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Null Pointer Exception while setting value of TextView in an Array Adapter class - Android

I'm getting a NullPointerException while trying to start an Activity which contains a ListView .
In the getView method of the adapter class, the exception happens when the setText function of a textView is being called .
The code bellow is my adapter class:
public class QuestionsListAdapter extends ArrayAdapter<Question> {
Context context;
List<Question> questions;
public QuestionsListAdapter(Context context, List<Question> questions){
super(context, R.layout.list_item_question, questions);
this.context = context;
this.questions = questions;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = vi.inflate(R.layout.list_item_question, null);
Question question = questions.get(position);
TextView tv = (TextView) view.findViewById(R.id.question_list_item_string);
Log.i(TableCreator.LOG_TAG, question.toString()); //this works fine and the string is not null .
tv.setText(question.toString()+""); //NULL POINTER EXCEPTION .
return view;
}
}
As you see, I've logged the string in the logcat and it works just fine, but the next line makes the mistake .
And this is the logcat output:
05-27 13:24:02.979 5325-5325/org.kabiri.operationcheklist I/Operation Checklist﹕ |-Question-> id:1 summary:mySummary comment:myComment solution:mySolution ownerList:dummyOwner
05-27 13:24:02.979 5325-5325/org.kabiri.operationcheklist D/AndroidRuntime﹕ Shutting down VM
05-27 13:24:02.979 5325-5325/org.kabiri.operationcheklist W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xb0f5f648)
05-27 13:24:02.979 5325-5325/org.kabiri.operationcheklist E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at org.kabiri.operationchecklist.adapter.QuestionsListAdapter.getView(QuestionsListAdapter.java:43)
at android.widget.AbsListView.obtainView(AbsListView.java:2177)
at android.widget.ListView.makeAndAddView(ListView.java:1840)
at android.widget.ListView.fillDown(ListView.java:675)
at android.widget.ListView.fillFromTop(ListView.java:736)
at android.widget.ListView.layoutChildren(ListView.java:1655)
at android.widget.AbsListView.onLayout(AbsListView.java:2012)
at android.view.View.layout(View.java:14289)
at android.view.ViewGroup.layout(ViewGroup.java:4562)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
at android.view.View.layout(View.java:14289)
at android.view.ViewGroup.layout(ViewGroup.java:4562)
at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
at android.view.View.layout(View.java:14289)
at android.view.ViewGroup.layout(ViewGroup.java:4562)
at android.support.v7.internal.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:502)
at android.view.View.layout(View.java:14289)
at android.view.ViewGroup.layout(ViewGroup.java:4562)
at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
at android.view.View.layout(View.java:14289)
at android.view.ViewGroup.layout(ViewGroup.java:4562)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
at android.view.View.layout(View.java:14289)
at android.view.ViewGroup.layout(ViewGroup.java:4562)
at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
at android.view.View.layout(View.java:14289)
at android.view.ViewGroup.layout(ViewGroup.java:4562)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1976)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1730)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1004)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5481)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
at android.view.Choreographer.doCallbacks(Choreographer.java:562)
at android.view.Choreographer.doFrame(Choreographer.java:532)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
at android.os.Handler.handleCallback(Handler.java:730)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
The logcat shows that the error happens on this line of my adapter class:
tv.setText(question.toString()+"");
I really appreciate your help .

You already know where the problem is!
tv.setText(question.toString()+"");
is causing the NPE that means the TextView tv is null. And that means that the line
TextView tv = (TextView) view.findViewById(R.id.question_list_item_string);
is not able to find the TextView. Check the question_list_item_string id and make sure it matches the id in your list_item_question.xml file

Android NumberPicker NullPointer why?

