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My buttons and Views do nothing after inflating the layout they are in so avoid null object error

My Main Activity. This is where all my code is.
package com.abhiandroid.tablayoutexample;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.VideoView;
import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;
import com.google.android.gms.ads.InterstitialAd;
import com.google.android.gms.ads.MobileAds;
public class MainActivity extends AppCompatActivity {
FrameLayout simpleFrameLayout;
TabLayout tabLayout;
ImageButton imageRopo;
Button btn_show;
InterstitialAd interstitialAd;
AdView adView1,adView2;
TextView textView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LayoutInflater layoutInflater= (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View firstfrag =getLayoutInflater().inflate(R.layout.fragment_first,null);
View thirdfrag =getLayoutInflater().inflate(R.layout.fragment_third,null);
btn_show = (Button)thirdfrag.findViewById(R.id.bt_show);
adView1= (AdView)thirdfrag.findViewById(R.id.ad_view);
adView2= (AdView)thirdfrag.findViewById(R.id.ad_view2);
imageRopo = (ImageButton)firstfrag.findViewById(R.id.buttonropo);
textView = (TextView)firstfrag.findViewById(R.id.testview);
imageRopo.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(android.content.Intent.ACTION_VIEW);
intent.setData(Uri.parse("https://www.youtube.com"));
startActivity(intent);
textView.setText("The button works");
}
});
MobileAds.initialize(this, "ca-app-pub-8708219564656739~8048449285");
AdRequest adRequest = new AdRequest.Builder().addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
.addTestDevice("355696115338836").build();
adView1.loadAd(adRequest);
adView2.loadAd(adRequest);
interstitialAd = new InterstitialAd(this);
interstitialAd.setAdUnitId("ca-app-pub-8708219564656739/2401085524");
interstitialAd.loadAd(new AdRequest.Builder().addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
.addTestDevice("355697115338836").build());
btn_show.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
interstitialAd.show();
}
});
// get the reference of FrameLayout and TabLayout
simpleFrameLayout = (FrameLayout) findViewById(R.id.simpleFrameLayout);
tabLayout = (TabLayout) findViewById(R.id.simpleTabLayout);
// Create a new Tab named "First"
TabLayout.Tab firstTab = tabLayout.newTab();
firstTab.setText("Apps"); // set the Text for the first Tab
firstTab.setIcon(R.drawable.app); // set an icon for the
// first tab
tabLayout.addTab(firstTab); // add the tab at in the TabLayout
// Create a new Tab named "Second"
TabLayout.Tab secondTab = tabLayout.newTab();
secondTab.setText("Products"); // set the Text for the second Tab
secondTab.setIcon(R.drawable.company); // set an icon for the second tab
tabLayout.addTab(secondTab); // add the tab in the TabLayout
// Create a new Tab named "Third"
TabLayout.Tab thirdTab = tabLayout.newTab();
thirdTab.setText("Donate"); // set the Text for the first Tab
thirdTab.setIcon(R.drawable.donation); // set an icon for the first tab
tabLayout.addTab(thirdTab); // add the tab at in the TabLayout
// perform setOnTabSelectedListener event on TabLayout
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
// get the current selected tab's position and replace the fragment accordingly
Fragment fragment = null;
switch (tab.getPosition()) {
case 0:
fragment = new FirstFragment();
break;
case 1:
fragment = new SecondFragment();
break;
case 2:
fragment = new ThirdFragment();
break;
}
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.replace(R.id.simpleFrameLayout, fragment);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.commit();
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
}
My activit_main.xml
<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:layout_gravity="center"
android:clickable="true"
android:focusable="true"
android:gravity="center"
android:orientation="vertical"
tools:context=".MainActivity">
