How to use Fragments in Android

android, android-fragments

Solution

Okie... Finally found a solution. Probably, it wasn't much of a change.

Check out the code below...

activity_main.XML

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <fragment
        android:id="@+id/fragment_content_1"
        android:name="com.example.fragmentexample.Fragment_1"
        android:layout_width="0dip"
        android:layout_weight="0.50"
        android:layout_height="fill_parent" >
    </fragment>

    <fragment
        android:id="@+id/fragment_content_2"
        android:name="com.example.fragmentexample.Fragment_2"
        android:layout_width="0dip"
        android:layout_weight="0.50"
        android:layout_height="fill_parent" >

        <!-- Preview: layout=@layout/fragment_basic -->
    </fragment>

</LinearLayout>

The layouts of fragment_fragment_1 and fragment_fragment_2 remain the same.

Fragment_1.Java

public class Fragment_1 extends Fragment{

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            // TODO Auto-generated method stub      

            View view = inflater.inflate(R.layout.fragment_fragment_1, container, false);

            final EditText edtxtPersonName_Fragment = (EditText) view.findViewById(R.id.edtxtPersonName);
            Button btnSayHi_Fragment = (Button) view.findViewById(R.id.btnSayHi);

            btnSayHi_Fragment.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) {
                    // TODO Auto-generated method stub

                    String name = edtxtPersonName_Fragment.getText().toString();

                    FragmentManager fm = getFragmentManager();
                    Fragment_2 f2 = (Fragment_2) fm.findFragmentById(R.id.fragment_content_2);

                    if(f2 != null && f2.isInLayout())
                    {
                        f2.setName(name);
                    }

                    Activity activity = getActivity();

                    if(activity != null)
                    {
                        Toast.makeText(activity, "Say&ing Hi in Progress...", Toast.LENGTH_LONG).show();
                    }
                }
            });

            return view;


        }

    }

Fragment_2.Java

public class Fragment_2 extends Fragment{

    View view;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        // TODO Auto-generated method stub

        view = inflater.inflate(R.layout.fragment_fragment_2, container, false);        
        return view;
    }

    public void setName(String name)
    {
        TextView txtName = (TextView) view.findViewById(R.id.txtViewResult);
        txtName.setText("Hi " + name);
    }

}

Here is the ScreenShot...