i am try to implement a numberPicker to select minute values.
But i am getting a NullPointer Exception at this line:
minutePicker = (NumberPicker) findViewById(R.id.minuten_picker);
Following Code:
public class MainActivity extends Activity {
NumberPicker minutePicker;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Auswahl Minuten zum starten / Stoppen aller
minutePicker = new NumberPicker(MainActivity.this);
minutePicker = (NumberPicker) findViewById(R.id.minuten_picker);
minutePicker.setMaxValue(30);
minutePicker.setOnValueChangedListener(new NumberPicker.OnValueChangeListener() {
#Override
public void onValueChange(NumberPicker picker, int oldVal, int newVal) {
abschaltzeit = minutePicker.getValue();
}
});
minutePicker.setValue(0);
minutePicker.setWrapSelectorWheel(false);
}
}
XML:
<NumberPicker
android:id="#+id/minuten_picker"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="6"
android:layout_column="0"
android:paddingLeft="20dp" />
Log:
09-25 11:00:09.749 10687-10687/de.carsten.awesome.app E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: de.carsten.awesome.app, PID: 10687
java.lang.RuntimeException: Unable to start activity ComponentInfo{de.carsten.awesome.app/de.carsten.awesome.app.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at de.carsten.awesome.app.MainActivity.onCreate(MainActivity.java:83)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)

minutePicker = new NumberPicker(MainActivity.this);
minutePicker = (NumberPicker) findViewById(R.id.minuten_picker);
You're creating a NumberPicker programmatically and then overwriting the reference with whatever findViewById() returns. It returns null if your activity_main layout does not contain a minuten_picker.
Choose only the other: either create it prorgrammatically or find it from a view hierarchy you inflated.
If you choose the programmatic way new NumberPicker(), remember to add it to some layout in your activity view hierarchy, e.g. with setContentView()
If you choose the inflation way, make sure you have the view in your XML layout file.
I'm guessing the NPE you're seeing is actually on the following line where you're trying to invoke a method on the minutePicker and it's null.

I apologize.
I moved the Code from the MainActivity in the creating Fragment and it works with rootView.findView.
Sorry but i am new with the Fragement Konzept.
Thanks a lot for your help !

