Button Listener for button in fragment in android

Question

I am new to Android and trying to learn on my own. But I am having a tough time with Fragments. I am creating a simple application to learn fragments. I think it may seem silly but I really can't get this to work.

All I want to do is on the click of a button (buttonSayHi) in Fragment_One, Fragment_One should be replaced by Fragment_Two.

I am not sure when the Fragment code is called and where am I supposed to write my code to call the second fragment. I get the error: Unable to start Activity component.

However, the code works fine if I discard the listener for button and the fragment is displayed within the activity.

I have done considerable research, read the fragments tutorial on developer.android.com and also the tutorial by Lars Vogella. I think my concepts are not clear.

Any help will be appreciated.

The following is the code:

activity_main.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"     android:id="@+id/frameLayoutFragmentContainer"     android:layout_width="fill_parent"     android:layout_height="fill_parent" >  </FrameLayout> 

fragment_one.xml

<?xml version="1.0" encoding="utf-8"?>  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="fill_parent"     android:layout_height="fill_parent"     android:orientation="vertical" >      <EditText         android:id="@+id/editTextPersonName"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:ems="10"         android:inputType="textPersonName" >          <requestFocus />     </EditText>      <Button         android:id="@+id/buttonSayHi"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="Say Hi"          android:onClick="onButtonClicked"/>  </LinearLayout> 

fragment_two.xml

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="fill_parent"     android:layout_height="fill_parent"     android:orientation="vertical" >      <TextView         android:id="@+id/textViewResult"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="I will say Hi!" />  </LinearLayout> 

MainActivity.java

package com.example.fragmenttutorial;  import android.os.Bundle; import android.view.View; import android.widget.Button; import android.app.Activity; import android.app.Fragment; import android.app.FragmentManager; import android.app.FragmentTransaction;  public class MainActivity extends Activity{      View view;     FragmentManager fragmentManager = getFragmentManager();     FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);               Fragment fragmentOne = new FragmentOne();          fragmentTransaction.add(R.id.frameLayoutFragmentContainer, fragmentOne);         fragmentTransaction.addToBackStack(null);          fragmentTransaction.commit();     }      protected void onButtonClicked()     {         if(view.getId() == R.id.buttonSayHi){             Fragment fragmentTwo = new FragmentTwo();              fragmentTransaction.replace(R.id.frameLayoutFragmentContainer, fragmentTwo);             fragmentTransaction.addToBackStack(null);              fragmentTransaction.commit();             }      } } 

FragmentOne.java

package com.example.fragmenttutorial;  import android.app.Fragment; import android.app.FragmentManager; import android.app.FragmentTransaction; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup;  public class FragmentOne extends Fragment{      View view;     FragmentManager fragmentManager = getFragmentManager();     FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();      @Override     public View onCreateView(LayoutInflater inflater, ViewGroup container,             Bundle savedInstanceState) {          View view = inflater.inflate(R.layout.fragment_one, container, false);         return view;     }  //  protected void onButtonClicked() //  { //      if(view.getId() == R.id.buttonSayHi){ //          Fragment fragmentTwo = new FragmentTwo(); // //          fragmentTransaction.replace(R.id.frameLayoutFragmentContainer, fragmentTwo); //          fragmentTransaction.addToBackStack(null); // //          fragmentTransaction.commit();    // //      } // //  } } 

I have commented out the on click code in the fragment. I have also tried implementing the onClickListener in the fragment.

FragmentTwo.java

package com.example.fragmenttutorial;  import android.app.Fragment; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup;  public class FragmentTwo extends Fragment{      @Override     public View onCreateView(LayoutInflater inflater, ViewGroup container,             Bundle savedInstanceState) {          View view = inflater.inflate(R.layout.fragment_two, container, false);         return view;         } } 

EDIT: I have removed the line android:onClick="onButtonClicked" from my code in XML. And edited the following files but it still does not work. Can you guys provide me a working example without the android:onClick="onButtonClicked" line.

MainActivity.java

package com.example.fragmenttutorial;  import android.os.Bundle; import android.view.View; import android.app.Activity; import android.app.Fragment; import android.app.FragmentManager; import android.app.FragmentTransaction;  public class MainActivity extends Activity{      View view;     Fragment fragmentOne;     FragmentManager fragmentManager = getFragmentManager();     FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);               fragmentOne = new FragmentOne();          fragmentTransaction.add(R.id.frameLayoutFragmentContainer, fragmentOne);         fragmentTransaction.addToBackStack(null);          fragmentTransaction.commit();            } } 

FragmentOne.java

package com.example.fragmenttutorial;  import android.app.Fragment; import android.app.FragmentManager; import android.app.FragmentTransaction; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.view.View.OnClickListener; import android.view.ViewGroup; import android.widget.Button;  public class FragmentOne extends Fragment implements OnClickListener{      View view;     Fragment fragmentTwo;     FragmentManager fragmentManager = getFragmentManager();     FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();      @Override     public View onCreateView(LayoutInflater inflater, ViewGroup container,             Bundle savedInstanceState) {          View view = inflater.inflate(R.layout.fragment_one, container, false);         Button buttonSayHi = (Button) view.findViewById(R.id.buttonSayHi);         buttonSayHi.setOnClickListener(this);         return view;     }      @Override     public void onClick(View v) {          fragmentTwo = new FragmentTwo();          fragmentTransaction.replace(R.id.frameLayoutFragmentContainer, fragmentTwo);         fragmentTransaction.addToBackStack(null);          fragmentTransaction.commit();         } } 

Thank you for your valuable suggestions.

Answer 1

Your fragment class should implement OnClickListener

public class SmartTvControllerFragment extends Fragment implements View.OnClickListener 

Then get view, link button and set onClickListener like in example below

 View view;  @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {      view = inflater.inflate(R.layout.smart_tv_controller_fragment, container, false);     upButton = (Button) view.findViewById(R.id.smart_tv_controller_framgment_up_button);     upButton.setOnClickListener(this);     return view;  } 

And then add onClickListener method and do what you want.

@Override public void onClick(View v) {  //do what you want to do when button is clicked     switch (v.getId()) {         case R.id.textView_help:             switchFragment(HelpFragment.TAG);             break;         case R.id.textView_settings:             switchFragment(SettingsFragment.TAG);             break;     } } 

This is my example of code, but I hope you understood