I am mainly looking for clarification and advice on this. In the app I am working on I setup a fragment for handling some basic controls and text, and moved the necessary XML from the activities layout file into the fragments layout file, without making any changes. However now when I run the app I get a NULLPOINTEREXCEPTION and it seems to be caused at line 19 in my GameStart activty when I try to set the textView by its ID. I have not changed the ID, only moved it to the fragment layout file, so I have two questions:
1) What exactly is the reason this is happening, because something similar happened before that I resolved but I don't see the reason it was happening in the reference docs on Android Developers
2) Any advice on how to fix this
Below is the GameStart activity, LogCat with the error, and the XML files in question. Thanks in advance, I've spent 2 hours now trying to find this answer.
EDITED FILES/LOGCAT BELOW
LogCat:
12-04 13:48:06.322 826-826/com.saphiric.simproject E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.saphiric.simproject/com.saphiric.simproject.GameStart}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2137)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:109)
at com.saphiric.simproject.GameStart.<init>(GameStart.java:25)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1130)
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2128)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Starting Activity (The error occurs when the app tries to start the GameStart activity):
package com.saphiric.simproject;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
public class TitleMenu extends ActionBarActivity {
public void startGame(View view){
Intent gameStart = new Intent(this, GameStart.class);
startActivity(gameStart);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActionBar actionBar = getSupportActionBar();
actionBar.hide();
setContentView(R.layout.activity_main_menu);
}
}
Fragment XML
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- Relative layout to handle main interaction area -->
<RelativeLayout
android:id="@+id/relativeLayout"
android:layout_width="wrap_content"
android:layout_height="90dp"
android:layout_alignParentBottom="true"
android:background="@drawable/bg_text">
<TextView
android:id="@id/storyText"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:text="@string/story_opening_one"
android:textColor="@color/black" />
<Button
android:id="@+id/advanceButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@id/controlsFragment"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:background="@drawable/button_advance"
android:onClick="advanceGame" />
<Button
android:id="@+id/menuButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:layout_below="@id/advanceButton"
android:background="@drawable/menu_button" />
</RelativeLayout>
</RelativeLayout>
Fragment Class:
package com.saphiric.simproject;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* Created by Saphiric on 12/4/14.
*/
public class ControlsFragment extends Fragment {
/**
* Fragment Lifecycle Methods
*/
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
// Inflates the layout resource for the fragment
return inflater.inflate(R.layout.controls_fragment, container, false);
}
@Override
public void onPause(){
}
}
GameStart activity:
package com.saphiric.simproject;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
/**
* Created by Saphiric on 11/12/14.
*/
public class GameStart extends Activity{
/**
* Necessary activity variables
*/
protected int clickCount = 0;
TextView storyText = (TextView) findViewById(R.id.storyText);
/**
* Sets up and alert dialogue builder for making decisions
* This will need to be revised during production
*/
AlertDialog.Builder decisionTime = new AlertDialog.Builder(getApplicationContext());
/**
* Handles advancing non character based conversations at the beginning
* of the story.
* If the player decides to investigate the scream, then the app loads the appropriate activity, and the same with the
* decision to leave the scene.
*/
public void advanceGame(View view){
clickCount = clickCount + 1; // Increments clickCount by 1 per click
if (clickCount == 1){
storyText.setText(R.string.story_opening_two);
} else if(clickCount == 2){
decisionTime.setTitle("Decision Time!"); // Sets the title for the decision box
decisionTime.setCancelable(false); // Sets it so that the decision can not be cancelled.
decisionTime.setPositiveButton("Investigate",new DialogInterface.OnClickListener() { // Sets up the positive button
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
decisionTime.setNegativeButton("Leave the scene.",new DialogInterface.OnClickListener() { // Sets up the negative button
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
}
}
/**
* Android activity methods
* @param savedInstanceState is the apps savedInstanceState
*/
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game_start);
}
}
GameStart Layout XML:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/bg_school_gate"
android:orientation="vertical">
<fragment
android:id="@+id/controlsFragment"
android:name="com.saphiric.simproject.ControlsFragment"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
tools:layout="@layout/controls_fragment" />
</RelativeLayout>