Android Calculator Bug

I coded a calculator for Android, but when I press the "equals" button while the app is running in the emulator, an error comes in the LogCat and the app closes.
Please help me fix the error.
Here's the LogCat Output:
07-25 01:34:13.213: I/Choreographer(1387): Skipped 39 frames! The application may be doing too much work on its main thread.
07-25 01:34:13.473: D/gralloc_goldfish(1387): Emulator without GPU emulation detected.
07-25 01:34:50.653: I/Choreographer(1387): Skipped 36 frames! The application may be doing too much work on its main thread.
07-25 01:34:52.973: D/AndroidRuntime(1387): Shutting down VM
07-25 01:34:52.973: W/dalvikvm(1387): threadid=1: thread exiting with uncaught exception (group=0xb3ab0ba8)
07-25 01:34:53.103: E/AndroidRuntime(1387): FATAL EXCEPTION: main
07-25 01:34:53.103: E/AndroidRuntime(1387): Process: com.example.owncode, PID: 1387
07-25 01:34:53.103: E/AndroidRuntime(1387): java.lang.IllegalStateException: Could not find a method Sum(View) in the activity class com.example.owncode.MainActivity for onClick handler on view class android.widget.Button with id 'button_calculate'
07-25 01:34:53.103: E/AndroidRuntime(1387): at android.view.View$1.onClick(View.java:3810)
07-25 01:34:53.103: E/AndroidRuntime(1387): at android.view.View.performClick(View.java:4438)
07-25 01:34:53.103: E/AndroidRuntime(1387): at android.view.View$PerformClick.run(View.java:18422)
07-25 01:34:53.103: E/AndroidRuntime(1387): at android.os.Handler.handleCallback(Handler.java:733)
07-25 01:34:53.103: E/AndroidRuntime(1387): at android.os.Handler.dispatchMessage(Handler.java:95)
07-25 01:34:53.103: E/AndroidRuntime(1387): at android.os.Looper.loop(Looper.java:136)
07-25 01:34:53.103: E/AndroidRuntime(1387): at android.app.ActivityThread.main(ActivityThread.java:5017)
07-25 01:34:53.103: E/AndroidRuntime(1387): at java.lang.reflect.Method.invokeNative(Native Method)
07-25 01:34:53.103: E/AndroidRuntime(1387): at java.lang.reflect.Method.invoke(Method.java:515)
07-25 01:34:53.103: E/AndroidRuntime(1387): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
07-25 01:34:53.103: E/AndroidRuntime(1387): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
07-25 01:34:53.103: E/AndroidRuntime(1387): at dalvik.system.NativeStart.main(Native Method)
07-25 01:34:53.103: E/AndroidRuntime(1387): Caused by: java.lang.NoSuchMethodException: Sum [class android.view.View]
07-25 01:34:53.103: E/AndroidRuntime(1387): at java.lang.Class.getConstructorOrMethod(Class.java:472)
07-25 01:34:53.103: E/AndroidRuntime(1387): at java.lang.Class.getMethod(Class.java:857)
07-25 01:34:53.103: E/AndroidRuntime(1387): at android.view.View$1.onClick(View.java:3803)
07-25 01:34:53.103: E/AndroidRuntime(1387): ... 11 more
07-25 01:36:28.423: I/Choreographer(1452): Skipped 52 frames! The application may be doing too much work on its main thread.
07-25 01:36:28.753: D/gralloc_goldfish(1452): Emulator without GPU emulation detected.
07-25 01:36:32.873: I/Choreographer(1452): Skipped 39 frames! The application may be doing too much work on its main thread.
07-25 01:36:35.713: W/ResourceType(1452): No package identifier when getting value for resource number 0x00000009
07-25 01:36:35.723: D/AndroidRuntime(1452): Shutting down VM
07-25 01:36:35.723: W/dalvikvm(1452): threadid=1: thread exiting with uncaught exception (group=0xb3ab0ba8)
07-25 01:36:36.103: E/AndroidRuntime(1452): FATAL EXCEPTION: main
07-25 01:36:36.103: E/AndroidRuntime(1452): Process: com.example.owncode, PID: 1452
07-25 01:36:36.103: E/AndroidRuntime(1452): java.lang.IllegalStateException: Could not execute method of the activity
07-25 01:36:36.103: E/AndroidRuntime(1452): at android.view.View$1.onClick(View.java:3823)
