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How To Change Font Size Based On Spinner Clicked

Before I explain to you, I told you, I've been searching in all of questions in stackoverflow and many webistes, so don't mark it duplicate or any negative acts. I've been stuck here more than 4 days.
I wanna change a font size based on spinner clicked. Every I click dropdown list spinner, it took me to java.lang.NullPointerException. Here you go:
MyAndroidAppActivity
public class MyAndroidAppActivity extends AppCompatActivity {
private Spinner spinner1, spinnerLatin;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// toolbar
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
//this line shows back button
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
//Display data
Spinner spinnerBackgroundChange = (Spinner)findViewById(R.id.spinner1);
ArrayAdapter<CharSequence> spinnerArrayAdapter = ArrayAdapter.createFromResource(this, R.array.country_arrays, android.R.layout.simple_spinner_item);
spinnerArrayAdapter.setDropDownViewResource(R.layout.textview_with_background);
spinnerBackgroundChange.setAdapter(spinnerArrayAdapter);
addListenerOnSpinnerItemSelection();
addListenerOnSpinner2ItemSelection();
}
public void addListenerOnSpinnerItemSelection() {
spinner1 = (Spinner) findViewById(R.id.spinner1);
spinner1.setOnItemSelectedListener(new SelectedListener());
}
public void addListenerOnSpinner2ItemSelection() {
spinnerLatin = (Spinner) findViewById(R.id.spinnerLatin);
spinnerLatin.setOnItemSelectedListener(new SelectedLatin());
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
this.finish();
return true;
}
return super.onOptionsItemSelected(item);
} }
SelectedListener
public class SelectedListener implements OnItemSelectedListener {
public void onItemSelected (AdapterView <?> parent, View view, int pos, long id){
((TextView) view).setTextColor(Color.RED);
switch (pos) {
case 0:
TextView dgs = (TextView) view.findViewById(R.id.sizedoa);
dgs.setTextSize(30);
break;
case 1:
TextView dgf = (TextView) view.findViewById(R.id.fontLatin);
dgf.setTextSize(30);
break;
default:
//Default image
//image.setImageResource(R.drawable.item2);
break;
}
}
#Override
public void onNothingSelected (AdapterView <?> arg0){
// TODO Auto-generated method stub
} }
main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/reldoa"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="3dp"
android:background="#android:color/white"
android:orientation="vertical">
<TextView
android:id="#+id/sizedoa"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:paddingBottom="10dp"
android:paddingLeft="15dp"
android:paddingTop="5dp"
android:text="Ukuran Font"
android:textColor="#222222"
android:textSize="18sp" />
<Spinner
android:id="#+id/spinner1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true" />
</RelativeLayout>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/reldoa"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="3dp"
android:background="#android:color/white"
android:orientation="vertical">
<TextView
android:id="#+id/sizelatin"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:paddingBottom="10dp"
android:paddingLeft="15dp"
android:paddingTop="5dp"
android:text="Jenis Font"
android:textColor="#222222"
android:textSize="18sp" />
<Spinner
android:id="#+id/spinner2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:entries="#array/type_arrays"
android:prompt="#string/type_font"/>
</RelativeLayout>
<!-- Font latin -->
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/relLatin"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="35dp"
android:background="#android:color/white"
android:orientation="vertical">
<TextView
android:id="#+id/fontLatin"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:paddingBottom="15dp"
android:paddingLeft="15dp"
android:paddingTop="15dp"
android:text="Font Latin"
android:textColor="#226169"
android:textSize="20sp" />
</RelativeLayout>
But, the problem lays here:
Error located here
And this is the result of error:
10-05 00:20:08.848 5035-5035/? E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.NullPointerException
at id.or.tauhid.doadandzikir.SelectedListener.onItemSelected(SelectedListener.java:32)
at android.widget.AdapterView.fireOnSelected(AdapterView.java:892)
at android.widget.AdapterView.access$200(AdapterView.java:49)
at android.widget.AdapterView$SelectionNotifier.run(AdapterView.java:860)
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)
Can you help me to fix the problem please? I've been stuck here 4 days.

