Question

I’m just trying to follow along with the example code on android dev to inflate a fragment in an activity. I have a more complicated project I’m working but I’m getting the same error as this simple one here. Can anyone point me in the right direction?

The class that extends fragment

package com.example.fragtest;


import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class FragOne extends Fragment {

    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
    }
    @Override
    public View onCreateView(LayoutInflater inflater,ViewGroup container, Bundle savedInstanceState){
        return inflater.inflate(R.layout.activity_main, container,false);
    }

}

The class that extends FragmentActivity

package com.example.fragtest;

import android.os.Bundle;
import android.view.Menu;
import android.support.v4.app.FragmentActivity;

public class MainActivity extends FragmentActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }



}

The xml where the fragment is

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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 android:name="com.example.fragtest.FragOne"
       android:id="@+id/frag"
       android:layout_width="match_parent"
       android:layout_height="match_parent" />

</LinearLayout>

The manifest where the activity name is set

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.fragtest"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="11"
        android:targetSdkVersion="15" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/title_activity_main" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Here is the logcat output

07-17 23:45:09.053: E/AndroidRuntime(560): FATAL EXCEPTION: main
07-17 23:45:09.053: E/AndroidRuntime(560): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.fragtest/com.example.fragtest.MainActivity}: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.app.ActivityThread.access$600(ActivityThread.java:122)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.os.Handler.dispatchMessage(Handler.java:99)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.os.Looper.loop(Looper.java:137)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.app.ActivityThread.main(ActivityThread.java:4340)
07-17 23:45:09.053: E/AndroidRuntime(560):  at java.lang.reflect.Method.invokeNative(Native Method)
07-17 23:45:09.053: E/AndroidRuntime(560):  at java.lang.reflect.Method.invoke(Method.java:511)
07-17 23:45:09.053: E/AndroidRuntime(560):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
07-17 23:45:09.053: E/AndroidRuntime(560):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
07-17 23:45:09.053: E/AndroidRuntime(560):  at dalvik.system.NativeStart.main(Native Method)
07-17 23:45:09.053: E/AndroidRuntime(560): Caused by: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:697)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.view.LayoutInflater.rInflate(LayoutInflater.java:739)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
07-17 23:45:09.053: E/AndroidRuntime(560):  at com.example.fragtest.FragOne.onCreateView(FragOne.java:18)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:846)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1061)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1160)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:272)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:669)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.view.LayoutInflater.rInflate(LayoutInflater.java:739)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
07-17 23:45:09.053: E/AndroidRuntime(560):  at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:251)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.app.Activity.setContentView(Activity.java:1835)
07-17 23:45:09.053: E/AndroidRuntime(560):  at com.example.fragtest.MainActivity.onCreate(MainActivity.java:12)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.app.Activity.performCreate(Activity.java:4465)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
07-17 23:45:09.053: E/AndroidRuntime(560):  ... 11 more
07-17 23:45:09.053: E/AndroidRuntime(560): Caused by: java.lang.IllegalArgumentException: Binary XML file line #7: Duplicate id 0x7f080000, tag null, or parent id 0x0 with another fragment for com.example.fragtest.FragOne
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:277)
07-17 23:45:09.053: E/AndroidRuntime(560):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:669)
07-17 23:45:09.053: E/AndroidRuntime(560):  ... 30 more

Answer 1

In your Class that extends FragmentActivity you are setting the view to an XML file titled activity_main. Inside of activity_main you have a reference to your Fragment code, com.example.fragtest.FragOne.
When that XML is loaded, the code associated with com.example.fragtest.FragOne is executed. That Fragment‘s code returns a View with the R.id.activity_main.

That XML file has a reference to the same Fragment code that had just instantiated it. You see the conundrum.

To resolve your issue instance a new XML file (one that is not named activity_main) in your Fragment class. Instead of inflating activity_main inflate a separate XML (one that does not contain a reference to the code that called it). Effectively activity_main should be the container, this new layout (for instance fragment_layout) will be the UI portion.

I like to think of it like this: Despite doctrine, a Fragment has three portions. The container Activity (this can, and in your case should, inflate a layout XML file via setContentView), the Fragment‘s java code (this can, and in your case should, inflate a layout….something other than activity_main), and that Fragment‘s associated XML file (the one that is inflated by your Fragment class, don’t include a cyclical reference back to it’s code).

There are, of course, loopholes to these mantras but you get the drift?