07-25 01:36:36.103: E/AndroidRuntime(1452): at android.view.View.performClick(View.java:4438)
07-25 01:36:36.103: E/AndroidRuntime(1452): at android.view.View$PerformClick.run(View.java:18422)
07-25 01:36:36.103: E/AndroidRuntime(1452): at android.os.Handler.handleCallback(Handler.java:733)
07-25 01:36:36.103: E/AndroidRuntime(1452): at android.os.Handler.dispatchMessage(Handler.java:95)
07-25 01:36:36.103: E/AndroidRuntime(1452): at android.os.Looper.loop(Looper.java:136)
07-25 01:36:36.103: E/AndroidRuntime(1452): at android.app.ActivityThread.main(ActivityThread.java:5017)
07-25 01:36:36.103: E/AndroidRuntime(1452): at java.lang.reflect.Method.invokeNative(Native Method)
07-25 01:36:36.103: E/AndroidRuntime(1452): at java.lang.reflect.Method.invoke(Method.java:515)
07-25 01:36:36.103: E/AndroidRuntime(1452): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
07-25 01:36:36.103: E/AndroidRuntime(1452): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
07-25 01:36:36.103: E/AndroidRuntime(1452): at dalvik.system.NativeStart.main(Native Method)
07-25 01:36:36.103: E/AndroidRuntime(1452): Caused by: java.lang.reflect.InvocationTargetException
07-25 01:36:36.103: E/AndroidRuntime(1452): at java.lang.reflect.Method.invokeNative(Native Method)
07-25 01:36:36.103: E/AndroidRuntime(1452): at java.lang.reflect.Method.invoke(Method.java:515)
07-25 01:36:36.103: E/AndroidRuntime(1452): at android.view.View$1.onClick(View.java:3818)
07-25 01:36:36.103: E/AndroidRuntime(1452): ... 11 more
07-25 01:36:36.103: E/AndroidRuntime(1452): Caused by: android.content.res.Resources$NotFoundException: String resource ID #0x9
07-25 01:36:36.103: E/AndroidRuntime(1452): at android.content.res.Resources.getText(Resources.java:244)
07-25 01:36:36.103: E/AndroidRuntime(1452): at android.widget.TextView.setText(TextView.java:3888)
07-25 01:36:36.103: E/AndroidRuntime(1452): at com.example.owncode.MainActivity.Sum(MainActivity.java:113)
07-25 01:36:36.103: E/AndroidRuntime(1452): ... 14 more
07-25 01:39:31.103: I/Choreographer(1502): Skipped 47 frames! The application may be doing too much work on its main thread.
07-25 01:39:31.383: D/gralloc_goldfish(1502): Emulator without GPU emulation detected.
07-25 01:39:35.203: I/Choreographer(1502): Skipped 42 frames! The application may be doing too much work on its main thread.
07-25 01:39:38.363: W/ResourceType(1502): No package identifier when getting value for resource number 0x00000009
07-25 01:39:38.423: D/AndroidRuntime(1502): Shutting down VM
07-25 01:39:38.423: W/dalvikvm(1502): threadid=1: thread exiting with uncaught exception (group=0xb3ab0ba8)
07-25 01:39:38.603: E/AndroidRuntime(1502): FATAL EXCEPTION: main
07-25 01:39:38.603: E/AndroidRuntime(1502): Process: com.example.owncode, PID: 1502
07-25 01:39:38.603: E/AndroidRuntime(1502): java.lang.IllegalStateException: Could not execute method of the activity
07-25 01:39:38.603: E/AndroidRuntime(1502): at android.view.View$1.onClick(View.java:3823)
07-25 01:39:38.603: E/AndroidRuntime(1502): at android.view.View.performClick(View.java:4438)
07-25 01:39:38.603: E/AndroidRuntime(1502): at android.view.View$PerformClick.run(View.java:18422)
07-25 01:39:38.603: E/AndroidRuntime(1502): at android.os.Handler.handleCallback(Handler.java:733)
07-25 01:39:38.603: E/AndroidRuntime(1502): at android.os.Handler.dispatchMessage(Handler.java:95)
07-25 01:39:38.603: E/AndroidRuntime(1502): at android.os.Looper.loop(Looper.java:136)
07-25 01:39:38.603: E/AndroidRuntime(1502): at android.app.ActivityThread.main(ActivityThread.java:5017)
07-25 01:39:38.603: E/AndroidRuntime(1502): at java.lang.reflect.Method.invokeNative(Native Method)
07-25 01:39:38.603: E/AndroidRuntime(1502): at java.lang.reflect.Method.invoke(Method.java:515)
