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Null pointer exception on CursorAdapter

I am getting a NullPointerException. Below you can find my Logcat and the relevant code.
Logcat:
12-23 00:17:35.330: E/AndroidRuntime(2019): FATAL EXCEPTION: main
12-23 00:17:35.330: E/AndroidRuntime(2019): Process: com.android.timesheet, PID: 2019
12-23 00:17:35.330: E/AndroidRuntime(2019): java.lang.NullPointerException
12-23 00:17:35.330: E/AndroidRuntime(2019): at com.android.timesheet.adapter.CustomCursorAdapter$1.onClick(CustomCursorAdapter.java:54)
12-23 00:17:35.330: E/AndroidRuntime(2019): at android.view.View.performClick(View.java:4438)
12-23 00:17:35.330: E/AndroidRuntime(2019): at android.view.View$PerformClick.run(View.java:18422)
12-23 00:17:35.330: E/AndroidRuntime(2019): at android.os.Handler.handleCallback(Handler.java:733)
12-23 00:17:35.330: E/AndroidRuntime(2019): at android.os.Handler.dispatchMessage(Handler.java:95)
12-23 00:17:35.330: E/AndroidRuntime(2019): at android.os.Looper.loop(Looper.java:136)
12-23 00:17:35.330: E/AndroidRuntime(2019): at android.app.ActivityThread.main(ActivityThread.java:5017)
12-23 00:17:35.330: E/AndroidRuntime(2019): at java.lang.reflect.Method.invokeNative(Native Method)
12-23 00:17:35.330: E/AndroidRuntime(2019): at java.lang.reflect.Method.invoke(Method.java:515)
12-23 00:17:35.330: E/AndroidRuntime(2019): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
12-23 00:17:35.330: E/AndroidRuntime(2019): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
12-23 00:17:35.330: E/AndroidRuntime(2019): at dalvik.system.NativeStart.main(Native Method)
CustomCursorAdapter.java:
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.CursorAdapter;
import android.widget.TextView;
import com.android.timesheet.ModifyMember;
import com.android.timesheet.R;
public class CustomCursorAdapter extends CursorAdapter {
Button delete_btn;
TextView memID_tv, memName_tv;
#SuppressWarnings("deprecation")
public CustomCursorAdapter(Activity context, Cursor c) {
super(context, c);
}
#Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
// when the view will be created for first time,
// we need to tell the adapters, how each item will look
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
View retView = inflater.inflate(R.layout.single_row_item, parent, false);
return retView;
}
#Override
public void bindView(View view, final Context context, Cursor cursor) {
// here we are setting our data
// that means, take the data from the cursor and put it in views
TextView textViewPersonName = (TextView) view.findViewById(R.id.tv_person_name);
textViewPersonName.setText(cursor.getString(cursor.getColumnIndex(cursor.getColumnName(1))));
delete_btn=(Button)view.findViewById(R.id.delete_btn);
delete_btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
memID_tv = (TextView)v.findViewById(R.id.member_id);
memName_tv = (TextView)v.findViewById(R.id.member_name);
String memberID_val = memID_tv.getText().toString();; ---->54th Line
String memberName_val = memName_tv.getText().toString();
Intent i = new Intent(context,
ModifyMember.class);
i.putExtra("memberName", memberName_val);
i.putExtra("memberID", memberID_val);
((Activity)context).startActivity(i);
}
});
}
}
I am using a delete button to delete all the listview row items. At that point I am getting the NullPointerException.

Use view(view of row) instead of v parameter of onClick method which is view of Button :
delete_btn=(Button)view.findViewById(R.id.delete_btn);
delete_btn.setTag(view);
delete_btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
View rowview=(View)v.getTag();
memID_tv = (TextView)rowview.findViewById(R.id.member_id);
memName_tv = (TextView)rowview.findViewById(R.id.member_name);
}
});

Use view instead of v
memID_tv = (TextView)view.findViewById(R.id.member_id);
In bindview try this-
if (view == null) {
view = inflater.inflate(R.layout.single_row_item, parent, null);
}
TextView textViewPersonName = (TextView) view.findViewById(R.id.tv_person_name);
textViewPersonName.setText(cursor.getString(cursor.getColumnIndex(cursor.getColumnName(1))));
delete_btn=(Button)view.findViewById(R.id.delete_btn);
.
.
.

