout.activity_main);
// Apply the adapter to the spinner
spinnerSplit.setAdapter(adapter);*

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
 }
}

SplitrDialogFragment.java

package com.hydr0dr4gon.splitrv2;

import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.content.DialogInterface;
import android.os.Bundle;

public class SplitrDialogFragment extends DialogFragment {

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    // Use the Builder class for convenient dialog construction
    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());

    builder.setMessage(R.string.dialog_split_pay)
            .setNegativeButton(R.string.OK, new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    // User cancelled the dialog
                }
            });

    // Create the AlertDialog object and return it
    return builder.create();
 }
}

Strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="app_name">Splitr</string>
    <string name="hello_world">Hello world!</string>
    <string name="action_settings">Settings</string>
    <string name="btnSplit">Split</string>
    <string name="btnTip">+ Tip</string>
    <string name="txtSplit">Split By</string>
    <string name="txtHint">Enter Bill Total</string>
    <string name="spinnerSplit">No. of People</string>
    <string name="dialog_split_pay">Each Person Pays</string>
    <string name="OK">OK</string>

<array name="arraySplitr">
    <item>2</item>
    <item>3</item>
    <item>4</item>
    <item>5</item>
    <item>6</item>
    <item>7</item>
    <item>8</item>
    <item>9</item>
    <item>10</item>
</array>

actvity_main.xml

RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="com.hydr0dr4gon.splitr.MainActivity">

<TableLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_alignParentTop="true"
    android:layout_alignParentStart="true"
    android:paddingLeft="40dp"
    android:paddingTop="80dp"
    android:paddingRight="40dp"
    android:paddingBottom="80dp">

    <TableRow
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">

        <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_span="2"
            android:inputType="number"
            android:ems="10"
            android:id="@+id/editText"
            android:layout_column="0"
            android:layout_weight="1.5"
            android:hint="@string/txtHint" />

    </TableRow>

    <TableRow
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">

        <TextView
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:text="@string/txtSplit"
            android:id="@+id/txtSplit"
            android:layout_weight="1"
            android:textSize="32dp"
            android:textAlignment="center"
            android:gravity="center" />

        <Spinner
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:id="@+id/spinner"
            android:layout_weight="1"
            android:spinnerStyle="@android:style/Widget.Spinner.DropDown"
            android:textAlignment="center"
            android:entries="@array/arraySplitr"
            android:prompt="@string/spinnerSplit"/>

    </TableRow>

    <TableRow
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">

        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/btnTip"
            android:id="@+id/btnTip"
            android:layout_weight="1" />

        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/btnSplit"
            android:id="@+id/btnSplit"
            android:layout_weight="1" />
    </TableRow>

</TableLayout>

logcat

> 07-11 21:18:50.899  10290-10290/com.hydr0dr4gon.splitrv2 D/ActivityThread﹕ handleBindApplication:com.hydr0dr4gon.splitrv2
07-11 21:18:50.899  10290-10290/com.hydr0dr4gon.splitrv2 D/ActivityThread﹕ setTargetHeapUtilization:0.75
07-11 21:18:50.899  10290-10290/com.hydr0dr4gon.splitrv2 D/ActivityThread﹕ setTargetHeapMinFree:2097152
07-11 21:18:51.198  10290-10290/com.hydr0dr4gon.splitrv2 D/AndroidRuntime﹕ Shutting down VM
07-11 21:18:51.206  10290-10290/com.hydr0dr4gon.splitrv2 E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.hydr0dr4gon.splitrv2, PID: 10290
    java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
            at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
            at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
            at android.widget.AbsSpinner.onMeasure(AbsSpinner.java:193)
            at android.widget.Spinner.onMeasure(Spinner.java:482)
            at android.view.View.measure(View.java:16521)
            at android.widget.TableRow.getColumnsWidths(TableRow.java:312)
            at android.widget.TableLayout.findLargestCells(TableLayout.java:508)
            at android.widget.TableLayout.measureVertical(TableLayout.java:473)
            at android.widget.TableLayout.onMeasure(TableLayout.java:439)
            at android.view.View.measure(View.java:16521)
            at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:719)
            at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:455)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
            at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:327)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
            at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2552)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1912)
            at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1109)
            at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1291)
            at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:996)
            at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5600)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
            at android.view.Choreographer.doCallbacks(Choreographer.java:574)
            at android.view.Choreographer.doFrame(Choreographer.java:544)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5137)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:611)

Thanks.

Answer 1

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
    at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
    at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
    at android.widget.AbsSpinner.onMeasure(AbsSpinner.java:193)
    at android.widget.Spinner.onMeasure(Spinner.java:482)

This tells you that the error was measuring the Spinner. More exactly, one of the strings that should be displayed inside it is null.

The most likely cause is a problem with the @array/arraySplitr resource. Is it a valid string-array resource as defined in the documentation?

This:

<array name="arraySplitr">
    <item>2</item>
    ...

should be instead:

<string-array name="arraySplitr">
    <item>2</item>
    ...

The array element is for Typed Arrays. String arrays must use string-array.

Answer 2

Your logcat has a NullPointerException.

E/AndroidRuntime﹕ FATAL EXCEPTION: main Process: com.hydr0dr4gon.splitrv2, PID: 10290 java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)

Something is not initialized. From your code I cannot see what it would be. Do you have an ArrayAdapter and if so you you initialize it and all the objects it contains? Or is your table just filled by your layout file? I would start looking at how your table is filled (based on the logcat) but I can't see specifically what the problem would be from the code you posted.