07-25 01:39:38.603: E/AndroidRuntime(1502): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
07-25 01:39:38.603: E/AndroidRuntime(1502): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
07-25 01:39:38.603: E/AndroidRuntime(1502): at dalvik.system.NativeStart.main(Native Method)
07-25 01:39:38.603: E/AndroidRuntime(1502): Caused by: java.lang.reflect.InvocationTargetException
07-25 01:39:38.603: E/AndroidRuntime(1502): at java.lang.reflect.Method.invokeNative(Native Method)
07-25 01:39:38.603: E/AndroidRuntime(1502): at java.lang.reflect.Method.invoke(Method.java:515)
07-25 01:39:38.603: E/AndroidRuntime(1502): at android.view.View$1.onClick(View.java:3818)
07-25 01:39:38.603: E/AndroidRuntime(1502): ... 11 more
07-25 01:39:38.603: E/AndroidRuntime(1502): Caused by: android.content.res.Resources$NotFoundException: String resource ID #0x9
07-25 01:39:38.603: E/AndroidRuntime(1502): at android.content.res.Resources.getText(Resources.java:244)
07-25 01:39:38.603: E/AndroidRuntime(1502): at android.widget.TextView.setText(TextView.java:3888)
07-25 01:39:38.603: E/AndroidRuntime(1502): at com.example.owncode.MainActivity.Sum(MainActivity.java:113)
07-25 01:39:38.603: E/AndroidRuntime(1502): ... 14 more
Here's my MainActivity.JAVA:
package com.example.owncode;
import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
public class MainActivity extends Activity {
EditText calculatorText;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
calculatorText = (EditText) findViewById(R.id.calculatorText);
}
#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_activity_actions, menu);
return super.onCreateOptionsMenu(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.button_quitProgram) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void button_one_click(View view){
calculatorText.append("1");
}
public void button_two_click(View view){
calculatorText.append("2");
}
public void button_three_click(View view){
calculatorText.append("3");
}
public void button_four_click(View view){
calculatorText.append("4");
}
public void button_five_click(View view){
calculatorText.append("5");
}
public void button_six_click(View view){
calculatorText.append("6");
}
public void button_seven_click(View view){
calculatorText.append("7");
}
public void button_eight_click(View view){
calculatorText.append("8");
}
public void button_nine_click(View view){
calculatorText.append("9");
}
public void button_zero_click(View view){
calculatorText.append("0");
}
public void button_plus_click(View view){
calculatorText.append("+");
}
public void button_minus_click(View view){
calculatorText.append("-");
}
public void button_backspace_click(View view){
if (calculatorText.length()>0){
String calculatorText_text = calculatorText.getText().toString();
calculatorText_text = calculatorText_text.substring(0, calculatorText_text.length()-1);
calculatorText.setText(calculatorText_text);
}
}
public void Sum(View view){
String str = calculatorText.getText().toString();
int len = str.length();
int i=0;
String str1 = "", str2 = "";
char op;
int num1 = 0, num2 = 0, res=0;
for(i=0; i<len; i++){
if(str.charAt(i)=='+' || str.charAt(i)=='-')
break;
str1 = str1 + str.charAt(i);
}
op = str.charAt(i);
i++;
while(i<len){
str2 = str2 + str.charAt(i);
i++;
}
num1 = Integer.parseInt(str1);
num2 = Integer.parseInt(str2);
if(op=='+')
res = num1+num2;
else if(op=='-')
res = num1-num2;
calculatorText.setText(res);
}
}
And, here's my main_activity.xml:
<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:orientation="horizontal" >
<Button
android:id="#+id/button_plus"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/button_minus"
android:layout_alignBottom="#+id/button_minus"