you are getting the view from clicked view, but you have to get the views from the root view.
memID_tv = (TextView)v. findViewById(R.id.member_id);
memName_tv = (TextView)v.findViewById(R.id.member_name);
change these lines into this:
memID_tv = (TextView)view. findViewById(R.id.member_id);
memName_tv = (TextView)view.findViewById(R.id.member_name);

Simple Android App wont run [duplicate]

This question already has answers here:
NullPointerException accessing views in onCreate()
(13 answers)
Closed 8 years ago.
Whenever I try to run my Android app made in Eclipse it gives me Has stopped working.
It's a simple button and text view text setting. Here is my code.
package com.example.polidoesnttwantacracker;
import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
private static final Button Button = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView v = (TextView)findViewById(R.id.Maikati);
v.setText("Welcome you Dick.");
Button but = (Button)findViewById(R.id.ButtonaNaMaikaTi);
but.setText("WTF");
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
}
The xml file as requested.
<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:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.polidoesnttwantacracker.MainActivity$PlaceholderFragment" >
<TextView
android:id="#+id/Maikati"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="149dp"
android:text="" />
<Button
android:id="#+id/ButtonaNaMaikaTi"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/Maikati"
android:layout_centerHorizontal="true"
android:text="OK" />
</RelativeLayout>
So if you can please help me. It's really frustrating and I can't go on with my lections if i don't get it running.
Here is the cat log that it gives me :D
06-01 19:05:28.438: E/Trace(2561): error opening trace file: No such file or directory (2)
06-01 19:05:28.534: D/AndroidRuntime(2561): Shutting down VM
06-01 19:05:28.534: W/dalvikvm(2561): threadid=1: thread exiting with uncaught exception (group=0xa61f4908)
06-01 19:05:28.538: E/AndroidRuntime(2561): FATAL EXCEPTION: main
06-01 19:05:28.538: E/AndroidRuntime(2561): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.polidoesnttwantacracker/com.example.polidoesnttwantacracker.MainActivity}: java.lang.NullPointerException
06-01 19:05:28.538: E/AndroidRuntime(2561): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
06-01 19:05:28.538: E/AndroidRuntime(2561): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
06-01 19:05:28.538: E/AndroidRuntime(2561): at android.app.ActivityThread.access$600(ActivityThread.java:141)
06-01 19:05:28.538: E/AndroidRuntime(2561): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
06-01 19:05:28.538: E/AndroidRuntime(2561): at android.os.Handler.dispatchMessage(Handler.java:99)
06-01 19:05:28.538: E/AndroidRuntime(2561): at android.os.Looper.loop(Looper.java:137)
06-01 19:05:28.538: E/AndroidRuntime(2561): at android.app.ActivityThread.main(ActivityThread.java:5041)
06-01 19:05:28.538: E/AndroidRuntime(2561): at java.lang.reflect.Method.invokeNative(Native Method)
06-01 19:05:28.538: E/AndroidRuntime(2561): at java.lang.reflect.Method.invoke(Method.java:511)
06-01 19:05:28.538: E/AndroidRuntime(2561): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
06-01 19:05:28.538: E/AndroidRuntime(2561): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
06-01 19:05:28.538: E/AndroidRuntime(2561): at dalvik.system.NativeStart.main(Native Method)
06-01 19:05:28.538: E/AndroidRuntime(2561): Caused by: java.lang.NullPointerException
06-01 19:05:28.538: E/AndroidRuntime(2561): at com.example.polidoesnttwantacracker.MainActivity.onCreate(MainActivity.java:23)
06-01 19:05:28.538: E/AndroidRuntime(2561): at android.app.Activity.performCreate(Activity.java:5104)
06-01 19:05:28.538: E/AndroidRuntime(2561): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
06-01 19:05:28.538: E/AndroidRuntime(2561): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
06-01 19:05:28.538: E/AndroidRuntime(2561): ... 11 more
My teacher did it the same way I did it and it ran for him :(