In your listener, these lines are almost certainly wrong:
TextView dgs = (TextView) view.findViewById(R.id.sizedoa);
TextView dgf = (TextView) view.findViewById(R.id.fontLatin);
The view argument passed to this method is the view inside the spinner that was clicked, which means that calling view.findViewById() will only look inside (a portion of) the spinner itself. Presumably these views are in your Fragment's or Activity's layout, and not inside the spinner.
How you fix this will depend on exactly how your app is wired together, but one potential possibility is to cast the AdapterView's context to Activity and then find the views inside that:
Activity activity = (Activity) parent.getContext();
TextView dgs = activity.findViewById(R.id.sizedoa);

android java Null point exeption at view.setonclicklistener at the secend init why they do not match

I have this problem and it shows me following error
please help me:
I get a NullPointerException in init2(). Apperently sms is null.
I don't understand the problem
Process: com.example.android.projectdestage, PID: 11049
java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.example.android.projectdestage/com.example.android.projectdestage.MainActivity}:
java.lang.NullPointerException: Attempt to invoke virtual method 'void
android.view.View.setOnClickListener(android.view.View$OnClickListener)'
on a null object reference
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2984)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3045)
at android.app.ActivityThread.-wrap14(ActivityThread.java)
at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1642)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6776)
at java.lang.reflect.Method.invoke(Native Method)
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1518)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void
android.view.View.setOnClickListener(android.view.View$OnClickListener)'
on a null object reference
at
com.example.android.projectdestage.MainActivity.init2(MainActivity.java:60)
at
com.example.android.projectdestage.MainActivity.onCreate(MainActivity.java:38)
at android.app.Activity.performCreate(Activity.java:6956)
at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1126)
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2927)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3045) 
at android.app.ActivityThread.-wrap14(ActivityThread.java) 
at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1642) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6776) 
at java.lang.reflect.Method.invoke(Native Method) 
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1518) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)
****this is my main activity****
import android.app.Dialog;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GoogleApiAvailability;
public class MainActivity extends AppCompatActivity
{
private Button sms;
private Button btnMap;
private static final String TAG = "MainActivity";
private static final int ERROR_DIALOG_REQUEST = 9001;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.activity_main);
if(isServicesOK()){
init();
init2();
}
}
private void init(){
Button btnMap = (Button) findViewById(R.id.btnMap);
btnMap.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this, MapActivity.class);
startActivity(intent);
}
});
}
private void init2()
{
Button sms = (Button) findViewById(R.id.sms);
sms.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent message = new Intent(MainActivity.this, MainActivity2.class);
startActivity(message);
}
});
}
public boolean isServicesOK()
{
Log.d(TAG, "isServicesOK: checking google services version");
int available = GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(MainActivity.this);
if(available == ConnectionResult.SUCCESS)
{
// koulchi mli7 map request
Log.d(TAG, "isServicesOK: Google Play Services is working");
return true;
}
else if(GoogleApiAvailability.getInstance().isUserResolvableError(available))
{
//test d erreur
Log.d(TAG, "isServicesOK: an error occured but we can fix it");
Dialog dialog = GoogleApiAvailability.getInstance().getErrorDialog(MainActivity.this, available, ERROR_DIALOG_REQUEST);
dialog.show();
}else
{
Toast.makeText(this, "You can't make map requests", Toast.LENGTH_SHORT).show();
}
return false;
}
}
`**this is my mainactivity xml**`
