[Java for Android App Development] DarkMethod:
Hello there,

I am trying to learn android application development through one of the online tutorials .I am stuck at a point and since,both java and android are new for me I can't figure out how to get out of it.Here's the code to my Startingpoint.java:

public class Startingpoint extends Activity {
int counter;
Button add,sub;
TextView display;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
counter=0;
add=(Button)findViewById(R.id.bAdd);
sub=(Button)findViewById(R.id.bSub);
display=(TextView)findViewById(R.id.display);
add.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
counter++;
display.setText("Your total is " + counter);

}
});
sub.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
counter--;
display.setText("Your total is" + counter);

}
});
}

}

The following are the contents within the LineaLlayout in my main.xml file:

<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/result"
android:textSize="25sp"
android:layout_gravity="fill_horizontal"
android:gravity="center"
android:id="@+id/display"
/>
<Button
android:layout_width="250dp"
android:layout_height="wrap_content"
android:text="@string/bAdd"
android:layout_gravity="center"
android:gravity="center"
android:id="@+id/bAdd"
/>
<Button
android:layout_width="250dp"
android:layout_height="wrap_content"
android:text="@string/bSub"
android:layout_gravity="center"
android:gravity="center"
android:id="@+id/bSub"
/>

And this is what the logcat has to say :

02-13 11:44:12.076: D/AndroidRuntime(2026): Shutting down VM
02-13 11:44:12.076: W/dalvikvm(2026): threadid=1: thread exiting with uncaught exception (group=0xb2d5bb08)
02-13 11:44:12.156: E/AndroidRuntime(2026): FATAL EXCEPTION: main
02-13 11:44:12.156: E/AndroidRuntime(2026): Process: com.thenewboston.rohit, PID: 2026
02-13 11:44:12.156: E/AndroidRuntime(2026): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.thenewboston.rohit/com.thenewboston.rohit.Startingpoint}: java.lang.NullPointerException
02-13 11:44:12.156: E/AndroidRuntime(2026):	at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2176)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at android.app.ActivityThread.access$700(ActivityThread.java:135)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at android.os.Handler.dispatchMessage(Handler.java:102)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at android.os.Looper.loop(Looper.java:137)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at android.app.ActivityThread.main(ActivityThread.java:4998)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at java.lang.reflect.Method.invokeNative(Native Method)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at java.lang.reflect.Method.invoke(Method.java:515)
02-13 11:44:12.156: E/AndroidRuntime(2026):	atcom.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at dalvik.system.NativeStart.main(Native Method)
02-13 11:44:12.156: E/AndroidRuntime(2026): Caused by: java.lang.NullPointerException
02-13 11:44:12.156: E/AndroidRuntime(2026):	at com.thenewboston.rohit.Startingpoint.onCreate(Startingpoint.java:21)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at android.app.Activity.performCreate(Activity.java:5243)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
02-13 11:44:12.156: E/AndroidRuntime(2026):	at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2140)
02-13 11:44:12.156: E/AndroidRuntime(2026):	... 11 more

Being inexperienced in java , I could not figure out what's wrong with the code.May be the exception is due to my add,sub and display being null but I am not sure.Please help me figure out what's wrong with my code and how to deal with it.

Any help is greatly appreciated.