android:layout_alignParentLeft="true"
android:hint="#string/button_plus"
android:onClick="button_plus_click" />
<Button
android:id="#+id/button_zero"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/button_plus"
android:layout_alignBottom="#+id/button_plus"
android:layout_toRightOf="#+id/button_plus"
android:hint="#string/button_zero"
android:onClick="button_zero_click" />
<Button
android:id="#+id/button_minus"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="135dp"
android:hint="#string/button_minus"
android:onClick="button_minus_click" />
<Button
android:id="#+id/button_nine"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/button_minus"
android:layout_alignLeft="#+id/button_minus"
android:hint="#string/button_nine"
android:onClick="button_nine_click" />
<Button
android:id="#+id/button_eight"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/button_zero"
android:layout_toLeftOf="#+id/button_minus"
android:hint="#string/button_eight"
android:onClick="button_eight_click" />
<Button
android:id="#+id/button_seven"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/button_eight"
android:layout_alignBottom="#+id/button_eight"
android:layout_toLeftOf="#+id/button_eight"
android:hint="#string/button_seven"
android:onClick="button_seven_click" />
<Button
android:id="#+id/button_six"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/button_nine"
android:layout_toRightOf="#+id/button_eight"
android:hint="#string/button_six"
android:onClick="button_six_click" />
<Button
android:id="#+id/button_five"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/button_six"
android:layout_alignBottom="#+id/button_six"
android:layout_toRightOf="#+id/button_seven"
android:hint="#string/button_five"
android:onClick="button_five_click" />
<Button
android:id="#+id/button_four"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/button_five"
android:layout_alignBottom="#+id/button_five"
android:layout_toLeftOf="#+id/button_five"
android:hint="#string/button_four"
android:onClick="button_four_click" />
<Button
android:id="#+id/button_three"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/button_six"
android:layout_toRightOf="#+id/button_five"
android:hint="#string/button_three"
android:onClick="button_three_click" />
<Button
android:id="#+id/button_two"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/button_three"
android:layout_alignBottom="#+id/button_three"
android:layout_toRightOf="#+id/button_four"
android:hint="#string/button_two"
android:onClick="button_two_click" />
<Button
android:id="#+id/button_one"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/button_two"
android:layout_alignBottom="#+id/button_two"
android:layout_toLeftOf="#+id/button_two"
android:hint="#string/button_one"
android:onClick="button_one_click" />
<Button
android:id="#+id/button_backspace"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/button_three"
android:layout_marginBottom="29dp"
android:layout_marginLeft="17dp"
android:layout_toRightOf="#+id/calculatorText"
android:hint="#string/button_backspace"
android:onClick="button_backspace_click" />
<Button
android:id="#+id/button_calculate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/button_backspace"
android:layout_alignLeft="#+id/button_backspace"
android:hint="#string/button_calculate"
android:onClick="Sum" />
<EditText
android:id="#+id/calculatorText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/button_backspace"
android:layout_alignParentLeft="true"
android:editable="false"
android:ems="10"
android:hint="#string/calculatorText_text" >
<requestFocus />
</EditText>
</RelativeLayout>
I know it's all simple code but this is my first app and please help me so that I can get it running on a few of my relatives' devices.