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.android.projectdestage.MainActivity">
<Button
android:id="#+id/btnMap"
android:layout_width="87dp"
android:layout_height="45dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="244dp"
android:text="#string/map"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.43"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/smsbtn"
android:layout_width="wrap_content"
android:layout_height="43dp"
android:layout_marginBottom="136dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:text="#string/enter_your_message"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.43"
app:layout_constraintStart_toStartOf="parent" />
</android.support.constraint.ConstraintLayout>
**and the main2activity xml**
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical"
tools:context="com.example.android.projectdestage.MainActivity2">
<TextView
android:id="#+id/editText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/enter_your_message"
android:textSize="30sp" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="519dp"
android:orientation="vertical">
<TextView
android:id="#+id/editText2"
android:layout_width="385dp"
android:layout_height="410dp"
android:layout_marginTop="50dp"
android:layout_weight="1"
android:text="#string/textview" />
<Button
android:id="#+id/btnSendSMSendSms"
android:layout_width="wrap_content"
android:layout_height="250dp"
android:layout_marginLeft="150dp"
android:layout_marginStart="150dp"
android:layout_marginVertical="110dp"
android:layout_weight="1"
android:text="#string/sendsms"
tools:targetApi="o" />
</LinearLayout>
</LinearLayout>
and the the mapactivity xml
i think the main problem is here
<?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">
<fragment 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:id="#+id/map"
tools:context=".MapsActivity"
android:name="com.google.android.gms.maps.SupportMapFragment" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_marginTop="10dp"
android:layout_marginRight="10dp"
android:layout_marginLeft="10dp"
android:elevation="10dp"
android:background="#drawable/white_border"
android:id="#+id/relLayout1" tools:targetApi="lollipop">
<ImageView
android:layout_width="15dp"
android:layout_height="15dp"
android:id="#+id/ic_magnify"
android:layout_centerVertical="true"
android:layout_marginLeft="10dp"
android:src="#drawable/ic_magnify" android:contentDescription="#string/todoo" android:layout_marginStart="10dp" />
<AutoCompleteTextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_toRightOf="#+id/ic_magnify"
android:layout_centerVertical="true"
android:textSize="15sp"
android:textColor="#000"
android:id="#+id/input_search"
android:background="#null"
android:hint="#string/enter_address_city_or_zip_code"
android:imeOptions="actionSearch" android:layout_toEndOf="#+id/ic_magnify" />
</RelativeLayout>
<ImageView
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_below="#id/relLayout1"
android:layout_alignParentRight="true"
android:layout_marginRight="10dp"
android:layout_marginTop="10dp"
android:scaleType="centerCrop"
android:id="#+id/ic_gps"
android:src="#drawable/ic_gps" android:contentDescription="#string/todo" android:layout_alignParentEnd="true" android:layout_marginEnd="10dp" />
<ImageView
android:layout_width="40dp"
android:layout_height="40dp"
android:id="#+id/place_picker"
android:layout_marginLeft="10dp"
android:layout_marginTop="15dp"
android:scaleType="centerCrop"
android:layout_below="#+id/relLayout1"
android:src="#drawable/ic_map" android:contentDescription="#string/todoml" android:layout_marginStart="10dp" />
<ImageView
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_below="#+id/place_picker"
android:layout_marginLeft="10dp"
android:layout_marginTop="15dp"
android:scaleType="centerCrop"
android:id="#+id/place_info"
android:src="#drawable/ic_info" android:layout_marginStart="10dp" android:contentDescription="#string/todoop" />
</RelativeLayout>
thank you
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Button sms = (Button) findViewById(R.id.sms); returns null
This means he can not find R.id.sms in your activity_main.xml layout.
Maybe a typo or copy paste error? Check if this button's ID in this file really is sms.
Also if you have multiple layouts for different screen sizes, etc. Check all of them.