<android.support.design.widget.TabLayout
android:id="#+id/simpleTabLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabBackground="#android:color/darker_gray"
app:tabIndicatorColor="#f00"
app:tabSelectedTextColor="#f00"
app:tabTextColor="#000" />
<FrameLayout
android:id="#+id/simpleFrameLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#9C27B0">
</FrameLayout>
</LinearLayout>
The buttons and views are in different fragments hence me having to inflate the layouts they are in.
This is my firstfragment.xml. This is where one of my button and one of my TextView is.
<ScrollView 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:background="#ffeadb"
tools:context=".FirstFragment">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#f7c5a8"
android:orientation="vertical"
tools:context=".FirstFragment"
tools:layout_editor_absoluteY="1dp">
<TextView
android:id="#+id/textView23"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="4dp"
android:fontFamily="#font/roboto_bold"
android:gravity="center"
android:text="Why Choose China when you have the option for Indian?"
android:textSize="37sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="#+id/imageView"
android:layout_width="106dp"
android:layout_height="109dp"
android:layout_marginStart="24dp"
android:layout_marginLeft="24dp"
android:layout_marginTop="208dp"
android:layout_marginEnd="281dp"
android:layout_marginRight="281dp"
android:src="#drawable/tiktokl"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/textView22"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="12dp"
android:layout_marginLeft="12dp"
android:layout_marginTop="148dp"
android:layout_marginEnd="35dp"
android:layout_marginRight="35dp"
android:gravity="center"
android:text="Why Choose Chinese when you can choose an Indian Alternative."
android:textSize="16sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.255"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="#+id/imageView3"
android:layout_width="114dp"
android:layout_height="114dp"
android:layout_marginStart="149dp"
android:layout_marginLeft="149dp"
android:layout_marginTop="192dp"
android:layout_marginEnd="148dp"
android:layout_marginRight="148dp"
android:src="#drawable/red_arrow"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageButton
android:id="#+id/buttonropo"
android:layout_width="132dp"
android:layout_height="118dp"
android:layout_marginStart="281dp"
android:layout_marginLeft="281dp"
android:layout_marginTop="183dp"
android:layout_marginEnd="24dp"
android:layout_marginRight="24dp"
android:layout_marginBottom="5dp"
android:adjustViewBounds="true"
android:background="#android:color/transparent"
android:baselineAlignBottom="false"
android:cropToPadding="true"
android:src="#drawable/roposoapplog"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/testview"
android:layout_width="88dp"
android:layout_height="19dp"
android:layout_marginStart="168dp"
android:layout_marginLeft="168dp"
android:layout_marginTop="336dp"
android:layout_marginEnd="155dp"
android:layout_marginRight="155dp"
android:textSize="25sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
</ScrollView>
My ThirdFragement Activity file is very empty.
package com.abhiandroid.tablayoutexample;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
public class FirstFragment extends Fragment {
public FirstFragment() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_first, container, false);
}
}
Before inflating the layouts, I would get a null object error and after inflating them they no-longer seem to work. They don't do anything. As you can see in my MainActivity.java file I had made is so that when a user clicks a button it redirects them to a website. I even made a TextView that updates itself when the Button is clicked so that I know that the Button is working. I have spent days trying to fix this error and have made no progress. I suspect it is related to some code being wrong while making the fragments.

