Navigation drawer - Fragment is not showing
<p>EDITED -2</p>

<p>Its like the same one earlier, I tried to do what you did on the first one that I gave and searched some Instructions on converting an Activity to Fragment but all I get is a bunch of errors. Also, do you have a good source tutorial or information on converting this kinds of files? I would really much appreciate it. </p>

<pre><code>    public class Lesson111 extends Activity{

    private RadioGroup radioAnswerGroup;
    private RadioButton radioAnswerButton;
    private Button btnSubmit;

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

        addListenerOnButton();

    }

    public void addListenerOnButton() {

        radioAnswerGroup = (RadioGroup) findViewById(R.id.radioAnswer);
        btnSubmit = (Button) findViewById(R.id.btnSubmit);

        btnSubmit.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                // get selected radio button from radioGroup
                int selectedId = radioAnswerGroup.getCheckedRadioButtonId();

                // find the radiobutton by returned id
                radioAnswerButton = (RadioButton) findViewById(selectedId);

                Toast.makeText(Lesson111.this,
                        radioAnswerButton.getText(), Toast.LENGTH_SHORT).show();

            }

        });

    }
}
</code></pre>

<p>Here is the main activity</p>

<pre><code>public class NavigationActivity extends FragmentActivity {

    private DrawerLayout mDrawerLayout;
    ImageView home;
    Fragment fragment = null;
    TextView appname;
    ExpandableListView expListView;
    HashMap&lt;String, List&lt;String&gt;&gt; listDataChild;
    ExpandableListAdapter listAdapter;
    List&lt;String&gt; listDataHeader;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_navigation);
        home = (ImageView)findViewById(R.id.home);
        home.setOnClickListener(homeOnclickListener);
        appname = (TextView)findViewById(R.id.appname);
        setUpDrawer();
    }

    /**
     * 
     * Get the names and icons references to build the drawer menu...
     */
    private void setUpDrawer() {
        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        mDrawerLayout.setScrimColor(getResources().getColor(android.R.color.transparent));
        mDrawerLayout.setDrawerListener(mDrawerListener);
        expListView = (ExpandableListView) findViewById(R.id.lvExp);
        prepareListData();
        listAdapter = new ExpandableListAdapter(this, listDataHeader, listDataChild);
        // setting list adapter
        expListView.setAdapter(listAdapter);
        fragment = new Lesson1();
        getSupportFragmentManager().beginTransaction().replace(R.id.content_frame, fragment).commit();
        mDrawerLayout.closeDrawer(expListView);

        expListView.setOnChildClickListener(new OnChildClickListener() {
            @Override
            public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
                switch (groupPosition) {
                case 0:
                    switch (childPosition) {
                    case 0:
                        fragment = new Lesson1();
                        break;
                    case 1:
                        fragment = new Lesson11();
                        break;
                    case 2:
                        Activity activity = new Lesson111();
                        break;
                    default:
                        break;
                    }
                    break;
</code></pre>

<p>this is not the whole code. But i believe the reason why the fragment is not showing is because of this case statement. Did i missed something?</p>