Check the identifiers of the views are properly set in activity_main.xml
If you defined those views in the fragment, then check they are in fragment_main.xml and move the declaration you've done in the onCreate of the activity into the onCreateView of the fragment (using rootView to find them)
Check also you are using the proper theme in your application or activity in AndroidManifest.xml
android:theme="#style/Theme.AppCompat.Light"
Cheers

Could not find a method sendMessage(View) in the activity class

MainActivity.java
package com.example.myfirstapp;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.EditText;
import android.content.Intent;
public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
#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;
}
/** Called when the user clicks the Send button */
public void sendMessage(View view) {
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
}
activitymain.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="horizontal" >
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
android:onClick="sendMessage" />
</LinearLayout>
DisplayMessageActivity.java
import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class DisplayMessageActivity extends ActionBarActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get the message from the intent
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Create the text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
// Set the text view as the activity layout
setContentView(textView);
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_display_message,
container, false);
return rootView;
}
}
}
Error Log
04-10 01:37:00.460: W/dalvikvm(1650): threadid=1: thread exiting with uncaught exception (group=0xb3aaeba8)
04-10 01:37:00.520: E/AndroidRuntime(1650): FATAL EXCEPTION: main
04-10 01:37:00.520: E/AndroidRuntime(1650): Process: com.example.myfirstapp, PID: 1650
04-10 01:37:00.520: E/AndroidRuntime(1650): java.lang.IllegalStateException: Could not find a method sendMessage(View) in the activity class com.example.myfirstapp.MainActivity for onClick handler on view class android.widget.Button
04-10 01:37:00.520: E/AndroidRuntime(1650): at android.view.View$1.onClick(View.java:3810)
04-10 01:37:00.520: E/AndroidRuntime(1650): at android.view.View.performClick(View.java:4438)
04-10 01:37:00.520: E/AndroidRuntime(1650): at android.view.View$PerformClick.run(View.java:18422)
04-10 01:37:00.520: E/AndroidRuntime(1650): at android.os.Handler.handleCallback(Handler.java:733)
04-10 01:37:00.520: E/AndroidRuntime(1650): at android.os.Handler.dispatchMessage(Handler.java:95)
04-10 01:37:00.520: E/AndroidRuntime(1650): at android.os.Looper.loop(Looper.java:136)
04-10 01:37:00.520: E/AndroidRuntime(1650): at android.app.ActivityThread.main(ActivityThread.java:5017)
04-10 01:37:00.520: E/AndroidRuntime(1650): at java.lang.reflect.Method.invokeNative(Native Method)
04-10 01:37:00.520: E/AndroidRuntime(1650): at java.lang.reflect.Method.invoke(Method.java:515)
04-10 01:37:00.520: E/AndroidRuntime(1650): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-10 01:37:00.520: E/AndroidRuntime(1650): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-10 01:37:00.520: E/AndroidRuntime(1650): at dalvik.system.NativeStart.main(Native Method)
04-10 01:37:00.520: E/AndroidRuntime(1650): Caused by: java.lang.NoSuchMethodException: sendMessage [class android.view.View]
04-10 01:37:00.520: E/AndroidRuntime(1650): at java.lang.Class.getConstructorOrMethod(Class.java:472)
04-10 01:37:00.520: E/AndroidRuntime(1650): at java.lang.Class.getMethod(Class.java:857)
04-10 01:37:00.520: E/AndroidRuntime(1650): at android.view.View$1.onClick(View.java:3803)
04-10 01:37:00.520: E/AndroidRuntime(1650): ... 11 more
04-10 01:37:04.820: I/Process(1650): Sending signal. PID: 1650 SIG: 9
I've tried to look at other questions answered similar to mine, but I can't find an answer that seems to help my situation. Can anyone help?

I was struggling with a similar error following the android tutorial
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.myfirstapp, PID: 18300
java.lang.IllegalStateException: Could not find method sendMessage (MainActivity)(View) in a parent or ancestor Context for android:onClick attribute defined on view class android.support.v7.widget.AppCompatButton with id 'button'
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:327)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:284)
at android.view.View.performClick(View.java:5197)
at android.view.View$PerformClick.run(View.java:20909)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5944)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
but in my case the WYSIWYG editor (IntelliJ w/Android Studio plugin) ended up populating the onClick property in activity_main.xml with some extra junk about MainActivity:
android:onClick="sendMessage (MainActivity)"
So I deleted " (MainActivity)" and it stopped crashing. I see this is different from your problem as your xml file already seems correct with android:onClick="sendMessage". But wanted to add it here for any others struggling with what I saw. This was the closest post to the issue I was seeing. I'm just getting started and this was killing me, so hope it helps someone else.