You should add the logic for your Fragment's views inside your Fragment class.
So, instead of doing the logic for the button in the Activity, do it under the Fragment onCreateView():
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_first, container, false);
imageRopo = (ImageButton) v.findViewById(R.id.buttonropo);
textView = (TextView) v.findViewById(R.id.testview);
imageRopo.setOnClickListener(new View.OnClickListener() { ...
// ... and so on
return v;
}

Switching between fragments in a layout with BottomNavigationView

This is my first attempt to develop an android application.
I have a MainActivity with ConstraintLayout that has BottomNavigationView. Whenever the first navigation item is selected, I want to display a list of category (displayed in a fragment), then whenever this category is selected, another list will be displayed for items related to that particular category (in another fragment).
I have read in (Android - fragment .replace() doesn't replace content - puts it on top) it states that "static fragments written in XML are unable to be replaced, it has to be in a fragment container", how does it look like?
I tried to create my fragment container, but there is something wrong when I try to get the ListView (grand child of the container)
categoriesListView = getView().findViewById(R.id.categoriesList);
returns null.
MainActivity
package com.alsowaygh.getitdone.view.main;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.MenuItem;
import android.widget.TextView;
import com.alsowaygh.getitdone.R;
import com.alsowaygh.getitdone.view.services.CategoriesListFragment;
import com.alsowaygh.getitdone.view.services.OnCategorySelectedListener;
import com.alsowaygh.getitdone.view.services.ServicesListFragment;
public class MainActivity extends AppCompatActivity implements OnCategorySelectedListener {
private static final String TAG = "MainActivity";
FragmentManager fragmentManager;
FragmentTransaction fragmentTransaction;
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_services:
// mTextMessage.setText(R.string.title_services);
CategoriesListFragment categoriesListFragment = new CategoriesListFragment();
fragmentTransaction.add(R.id.container, categoriesListFragment);
fragmentTransaction.commit();
return true;
case R.id.navigation_bookings:
// mTextMessage.setText(R.string.title_bookings);
return true;
case R.id.navigation_chats:
// mTextMessage.setText(R.string.title_chats);
return true;
case R.id.navigation_settings:
return true;
}
return false;
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BottomNavigationView navigation = findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
fragmentManager = getSupportFragmentManager();
fragmentTransaction = fragmentManager.beginTransaction();
}
#Override
public void onCategorySelected(String category) {
Log.w(TAG, "Successfully created CategoryListFragment!");
}
}
activity_main layout
<?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:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".view.main.MainActivity">
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigation"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="0dp"
android:layout_marginStart="0dp"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="#menu/navigation" />
</android.support.constraint.ConstraintLayout>
Fragment
package com.alsowaygh.getitdone.view.services;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import com.alsowaygh.getitdone.R;
import com.alsowaygh.getitdone.view.main.MainActivity;
public class CategoriesListFragment extends Fragment {
private ListView categoriesListView;
OnCategorySelectedListener categoryListener;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
final Bundle savedInstanceState) {
//initializing root view first to refer to it
View rootView = inflater.inflate(R.layout.activity_main, container, false);
//initializing ListView
categoriesListView = getView().findViewById(R.id.categoriesList);
//categories list
final String[] categories = {"first category", "second category", "third category", "Fourth category"};
//initializing and adding categories strings to the addapter
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(this.getContext(),
R.layout.category_textview);
for (String c : categories) {
arrayAdapter.add(c);
}
categoriesListView.setAdapter(arrayAdapter);
//implement onListItemClick
categoriesListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//retrieve string from categories list at clicked position
categoryListener.onCategorySelected(categories[position]);
}
});
return rootView;
}
#Override //to fource container activity to implement the OnCategorySelectedListener
public void onAttach(Context context) {
super.onAttach(context);
try{
categoryListener = (OnCategorySelectedListener) context;
}catch(ClassCastException e){
throw new ClassCastException(context.toString() + "must implement OnCategorySelectedListener");
}
}
}
fragments container
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
android:id="#+id/categories_list_fragment"
android:name="com.alsowaygh.getitdone.view.services.CategoriesListFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="8dp"
android:layout_marginTop="8dp">
<ListView
android:id="#+id/categoriesList"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp" />
</fragment>
</FrameLayout>
Your help will be much appreciated.

You need to add the FrameLayout container within the layout file of the MainActivity(activity_main), onclick of the buttons in BottomNavigationView replace with the fragment. In this way you have a Activity and the fragments are shown within the activity, on click of each menu item you can invoke to replace it with the fragments.
This should resolve your problem.
You need to change the layout as below in activity_main.xml.
<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:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".view.main.MainActivity">
<FrameLayout
android:id="#+id/frame"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginEnd="0dp"
android:layout_marginStart="0dp"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="#menu/navigation" />
</android.support.constraint.ConstraintLayout>
In the MainActivity code, you need to change as below:
case R.id.navigation_services:
// mTextMessage.setText(R.string.title_services);
CategoriesListFragment categoriesListFragment = new CategoriesListFragment();
fragmentTransaction.replace(R.id.frame, categoriesListFragment);
fragmentTransaction.commit();
return true;
In the fragment layout file change to LinearLayout:
<LinearLayout
android:id="#+id/categories_list_fragment"
android:name="com.alsowaygh.getitdone.view.services.CategoriesListFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="8dp"
android:layout_marginTop="8dp">
<ListView
android:id="#+id/categoriesList"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp" />
</LinearLayout>
EDIT
In the fragment code, change the layout to the name of the fragment layout file(R.layout.fragment_layout_name).
View rootView = inflater.inflate(R.layout.fragment_layout_name, container, false);
//initializing ListView
categoriesListView = rootView.findViewById(R.id.categoriesList);