Problem

EDIT ::: Please refer to my answer below... Question::: I am very new to using Fragments in Android and I am completely messed up. I am just trying to build a simple sample application that uses Fragments. My scenario is, I have two fragments in my main activity. The first fragment has an edittext and a button. The second fragment has a textview. When I enter a name in the edittext and click on the button, the textview in the second fragment should display the name entered in the edittext of the first fragment. I am using the static assignment of fragments (assigning fragments in XML). Please refer to the XML files and Code below... activity_main.XML ``` <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" > <fragment android:id="@+id/fragment_content_1" android:name="com.example.fragmentexample.fragment_fragment_1" android:layout_width="fill_parent" android:layout_height="fill_parent" > </fragment> <fragment android:id="@+id/fragment_content_2" android:name="com.example.fragmentexample.fragment_fragment_2" android:layout_width="fill_parent" android:layout_height="fill_parent" >  </fragment> </LinearLayout> ``` fragment_fragment_1.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" > <EditText android:id="@+id/edtxtPersonName" android:layout_width="match_parent" android:layout_height="wrap_content" android:ems="10" android:inputType="textPersonName" > <requestFocus /> </EditText> <Button android:id="@+id/btnSayHi" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Say Hi" /> </LinearLayout> ``` fragment_fragment_2.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/txtViewResult" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="I will say Hi" /> </LinearLayout> ``` Java Files ::: MainActivity.Java ``` public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.activity_main, menu); return true; } } ``` Fragment_1.Java ``` public class Fragment_1 extends Fragment{ @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // TODO Auto-generated method stub View view = inflater.inflate(R.layout.fragment_fragment_1, container, false); final EditText edtxtPersonName_Fragment = (EditText) view.findViewById(R.id.edtxtPersonName); Button btnSayHi_Fragment = (Button) view.findViewById(R.id.btnSayHi); btnSayHi_Fragment.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub String name = edtxtPersonName_Fragment.getText().toString(); FragmentManager fm = getFragmentManager(); Fragment_2 f2 = (Fragment_2) fm.findFragmentById(R.id.fragment_content_2); if(f2 != null && f2.isInLayout()) { f2.setName(name); } Activity activity = getActivity(); if(activity != null) { Toast.makeText(activity, "Say&ing Hi in Progress...", Toast.LENGTH_LONG).show(); } } }); return view; } } ``` Fragment_2.Java ``` public class Fragment_2 extends Fragment{ View view; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // TODO Auto-generated method stub view = inflater.inflate(R.layout.fragment_fragment_2, container, false); return view; } public void setName(String name) { TextView txtName = (TextView) view.findViewById(R.id.txtViewResult); txtName.setText("Hi " + name); } } ``` When I run the application, there are whole lot of exceptions.. Here is the logcat trace.. ``` 04-16 15:06:48.781: E/AndroidRuntime(420): FATAL EXCEPTION: main 04-16 15:06:48.781: E/AndroidRuntime(420): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.fragmentexample/com.example.fragmentexample.MainActivity}: android.view.InflateException: Binary XML file line #5: Error inflating class fragment 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread.access$500(ActivityThread.java:122) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.os.Handler.dispatchMessage(Handler.java:99) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.os.Looper.loop(Looper.java:132) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread.main(ActivityThread.java:4123) 04-16 15:06:48.781: E/AndroidRuntime(420): at java.lang.reflect.Method.invokeNative(Native Method) 04-16 15:06:48.781: E/AndroidRuntime(420): at java.lang.reflect.Method.invoke(Method.java:491) 04-16 15:06:48.781: E/AndroidRuntime(420): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841) 04-16 15:06:48.781: E/AndroidRuntime(420): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599) 04-16 15:06:48.781: E/AndroidRuntime(420): at dalvik.system.NativeStart.main(Native Method) 04-16 15:06:48.781: E/AndroidRuntime(420): Caused by: android.view.InflateException: Binary XML file line #5: Error inflating class fragment 04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:688) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.rInflate(LayoutInflater.java:724) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.inflate(LayoutInflater.java:479) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.inflate(LayoutInflater.java:391) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.inflate(LayoutInflater.java:347) 04-16 15:06:48.781: E/AndroidRuntime(420): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:223) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Activity.setContentView(Activity.java:1786) 04-16 15:06:48.781: E/AndroidRuntime(420): at com.example.fragmentexample.MainActivity.onCreate(MainActivity.java:12) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Activity.performCreate(Activity.java:4397) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779) 04-16 15:06:48.781: E/AndroidRuntime(420): ... 11 more 04-16 15:06:48.781: E/AndroidRuntime(420): Caused by: android.app.Fragment$InstantiationException: Unable to instantiate fragment com.example.fragmentexample.fragment_fragment_1: make sure class name exists, is public, and has an empty constructor that is public 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Fragment.instantiate(Fragment.java:567) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Fragment.instantiate(Fragment.java:535) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Activity.onCreateView(Activity.java:4168) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:664) 04-16 15:06:48.781: E/AndroidRuntime(420): ... 21 more 04-16 15:06:48.781: E/AndroidRuntime(420): Caused by: java.lang.ClassNotFoundException: com.example.fragmentexample.fragment_fragment_1 in loader dalvik.system.PathClassLoader[/data/app/com.example.fragmentexample-1.apk] 04-16 15:06:48.781: E/AndroidRuntime(420): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:251) 04-16 15:06:48.781: E/AndroidRuntime(420): at java.lang.ClassLoader.loadClass(ClassLoader.java:540) 04-16 15:06:48.781: E/AndroidRuntime(420): at java.lang.ClassLoader.loadClass(ClassLoader.java:500) 04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Fragment.instantiate(Fragment.java:557) 04-16 15:06:48.781: E/AndroidRuntime(420): ... 24 more ``` I have seen examples on how to do it, but couldn't figure it out. Please point the regions where i am doing it wrong, and also please post the correct way of doing it. Thanks a lot for your time... EDIT ::: I have changed the MainActivity.java to extend FragmentActivity instead of Activity and also changed the android:name values in the activity_main.xml to point to Java Files instead of fragments... I get the following exceptions ::: ``` 04-16 15:29:43.821: E/AndroidRuntime(563): FATAL EXCEPTION: main 04-16 15:29:43.821: E/AndroidRuntime(563): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.fragmentexample/com.example.fragmentexample.MainActivity}: android.view.InflateException: Binary XML file line #5: Error inflating class fragment 04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread.access$500(ActivityThread.java:122) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.os.Handler.dispatchMessage(Handler.java:99) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.os.Looper.loop(Looper.java:132) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread.main(ActivityThread.java:4123) 04-16 15:29:43.821: E/AndroidRuntime(563): at java.lang.reflect.Method.invokeNative(Native Method) 04-16 15:29:43.821: E/AndroidRuntime(563): at java.lang.reflect.Method.invoke(Method.java:491) 04-16 15:29:43.821: E/AndroidRuntime(563): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841) 04-16 15:29:43.821: E/AndroidRuntime(563): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599) 04-16 15:29:43.821: E/AndroidRuntime(563): at dalvik.system.NativeStart.main(Native Method) 04-16 15:29:43.821: E/AndroidRuntime(563): Caused by: android.view.InflateException: Binary XML file line #5: Error inflating class fragment 04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:688) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.rInflate(LayoutInflater.java:724) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.inflate(LayoutInflater.java:479) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.inflate(LayoutInflater.java:391) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.inflate(LayoutInflater.java:347) 04-16 15:29:43.821: E/AndroidRuntime(563): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:223) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.Activity.setContentView(Activity.java:1786) 04-16 15:29:43.821: E/AndroidRuntime(563): at com.example.fragmentexample.MainActivity.onCreate(MainActivity.java:13) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.Activity.performCreate(Activity.java:4397) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779) 04-16 15:29:43.821: E/AndroidRuntime(563): ... 11 more 04-16 15:29:43.821: E/AndroidRuntime(563): Caused by: java.lang.ClassCastException: com.example.fragmentexample.Fragment_1 cannot be cast to android.support.v4.app.Fragment 04-16 15:29:43.821: E/AndroidRuntime(563): at android.support.v4.app.Fragment.instantiate(Fragment.java:394) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.support.v4.app.Fragment.instantiate(Fragment.java:369) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:272) 04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:660) 04-16 15:29:43.821: E/AndroidRuntime(563): ... 21 more ``` Here is the changed XML File of activity_main.xml ``` <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" > <fragment android:id="@+id/fragment_content_1" android:name="com.example.fragmentexample.Fragment_1" android:layout_width="fill_parent" android:layout_height="fill_parent" > </fragment> <fragment android:id="@+id/fragment_content_2" android:name="com.example.fragmentexample.Fragment_2" android:layout_width="fill_parent" android:layout_height="fill_parent" >  </fragment> </LinearLayout> ```

Original source