Because of this line you are getting error
calculatorText.setText(res);
change it into
calculatorText.setText(""+res);
You are setting Integer value..so View taken it as a Resouce ID.

Change calculatorText.setText(res); to calculatorText.setText(Integer.toString(res));
You cannot set an integer value to an EditText.

Android application keep crashing

in the last few days I tried to develop android applications with no success, for some reason my application keep crashing.
the application keeps throwing few exceptions that I didn't succeeded to handle with.
MainActivity.java :
package com.mobIce.digicoin.digitalcoin;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
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.os.Build;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends ActionBarActivity {
private List<Coin> coins;
public MainActivity(){
coins = new ArrayList<Coin>();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
populateCoins();
populateListView();
}
}
private void populateCoins() {
coins.add(new Coin("Bitcoin", "650", "4", "http://coinmarketcap.com/img/Bitcoin.png"));
coins.add(new Coin("Dogecoin", "100", "400", "http://coinmarketcap.com/img/Bitcoin.png"));
coins.add(new Coin("fafaf", "8065", "400", "http://coinmarketcap.com/img/Bitcoin.png"));
}
private void populateListView() {
ArrayAdapter<Coin> adapter = new MyListAdapter();
ListView list = (ListView) findViewById(R.id.coinsListView);
list.setAdapter(adapter);
}
#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;
}
}
private class MyListAdapter extends ArrayAdapter<Coin> {
public MyListAdapter()
{
super(MainActivity.this, R.layout.coin_layout, coins);
}
#Override
public View getView(int position, View convertView, ViewGroup parent){
View itemView = convertView;
if(itemView == null)
itemView = getLayoutInflater().inflate(R.layout.coin_layout, parent, false);
//find the coin to work with.
Coin currentCoin = coins.get(position);
//fill the view
try{
TextView coinName = (TextView) itemView.findViewById(R.id.coinName);
coinName.setText(currentCoin.getName());
TextView coinPrice = (TextView) itemView.findViewById(R.id.coinPrice);
coinPrice.setText(currentCoin.getPrice());
TextView coinPercentage = (TextView) itemView.findViewById(R.id.coinPercentage);
coinPercentage.setText(currentCoin.getPercentage());
}
catch (NullPointerException e){ }
return itemView;
}
}
}
activity_main.xml:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.mobIce.digicoin.digitalcoin.MainActivity"
tools:ignore="MergeRootFrame" />
fragment_main.xml:
<LinearLayout
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
<ListView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/coinsListView"
android:paddingLeft="30dp" />
</LinearLayout>
coin_layout.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"
android:padding="8dp">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="coinName"
android:id="#+id/coinName"
android:layout_alignParentTop="true"
android:layout_toRightOf="#+id/coinIcon"
android:layout_marginTop="35dp"
android:layout_marginLeft="20dp" />
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/coinIcon"
android:maxHeight="80dp"
android:maxWidth="80dp"
android:minHeight="80dp"
android:minWidth="80dp"
android:src="#drawable/dogecoin"
android:longClickable="false"
android:focusable="false"
android:focusableInTouchMode="false"
android:baselineAlignBottom="false"
android:clickable="false"
android:adjustViewBounds="true"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Large Text"
android:id="#+id/coinPrice"
android:layout_marginLeft="35dp"
android:layout_alignTop="#+id/coinIcon"
android:layout_toRightOf="#+id/coinName"
android:layout_marginTop="25dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="Medium Text"
android:id="#+id/coinPercentage"
android:layout_below="#+id/coinPrice"
android:layout_alignLeft="#+id/coinPrice"
android:layout_alignStart="#+id/coinPrice" />
</RelativeLayout>
logcat trace:
03-17 08:59:33.977 1107-1107/com.mobIce.digicoin.digitalcoin D/AndroidRuntime﹕ Shutting down VM
03-17 08:59:33.977 1107-1107/com.mobIce.digicoin.digitalcoin W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xb1a38ba8)
03-17 08:59:33.987 1107-1107/com.mobIce.digicoin.digitalcoin E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.mobIce.digicoin.digitalcoin, PID: 1107
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobIce.digicoin.digitalcoin/com.mobIce.digicoin.digitalcoin.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.mobIce.digicoin.digitalcoin.MainActivity.populateListView(MainActivity.java:47)
at com.mobIce.digicoin.digitalcoin.MainActivity.onCreate(MainActivity.java:36)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)
03-17 09:04:09.857 1149-1149/com.mobIce.digicoin.digitalcoin D/AndroidRuntime﹕ Shutting down VM
03-17 09:04:09.857 1149-1149/com.mobIce.digicoin.digitalcoin W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xb1a38ba8)
03-17 09:04:09.867 1149-1149/com.mobIce.digicoin.digitalcoin E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.mobIce.digicoin.digitalcoin, PID: 1149
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobIce.digicoin.digitalcoin/com.mobIce.digicoin.digitalcoin.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.mobIce.digicoin.digitalcoin.MainActivity.populateListView(MainActivity.java:50)
at com.mobIce.digicoin.digitalcoin.MainActivity.onCreate(MainActivity.java:39)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)
03-17 09:06:36.697 1192-1192/com.mobIce.digicoin.digitalcoin D/AndroidRuntime﹕ Shutting down VM
03-17 09:06:36.697 1192-1192/com.mobIce.digicoin.digitalcoin W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xb1a38ba8)
03-17 09:06:36.717 1192-1192/com.mobIce.digicoin.digitalcoin E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.mobIce.digicoin.digitalcoin, PID: 1192
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobIce.digicoin.digitalcoin/com.mobIce.digicoin.digitalcoin.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.mobIce.digicoin.digitalcoin.MainActivity.populateListView(MainActivity.java:50)
at com.mobIce.digicoin.digitalcoin.MainActivity.onCreate(MainActivity.java:39)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)
03-17 09:13:38.647 1239-1239/com.mobIce.digicoin.digitalcoin D/AndroidRuntime﹕ Shutting down VM
03-17 09:13:38.647 1239-1239/com.mobIce.digicoin.digitalcoin W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xb1a38ba8)
03-17 09:13:38.747 1239-1239/com.mobIce.digicoin.digitalcoin E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.mobIce.digicoin.digitalcoin, PID: 1239
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobIce.digicoin.digitalcoin/com.mobIce.digicoin.digitalcoin.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.mobIce.digicoin.digitalcoin.MainActivity.populateListView(MainActivity.java:50)
at com.mobIce.digicoin.digitalcoin.MainActivity.onCreate(MainActivity.java:37)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)
03-17 09:13:45.127 1239-1239/com.mobIce.digicoin.digitalcoin I/Process﹕ Sending signal. PID: 1239 SIG: 9
03-17 09:19:34.847 1285-1285/com.mobIce.digicoin.digitalcoin D/AndroidRuntime﹕ Shutting down VM
03-17 09:19:34.847 1285-1285/com.mobIce.digicoin.digitalcoin W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xb1a38ba8)
03-17 09:19:34.857 1285-1285/com.mobIce.digicoin.digitalcoin E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.mobIce.digicoin.digitalcoin, PID: 1285
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobIce.digicoin.digitalcoin/com.mobIce.digicoin.digitalcoin.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.mobIce.digicoin.digitalcoin.MainActivity.populateListView(MainActivity.java:50)
at com.mobIce.digicoin.digitalcoin.MainActivity.onCreate(MainActivity.java:37)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)
03-17 09:20:11.987 1285-1285/com.mobIce.digicoin.digitalcoin I/Process﹕ Sending signal. PID: 1285 SIG: 9

