Android: RuntimeException: Unable to start activity ComponentInfo

Question

I'm new to Android and i'm trying to adapt this Activity : ANDROID: EXPANDABLE LIST VIEW EXAMPLE to a Fragment so i can use it on a master-detail flow, and i keep getting this message:

FATAL EXCEPTION: main
E/AndroidRuntime(2391): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.expandablelistdemo/com.example.expandablelistdemo.MainActivity}: android.view.InflateException: Binary XML file line #12: Error inflating class fragment

This is my code:

Manifest

    <uses-sdk
        android:minSdkVersion="15"
        android:targetSdkVersion="19" />

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

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

</manifest>

MainActivity.java ( its the default activity )

package com.example.expandablelistdemo;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

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.main, menu);
        return true;
    }

}

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: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=".MainActivity" >


    <fragment
        android:id="@+id/item_list"
        android:name="com.example.expandablelistdemo.MainFragment"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1"
        tools:layout="@android:layout/list_content" />


</RelativeLayout>

MainFragment.java

package com.example.expandablelistdemo;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import android.app.Fragment;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnChildClickListener;
import android.widget.LinearLayout;
import android.widget.Toast;

public class MainFragment extends Fragment {

    List<String> groupList;
    List<String> childList;
    Map<String, List<String>> laptopCollection;
    ExpandableListView expListView;

    private LinearLayout ll;
    private FragmentActivity fa;

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    fa = (FragmentActivity) super.getActivity();
    ll = (LinearLayout) inflater.inflate(R.layout.fragment_main, container, false);

    return ll;
    }

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

        createGroupList();

        createCollection();

        expListView = (ExpandableListView) super.getActivity().findViewById(R.id.laptop_list);
        final ExpandableListAdapter expListAdapter = new ExpandableListAdapter(
                super.getActivity(), groupList, laptopCollection);
        expListView.setAdapter(expListAdapter);

        expListView.setOnChildClickListener(new OnChildClickListener() {

            public boolean onChildClick(ExpandableListView parent, View v,
                    int groupPosition, int childPosition, long id) {
                final String selected = (String) expListAdapter.getChild(
                        groupPosition, childPosition);
               // Toast.makeText(getBaseContext(), selected, Toast.LENGTH_LONG).show();

                return true;
            }
        });
    }

    private void createGroupList() {
        groupList = new ArrayList<String>();
        groupList.add("HP");
        groupList.add("Dell");
        groupList.add("Lenovo");
        groupList.add("Sony");
        groupList.add("HCL");
        groupList.add("Samsung");
    }

    private void createCollection() {
        // preparing laptops collection(child)
        String[] hpModels = { "HP Pavilion G6-2014TX", "ProBook HP 4540",
                "HP Envy 4-1025TX" };
        String[] hclModels = { "HCL S2101", "HCL L2102", "HCL V2002" };
        String[] lenovoModels = { "IdeaPad Z Series", "Essential G Series",
                "ThinkPad X Series", "Ideapad Z Series" };
        String[] sonyModels = { "VAIO E Series", "VAIO Z Series",
                "VAIO S Series", "VAIO YB Series" };
        String[] dellModels = { "Inspiron", "Vostro", "XPS" };
        String[] samsungModels = { "NP Series", "Series 5", "SF Series" };

        laptopCollection = new LinkedHashMap<String, List<String>>();

        for (String laptop : groupList) {
            if (laptop.equals("HP")) {
                loadChild(hpModels);
            } else if (laptop.equals("Dell"))
                loadChild(dellModels);
            else if (laptop.equals("Sony"))
                loadChild(sonyModels);
            else if (laptop.equals("HCL"))
                loadChild(hclModels);
            else if (laptop.equals("Samsung"))
                loadChild(samsungModels);
            else
                loadChild(lenovoModels);

            laptopCollection.put(laptop, childList);
        }
    }

    private void loadChild(String[] laptopModels) {
        childList = new ArrayList<String>();
        for (String model : laptopModels)
            childList.add(model);
    }

    // Convert pixel to dip
    public int getDipsFromPixel(float pixels) {
        // Get the screen's density scale
        final float scale = getResources().getDisplayMetrics().density;
        // Convert the dps to pixels, based on density scale
        return (int) (pixels * scale + 0.5f);
    }

    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        super.getActivity().getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
}

fragment_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"
    tools:context=".MainFragment" >

    <ExpandableListView
        android:id="@+id/laptop_list"
        android:layout_width="match_parent"
        android:layout_height="fill_parent" >
    </ExpandableListView>

</RelativeLayout>

There's 1 more java class and 2 layouts that are used inside the list but im sure those are not the issue.... i just can figure it out where is the problem

My best guess its the fa = (FragmentActivity) super.getActivity(); , that cast seems weird... or maybe its just me

Any help would be greatly appreciated!

Answer 1

Try extending MainActivity with FragmentActivity instead of just Activity . ie:

public class MainActivity extends FragmentActivity