The problem is the onClick property in one of your Button tags:
android:onClick="sendMessage" />
Just make sure you have a method sendMessage(View) in your Activity.

It is because you need to implement implements android.view.View.OnClickListener in your class, therefore add the correct imports i.e. import android.view.View.

Unfortunately app has stopped working

I am new to android application development. I was doing this tutorial app.It's a very simple one. It adds one and subtracts one from the counter.When I run it in the emulator ,it says "Unfortunately tutorial has stopped working." There are no errors in the code. The API level is 17. Please help me out.
Code for java:
public class Startingpoint extends Activity {
int counter=0;
Button add,subtract;
TextView display;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.startingpoint);
add = (Button) findViewById(R.id.bAdd);
subtract= (Button) findViewById(R.id.bSubtract);
display= (Button) findViewById(R.id.text);
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
counter++;
display.setText("The total is " + counter);
}
});
subtract.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
counter--;
display.setText("The total is " + counter);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.startingpoint, menu);
return true;
}
}
Layout code in xml :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView android:id="#+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Your total is 0"
android:textSize="35dp"
android:layout_gravity="center"
android:gravity="center"/>
<Button android:layout_width="250dp"
android:layout_height="wrap_content"
android:text="Add One"
android:layout_gravity="center"
android:textSize="25dp"
android:id="#+id/bAdd"/>
<Button android:layout_width="250dp"
android:layout_height="wrap_content"
android:text="Subtract One"
android:layout_gravity="center"
android:textSize="25dp"
android:id="#+id/bSubtract"/>
</LinearLayout>
Here is the logcat :
03-02 02:45:10.730: D/AndroidRuntime(780): Shutting down VM
03-02 02:45:10.730: W/dalvikvm(780): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
03-02 02:45:10.750: E/AndroidRuntime(780): FATAL EXCEPTION: main
03-02 02:45:10.750: E/AndroidRuntime(780): java.lang.RuntimeException: Unable to start activity ComponentInfo{tutorial.example.tutorial/tutorial.example.tutorial.Startingpoint}: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.access$600(ActivityThread.java:141)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.os.Handler.dispatchMessage(Handler.java:99)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.os.Looper.loop(Looper.java:137)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.main(ActivityThread.java:5041)
03-02 02:45:10.750: E/AndroidRuntime(780): at java.lang.reflect.Method.invokeNative(Native Method)
03-02 02:45:10.750: E/AndroidRuntime(780): at java.lang.reflect.Method.invoke(Method.java:511)
03-02 02:45:10.750: E/AndroidRuntime(780): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-02 02:45:10.750: E/AndroidRuntime(780): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-02 02:45:10.750: E/AndroidRuntime(780): at dalvik.system.NativeStart.main(Native Method)
03-02 02:45:10.750: E/AndroidRuntime(780): Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button
03-02 02:45:10.750: E/AndroidRuntime(780): at tutorial.example.tutorial.Startingpoint.onCreate(Startingpoint.java:22)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.Activity.performCreate(Activity.java:5104)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
03-02 02:45:10.750: E/AndroidRuntime(780): ... 11 more

display= (Button) findViewById(R.id.text);
should be
display= (TextView) findViewById(R.id.text);
Since display is supposed to reference a TextView instance, but you're explictly casting into a Button, and these are not compatible types.

As you got the answer from A-C this time, but for next time in android application development a important suggestion:
Always see the logcat for error, and see the "Caused by:" tag, It specifies what was the cause of the problem with sufficient detail, Also see the line no that caused that error.
And try to find what can be wrong with that line of code.
For example: in your logcat it is showing-
Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button
at tutorial.example.tutorial.Startingpoint.onCreate(Startingpoint.java:22)
So you can try to read the log, and you will understand that in your file Startingpoint.java at line 22 which is located in onCreate method the error is android.widget.TextView cannot be cast to android.widget.Button. So you can easily remove your errors without any help.
Hope that helps not only you current problem but prevented your future time and efforts.