You have smsBtn as an id for sms Button in your activity_main.xml, whereas you've passed sms as id. So id with sms is not found and so button is null and throws null pointer exception.
There is better approach that can accomplish this using Butterknife library:
public class MainActivity extends AppCompatActivity
{
#BindView(R.id.smsBtn)
private Button sms;
#BindView(R.id.btnMap)
private Button btnMap;
private static final String TAG = "MainActivity";
private static final int ERROR_DIALOG_REQUEST = 9001;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.activity_main);
ButterKnife.bind(this);
}
#OnClick({R.id.btnMap, R.id.smsBtn})
public void onClick(View view) {
switch (view.getId()) {
case R.id.btnMap:
//Your functionality
break;
case R.id.smsBtn:
//Your functionality
break;
}
}
}
//Dependency for ButterKnife library
implementation 'com.jakewharton:butterknife:8.8.1'
annotationProcessor 'com.jakewharton:butterknife-compiler:8.8.1'
//Butterknife link
https://github.com/JakeWharton/butterknife

BaseAdapter app crashes [closed]

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 8 years ago.
Improve this question
My app build, but it crashes, and I don't know why.
Basically I'm implementing BaseAdapter inside MainActivity, later I will put it in another class
Here's MainActivity.java
public class MainActivity extends Activity {
ListView mListView;
String[] mTitle={"item1","item2"};
String[] mDetail={"info1","info2"};
int[] mImage ={R.drawable.ic_launcher,R.drawable.ic_launcher};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mListView=(ListView)findViewById(R.id.list);
mListView.setAdapter(new dataListAdapter(mTitle, mDetail, mImage, this));
}
class dataListAdapter extends BaseAdapter {
String[] Title, Detail;
int[] imge;
dataListAdapter() {
Title = null;
Detail = null;
imge=null;
context = null;
}
public dataListAdapter(String[] text, String[] text1,int[] text3, Context ctx) {
Title = text;
Detail = text1;
imge = text3;
context = ctx;
}
public final Context context;
public dataListAdapter(Context mContext){
this.context = mContext;
}
public int getCount() {
// TODO Auto-generated method stub
return Title.length;
}
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return null;
}
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
TextView titleView, detailView;
ImageView imageView;
if(convertView == null){
convertView = LayoutInflater.from(context).inflate(R.layout.custom, parent,false);
titleView = (TextView) convertView.findViewById(R.id.title);
detailView = (TextView) convertView.findViewById(R.id.detail);
imageView = (ImageView) convertView.findViewById(R.id.image);
convertView.setTag(R.id.title, titleView);
convertView.setTag(R.id.detail, detailView);
convertView.setTag(R.id.image, imageView);
}else{
titleView = (TextView) convertView.getTag(R.id.title);
detailView = (TextView) convertView.getTag(R.id.detail);
imageView = (ImageView) convertView.getTag(R.id.image);
}
titleView.setText(Title[position]);
detailView.setText(Detail[position]);
imageView.setImageDrawable(context.getResources().getDrawable(imge[position]));
return convertView;
}
}
Logcat:
01-10 21:20:43.290 26874-26874/com.robigroza.justlisttest E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at com.robigroza.justlisttest.MainActivity$dataListAdapter.getView(MainActivity.java:91)
at android.widget.AbsListView.obtainView(AbsListView.java:2465)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1250)
at android.widget.ListView.onMeasure(ListView.java:1162)
at android.view.View.measure(View.java:15371)
at android.widget.RelativeLayout.measureChild(RelativeLayout.java:602)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:415)
at android.view.View.measure(View.java:15371)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4876)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:15371)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4876)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1396)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
at android.view.View.measure(View.java:15371)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4876)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2423)
at android.view.View.measure(View.java:15371)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2011)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1250)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1425)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1143)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4674)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
at android.view.Choreographer.doCallbacks(Choreographer.java:555)
at android.view.Choreographer.doFrame(Choreographer.java:525)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4960)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
at dalvik.system.NativeStart.main(Native Method)
Here's the custom.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<LinearLayout
android:layout_width="255dp"
android:layout_height="wrap_content"
android:orientation="vertical" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="#+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Video1"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="#339966"
android:textStyle="bold" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="#+id/detail"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="video1"
android:textColor="#606060" />
</LinearLayout>
</LinearLayout>
<ImageView
android:id="#+id/img"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/ic_launcher" />
</LinearLayout>
Here's the main.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: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=".MainActivity">
<ListView
android:id="#+id/list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true" >
</ListView>

Your custom.xml should contain 2 TextViews (title and detail) and an ImageView (image).
E.g. something like this:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/title"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<TextView
android:id="#+id/detail"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<ImageView
android:id="#+id/image"
android:layout_width="50dp"
android:layout_height="50dp"/>
</LinearLayout>

Try this.
Imagview.setImageResource (img [position]);

GridView.FATAL EXCEPTION: main android.content.res.Resources$NotFoundException: String resource ID #0x0