Unfortunately app stopped work

As I press the "Start Activity" button in my app it won't working and forced to stop its working.
Here is 1st xml file (get.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" >
<TextView
android:id="#+id/etget"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="Enter Your Gender" />
<Button
android:id="#+id/bget1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_below="#id/etget"
android:text="Start Activity" />
<Button
android:id="#+id/bget2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#id/etget"
android:layout_toLeftOf="#id/bget1"
android:text="Start Activity for Result " />
<TextView
android:id="#+id/tvget"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#id/bget2"
android:text="TextView" />
</RelativeLayout>
Here is java file, Get.java:
package example.katta;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class Get extends Activity implements OnClickListener {
Button bg1, bg2;
TextView tv;
TextView etg;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.get);
etg = (TextView) findViewById(R.id.etget);
bg1 = (Button) findViewById(R.id.bget1);
bg2 = (Button) findViewById(R.id.bget2);
tv = (TextView) findViewById(R.id.tvget);
bg1.setOnClickListener(this);
bg2.setOnClickListener(this);
}
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
switch (arg0.getId()) {
case R.id.bget1:
String bread = etg.getText().toString();
Bundle basket = new Bundle();
basket.putString("key", bread);
Intent a = new Intent(Get.this, Send.class);
a.putExtras(basket);
startActivity(a);
break;
case R.id.bget2:
break;
}
}
}
Here is 2nd xml file(send.xml):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/etsend"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
</TextView>
<RadioGroup
android:id="#+id/rgsend"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<RadioButton
android:id="#+id/rb1send"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Male" />
<RadioButton
android:id="#+id/rb2send"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Female" />
</RadioGroup>
<TextView
android:id="#+id/tvsend"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView" />
<Button
android:id="#+id/buttonsend"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Submit" />
</LinearLayout>
Here is java file(Send.java) :
package example.katta;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;
import android.widget.TextView;
public class Send extends Activity implements OnClickListener, OnCheckedChangeListener {
Button bts;
TextView tvs,ets;
RadioGroup selection;
String gotbread;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.send);
Initialize();
Bundle gotbasket = getIntent().getExtras();
gotbread = gotbasket.getString("key");
tvs.setText(gotbread);
}
private void Initialize() {
// TODO Auto-generated method stub
ets = (TextView) findViewById(R.id.etsend);
bts = (Button) findViewById(R.id.buttonsend);
tvs = (TextView) findViewById(R.id.tvsend);
selection = (RadioGroup) findViewById(R.id.rgsend);
bts.setOnClickListener(this);
selection.setOnCheckedChangeListener(this);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
public void onCheckedChanged(RadioGroup arg0, int arg1) {
// TODO Auto-generated method stub
switch (arg1) {
case R.id.rb1send:
break;
case R.id.rb2send:
break;
}
}
}

The error is:
android.content.ActivityNotFoundException: Unable to find explicit activity class {example.katta/example.katta.Send}; have you declared this activity in your AndroidManifest.xml?
The solution is to add Send Activity in your AndroidManifest.xml:
<activity
android:name=".Send" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

You should declarate every activities in your manifest, also I think you can create a better code.
I'll give some recommendations to help you.
1- You can explicit in naming their views.
<TextView
android:id="#+id/txt_view_send"
... >
</TextView>
2- Use camelNotation java code
Bundle gotBasket ...
Future large projects is of great help!
3- Use match_parent un your views
FILL_PARENT (renamed MATCH_PARENT in API Level 8 and higher), which means that the view wants to be as big as its parent.
http://developer.android.com/reference/android/view/ViewGroup.LayoutParams.html
4- Bundle is used only when you have many arguments. You can do something like this in your example.
//you can add a variable to get editText value or pass direct the value in to putExtras()
String bread = etg.getText().toString();
Intent a = new Intent(Get.this, Send.class);
a.putExtras("key", bread);
startActivity(a);
http://developer.android.com/reference/android/content/Intent.html
4-validating can help avoid exceptions.
//example
if(getIntent().getExtras() != null){
tvs.setText(getIntent().getExtras().getString("key"));
}
//your example
Bundle gotbasket = getIntent().getExtras();
if(gotbasket != null){
gotbread = gotbasket.getString("key");
if(gotbread != null{
tvs.setText(gotbread);
}
It can produce NullPointerException.
I hope it helps you!!
Cheers
programming continues!

How to handle retrive a data from two bundle in single form

Hello everyone if you would kindly help me. I'm stuck on how to retrieve the bundle data from another activity. Basically I have two activities which is that when I pressed a button on the first activity, it will go on the second activity and then sets the string values which is later on to be passed on the first activity. What I did was I used the bundle to put the string values. Here i have 3 forms. I am sending bundle values to second from from 1st form and returning bundle values from 3rd from to second from.
My question is that how can I handle the two bundle(activity) in 2nd form.

In first activity on button click you can do :
Intent in = new Intent(activtiy1, secondact.class);
Bundle b = new Bundle();
b.putString("key", "string_to_pass");
.
.
.
in.putextras(b);
startActivity(in);
Now in Second activity you have to get bundle items :
Bundle b=getIntent().getExtras();
String str = b.getString("key");
Hope it helps.