Force close error on application when button is pressed

So whenever I click the button on the startup page, it gives me a force close error. Here's the class for the main.xml layout file:
public class ForeverAloneActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btnstrt = (Button) findViewById(R.id.toq1);
btnstrt.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
// TODO Auto-generated method stub
Intent frstq = new Intent(v.getContext(), QuestionOne.class);
startActivityForResult(frstq, 0);
And this is what I believe is producing the error. This class is related to the page that that when pressing the button on the startup page, you are taken to:
#Override
public void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView (R.layout.frstq);
Button startQ2 = (Button) findViewById(R.id.toq2);
startQ2.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
// TODO Auto-generated method stub
Intent toQ2 = new Intent(v.getContext(), QuestionTwo.class);
final EditText number = (EditText) findViewById(R.id.editText1);
final Toast error = Toast.makeText(QuestionOne.this, "Please insert a value", Toast.LENGTH_SHORT);
if (number.getText().toString().equals("")) {error.show();
}else{
startActivityForResult(toQ2, 0);}
That if statement is there as on the next page, there is an EditText box. I tried to make it so that if there is nothing in the EditText box, it displays a toast message saying "Please insert a value". Until an integer is put into the EditText box, then the button will not work.
If someone can help, it will be much appreciated.
Logcat:
04-07 19:33:58.199: W/dalvikvm(362): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
04-07 19:33:58.221: E/AndroidRuntime(362): FATAL EXCEPTION: main
04-07 19:33:58.221: E/AndroidRuntime(362): android.content.ActivityNotFoundException: Unable to find explicit activity class {com.kenning.foreveralone/com.kenning.foreveralone.QuestionOne}; have you declared this activity in your AndroidManifest.xml?
04-07 19:33:58.221: E/AndroidRuntime(362): at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1404)
04-07 19:33:58.221: E/AndroidRuntime(362): at android.app.Instrumentation.execStartActivity(Instrumentation.java:1378)
04-07 19:33:58.221: E/AndroidRuntime(362): at android.app.Activity.startActivityForResult(Activity.java:2817)
04-07 19:33:58.221: E/AndroidRuntime(362): at com.kenning.foreveralone.ForeverAloneActivity$1.onClick(ForeverAloneActivity.java:22)
04-07 19:33:58.221: E/AndroidRuntime(362): at android.view.View.performClick(View.java:2408)
04-07 19:33:58.221: E/AndroidRuntime(362): at android.view.View$PerformClick.run(View.java:8816)
04-07 19:33:58.221: E/AndroidRuntime(362): at android.os.Handler.handleCallback(Handler.java:587)
04-07 19:33:58.221: E/AndroidRuntime(362): at android.os.Handler.dispatchMessage(Handler.java:92)
04-07 19:33:58.221: E/AndroidRuntime(362): at android.os.Looper.loop(Looper.java:123)
04-07 19:33:58.221: E/AndroidRuntime(362): at android.app.ActivityThread.main(ActivityThread.java:4627)
04-07 19:33:58.221: E/AndroidRuntime(362): at java.lang.reflect.Method.invokeNative(Native Method)
04-07 19:33:58.221: E/AndroidRuntime(362): at java.lang.reflect.Method.invoke(Method.java:521)
04-07 19:33:58.221: E/AndroidRuntime(362): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-07 19:33:58.221: E/AndroidRuntime(362): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-07 19:33:58.221: E/AndroidRuntime(362): at dalvik.system.NativeStart.main(Native Method)

are you adding QuestionTwo in manifiest file ?
check your error - have you declared this activity in your AndroidManifest.xml?

Declare your activity in manifeast file. It seems you forgetted that
<activity android:name="QuestionTwo" />
also dont forget to include every activity in your manifeast file

Hey have you added the QuestionTwo class as an activity in menifest file. If after adding the
Intent toQ2 = new Intent(YourCurrentActivity.this,QuestionTwo.class);
then you must have not added the activity in menifest.B'coz it clearly shows in the log that Activity is not found. You have to declare the activity in menifest file.
Hope you'll get run your app.