I want that when I click on an element of GridView displayed letter, which I clicked. But initially I got here error when I wanted to take the position of the element. If I understood correctly, gridview does not see the textview, but i don't know why.
Error:
5312-5312/standandroid.ru.words E/AndroidRuntime﹕ FATAL EXCEPTION: main
android.content.res.Resources$NotFoundException: String resource ID #0x0
at android.content.res.Resources.getText(Resources.java:240)
at android.content.res.MiuiResources.getText(MiuiResources.java:131)
at android.widget.Toast.makeText(Toast.java:273)
at standandroid.ru.words.MainActivity$1$1.onItemClick(MainActivity.java:70)
at android.widget.AdapterView.performItemClick(AdapterView.java:298)
at android.widget.AbsListView.performItemClick(AbsListView.java:1130)
at android.widget.AbsListView$PerformClick.run(AbsListView.java:2818)
at android.widget.AbsListView$1.run(AbsListView.java:3498)
at android.os.Handler.handleCallback(Handler.java:730)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5137)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:756)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:572)
at miui.dexspy.DexspyInstaller.main(DexspyInstaller.java:171)
at dalvik.system.NativeStart.main(Native Method)
MainActivity.java :
public class MainActivity extends Activity {
TextView txt, textTV;
EditText etxt;
Button btn;
ArrayAdapter<String> adapter;
GridView gridView;
String name;
char c;
ArrayList arrayList=new ArrayList();
int i;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
txt = (TextView) findViewById(R.id.textView);
etxt = (EditText) findViewById(R.id.editText);
btn = (Button) findViewById(R.id.button);
textTV = (TextView) findViewById(R.id.tv);
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
name = etxt.getText().toString();
TreeSet list = new TreeSet();
for (i = 0; i < name.length(); i++) {
c = name.charAt(i);
list.add(c);
}
arrayList = new ArrayList(list);
adapter = new ArrayAdapter<String>(MainActivity.this, R.layout.item, R.id.tv, arrayList);
gridView = (GridView) findViewById(R.id.gridmain);
gridView.setAdapter(adapter);
ViewGrid();
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(MainActivity.this, position,Toast.LENGTH_LONG).show();
}
});
}
});}
private void ViewGrid(){
gridView.setNumColumns(4);
gridView.setStretchMode(GridView.STRETCH_COLUMN_WIDTH); }}
activity_main.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: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=".MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:id="#+id/textView"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="175dp" />
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/editText"
android:singleLine="true"
android:layout_alignParentTop="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_marginTop="48dp" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New Button"
android:id="#+id/button"
android:layout_below="#+id/editText"
android:layout_centerHorizontal="true"
android:layout_marginTop="44dp" />
<GridView
android:id="#+id/gridmain"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="44dp"
android:layout_alignTop="#+id/textView"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"></GridView>
</RelativeLayout>
item.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/tv"
android:textSize="40sp"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
http://i.stack.imgur.com/j5S93.png

Ohh! I see, the issue is that Toast is thinking of position as a resourceID. If you see Toast specs here, you would see that you can define resourceId or a CharSequence. So make sure you are passing the position as a String. Something like:
Toast.makeText(MainActivity.this, String.valueOf(position),Toast.LENGTH_LONG).show();