Your coinsListView is in the fragment layout and not in activity layout. You cannot access it with findViewById() in populateListView() called from activity onCreate(). Instead, move the list view population to the fragment's onCreateView() after the inflation, calling findViewById() on the rootView layout you just inflated.

Calling static method in one Activity from another Activity

I have these methods in X.class:
public void sendMessage(String message) {
// Check that we're actually connected before trying anything
if (mChatService.getState() != BluetoothChatService.STATE_CONNECTED) {
Toast.makeText(this, R.string.not_connected, Toast.LENGTH_SHORT).show();
return;
}
// Check that there's actually something to send
if (message.length() > 0) {
// Get the message bytes and tell the BluetoothChatService to write
byte[] send = message.getBytes();
mChatService.write(send);
// Reset out string buffer to zero and clear the edit text field
mOutStringBuffer.setLength(0);
//mOutEditText.setText(mOutStringBuffer);
}
}
public static void sendMessage1(String message1){
call1.sendMessage(message1);
}
And I have the following toggleSwitch that Im clicking from another acitvity namely Y.class:
tb3.setOnClickListener(new OnClickListener() {
public void onClick(View v){
if (tb3.isChecked()){
String message = "u";
X.sendMessage1(message);
//clearer();
} else if (!tb3.isChecked()){
String message = "y";
//clearer();
}
}
});
Though I'm not getting any errors while coding but when I load the app on Android and then click on this toggleswitch my app dies?
Log:
E/AndroidRuntime( 4866): java.lang.NullPointerException
E/AndroidRuntime( 4866): at com.winacro.andRHOME.andRHOME.sendMessage1(andRHOME.java:282)
E/AndroidRuntime( 4866): at com.winacro.andRHOME.EECA2$1.onClick(EECA2.java:57)
E/AndroidRuntime( 4866): at android.view.View.performClick(View.java:3534)
E/AndroidRuntime( 4866): at android.widget.CompoundButton.performClick(CompoundButton.java:104)
E/AndroidRuntime( 4866): at android.view.View$PerformClick.run(View.java:14263)
E/AndroidRuntime( 4866): at android.os.Handler.handleCallback(Handler.java:605)
E/AndroidRuntime( 4866): at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime( 4866): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime( 4866): at android.app.ActivityThread.main(ActivityThread.java:4441)
E/AndroidRuntime( 4866): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime( 4866): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime( 4866): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
E/AndroidRuntime( 4866): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
E/AndroidRuntime( 4866): at dalvik.system.NativeStart.main(Native Method)
W/ActivityManager( 273): Force finishing activity com.winacro.andRHOME/.EECA2