you have first create ui for first activity like this
<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=".FirstActivity" >
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="15dp"
android:layout_marginTop="77dp"
android:text="Button 1" />
<Button
android:id="#+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_marginBottom="110dp"
android:layout_marginLeft="38dp"
android:layout_toRightOf="#+id/button1"
android:text="Button 2" />
</RelativeLayout>
ui of second activity like this
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="second actvity" />
</LinearLayout>
activity first code where i set index with intent for both button click(you also put string double ling and message with intent)
package com.example.teststart;
import android.os.Bundle;
import android.os.Handler;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class FirstActivity extends Activity implements OnClickListener{
Button b1,b2;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_first);
b1=(Button)findViewById(R.id.button1);
b2=(Button)findViewById(R.id.button2);
b1.setOnClickListener(this);
b2.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
int id=v.getId();
switch(id){
case R.id.button1:
Intent i1=new Intent(FirstActivity.this,secondactivity.class);
i1.putExtra("one", 1);
startActivity(i1);
break;
case R.id.button2:
Intent i2=new Intent(FirstActivity.this,secondactivity.class);
i2.putExtra("one", 2);
startActivity(i2);
break;
}
}
}
and second activity i get that integer value to identify which button is clicked and fire operation on that condition
package com.example.teststart;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class secondactivity extends Activity{
TextView tv;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.secondactvity);
tv=(TextView)findViewById(R.id.textView1);
Bundle extras = getIntent().getExtras();
int index = extras.getInt("one");
if(index==1){
tv.setText("nformation-A "+index);
}else if(index==2){
tv.setText("nformation-B "+index);
}
}
}

Button click force closes the activity

My problem is when I click bSA button I encounter error and the activity closes.
java.lang.runtimeexception unable to start activity componentinfo ...
here is my code
Data.java :
package com.example.myapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class Data extends Activity implements View.OnClickListener {
Button start, startFor;
EditText sendET;
TextView gotAnswer;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.get);
initialize();
}
private void initialize() {
start = (Button) findViewById(R.id.bSA);
startFor = (Button) findViewById(R.id.bSAFR);
sendET = (EditText) findViewById(R.id.etSend);
gotAnswer = (TextView) findViewById(R.id.tvGot);
start.setOnClickListener(this);
startFor.setOnClickListener(this);
}
#Override
public void onClick(View view) {
switch (view.getId()){
case R.id.bSA:
String bread = sendET.getText().toString();
Bundle basket = new Bundle();
basket.putString("key", bread);
Intent a = new Intent(getApplicationContext(), OpenedClass.class);
a.putExtras(a);
startActivity(a);
break;
case R.id.bSAFR:
break;
}
}
}
get.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">
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/etSend" android:layout_gravity="center_horizontal"/>
<Button
android:layout_below="#+id/etSend"
android:layout_alignParentRight="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Start Activity"
android:id="#+id/bSA"/>
<Button
android:layout_toLeftOf="#+id/bSA"
android:layout_alignTop="#+id/bSA"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Start Activity for Results"
android:id="#+id/bSAFR"/>
<TextView
android:layout_below="#+id/bSAFR"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
android:id="#+id/tvGot"/>
</RelativeLayout>
=============================================================
OpenedClass.java
package com.example.myapp;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.RadioGroup;
import android.widget.TextView;
public class OpenedClass extends Activity implements View.OnClickListener, RadioGroup.OnCheckedChangeListener {
TextView question, test;
Button returnData;
RadioGroup selectionList;
String gotBread;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.send);
initialize();
Bundle gotBasket = getIntent().getExtras();
gotBread = gotBasket.getString("key");
question.setText(gotBread);
}
private void initialize() {
question = (TextView) findViewById(R.id.tvQuestion);
test = (TextView) findViewById(R.id.tvText);
returnData = (Button) findViewById(R.id.bReturn);
returnData.setOnClickListener(this);
selectionList = (RadioGroup) findViewById(R.id.rgAnswers);
selectionList.setOnCheckedChangeListener(this);
}
#Override
public void onClick(View view) {
}
#Override
public void onCheckedChanged(RadioGroup arg0, int arg1) {
// TODO Auto-generated method stub
switch (arg1) {
case R.id.rCrazy:
break;
case R.id.rFun:
break;
case R.id.rBoth:
break;
}
}
}
send.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:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceSmall"
android:text="Hosein is ..."
android:id="#+id/tvQuestion"/>
<RadioGroup
android:id="#+id/rgAnswers"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Crazy"
android:id="#+id/rCrazy"
/>
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Super Fun"
android:id="#+id/rFun"/>
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Both"
android:id="#+id/rBoth"/>
</RadioGroup>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Return"
android:id="#+id/bReturn"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New Text"
android:id="#+id/tvText"/>
</LinearLayout>

Intent a = new Intent(getApplicationContext(), OpenedClass.class);
a.putExtras(a);
You cannot put a inside itself. This causes infinite recursion and stack overflow.
You probably wanted
a.putExtras(basket);