Android application crashes every time on startup

I started coding my first app in Android Studio, what it should do at this stage is that you click a button with the digit and it outputs it into the textfield. When i run this code the application crashes right on startup and I have no idea what's wrong.
MyActivity.java
package com.example.david.calculator;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import org.w3c.dom.Text;
public class MyActivity extends Activity {
EditText results;
private int number;
final EditText result = (EditText) findViewById(R.id.number);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
Button one = (Button) findViewById(R.id.button);
one.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
BtnPressed(1);
}
});
}
private void BtnPressed(int i) {
result.setText(Integer.toString(i));
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.my, 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);
}
}
activity_my.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: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=".MyActivity">
<EditText
android:layout_width="fill_parent"
android:layout_height="50dp"
android:id="#+id/number"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:hint="0"
android:background="#ffe7e7e7"
android:textSize="30sp"
android:gravity="center_vertical|right"
android:paddingRight="20dp"
android:editable="true"
android:enabled="true"
android:numeric="integer|signed|decimal" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="1"
android:id="#+id/button"
android:layout_below="#+id/number"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_marginTop="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="2"
android:id="#+id/button2"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_alignTop="#+id/button"
android:layout_toRightOf="#+id/button"
android:layout_marginLeft="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="3"
android:id="#+id/button3"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_alignTop="#+id/button2"
android:layout_toRightOf="#+id/button2"
android:layout_marginLeft="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="4"
android:id="#+id/button4"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_below="#+id/button"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="5"
android:id="#+id/button5"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_alignTop="#+id/button4"
android:layout_toRightOf="#+id/button4"
android:layout_marginLeft="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="6"
android:id="#+id/button6"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_alignTop="#+id/button5"
android:layout_toRightOf="#+id/button5"
android:layout_marginLeft="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="7"
android:id="#+id/button7"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_below="#+id/button4"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="8"
android:id="#+id/button8"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_alignTop="#+id/button7"
android:layout_toRightOf="#+id/button7"
android:layout_marginLeft="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="9"
android:id="#+id/button9"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_alignTop="#+id/button8"
android:layout_toRightOf="#+id/button8"
android:layout_marginLeft="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="0"
android:id="#+id/button11"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_below="#+id/button7"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="10dp" />
<Button
android:layout_width="160dp"
android:layout_height="75dp"
android:text="="
android:id="#+id/button12"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_alignTop="#+id/button11"
android:layout_toRightOf="#+id/button11"
android:layout_marginLeft="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="+"
android:id="#+id/button13"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_alignTop="#+id/button3"
android:layout_toRightOf="#+id/button3"
android:layout_marginLeft="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="-"
android:id="#+id/button14"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_alignTop="#+id/button6"
android:layout_toRightOf="#+id/button6"
android:layout_marginLeft="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="*"
android:id="#+id/button15"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_alignTop="#+id/button9"
android:layout_toRightOf="#+id/button9"
android:layout_marginLeft="10dp" />
<Button
android:layout_width="75dp"
android:layout_height="75dp"
android:text="/"
android:id="#+id/button16"
android:textSize="50sp"
android:background="#ff0fdf22"
android:layout_alignTop="#+id/button12"
android:layout_toRightOf="#+id/button12"
android:layout_marginLeft="10dp" />
Logcat:
07-24 16:30:07.894 26564-26564/com.example.david.calculator D/AndroidRuntime﹕ Shutting down VM
07-24 16:30:07.894 26564-26564/com.example.david.calculator W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x4190aba8)
07-24 16:30:07.899 26564-26564/com.example.david.calculator E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.david.calculator, PID: 26564
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.david.calculator/com.example.david.calculator.MyActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
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 android.app.Activity.findViewById(Activity.java:1884)
at com.example.david.calculator.MyActivity.<init>(MyActivity.java:18)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1208)
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2101)
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)
Thank you very much for all the replies.
            

You are setting your EditText in your main class and not in your classes onCreate method. You can't find a view if the activity hasn't been created yet.
public class MyActivity extends Activity {
EditText results;
private int number;
final EditText result = (EditText) findViewById(R.id.number);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
Button one = (Button) findViewById(R.id.button);
one.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
BtnPressed(1);
}
});
}
Should become
public class MyActivity extends Activity {
EditText results;
private int number;
private EditText result;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
result = (EditText) findViewById(R.id.number);
Button one = (Button) findViewById(R.id.button);
one.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
BtnPressed(1);
}
});
}
You were getting a NullPointerException in your log, this should fix it.

You should move
final EditText result = (EditText) findViewById(R.id.number);
inside onCreate(...) after setContentView(..)
Corrected Code
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
EditText result = (EditText) findViewById(R.id.number);
Button one = (Button) findViewById(R.id.button);
one.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
BtnPressed(1);
}
});
}

Check your code:
final EditText result = (EditText) findViewById(R.id.number);
This should come after setContentView() method just like with the button.

You should do this:
final EditText result = (EditText) findViewById(R.id.number);
in your onCreate after the setContentView.