When staring my app a list (list_main) is displayed in the master fragment. There is also a 2nd list fragment that is supposed to open when I clicking the 1st list item from my main list fragment, however after clicking the 1st list item, the main list fragment DOES disappear but the 2nd list does NOT appear hence the master fragment remains blank. Also when I click the back button, the main list does NOT reappear. Does anyone know why these issues are occurring and how they can be resolved?

Main Activity XML

<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"
    android:orientation="horizontal"
    android:showDividers="middle"
    tools:context=".MainActivity" >

    <fragment
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:id="@+id/master_container"
        android:name="com.apptacularapps.exitsexpertlondonlite.FragmentMainList"/>

    <FrameLayout
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="3"
        android:id="@+id/detail_container"/>

</LinearLayout>

Main List Fragment XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/fragmentmainlist">

    <ListView
        android:id="@+id/list_main"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerVertical="false"
        android:layout_centerHorizontal="true"/>
</LinearLayout>

Main List fragment class

import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;


public class FragmentMainList extends android.support.v4.app.Fragment {

    ListView list_main;

    String[] listContent = {
            "Item 1",
            "Item 2",
            "Item 3"
    };


    private boolean mTwoPane;

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
        View v = inflater.inflate(R.layout.fragment_main_list, container, false);
        list_main = (ListView)v.findViewById(R.id.list_main);

        list_main = (ListView)findViewById(R.id.list_main);
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,listContent);
        list_main.setAdapter(adapter);

        list_main.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {

                if (mTwoPane) {
                    for (int j = 0; j < adapterView.getChildCount(); j++)
                        adapterView.getChildAt(j).setBackgroundColor(Color.TRANSPARENT);

                    // change the background color of the selected list view item
                    view.setBackgroundColor(Color.parseColor("#00BCD4"));
                }


                if (position == 0) {
                    if (mTwoPane) {
                        FragmentItem1 newFragment = new FragmentItem1();
                        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

                        list_main.setVisibility(View.GONE);
                        transaction.replace(R.id.master_container, newFragment);
                        transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
                        transaction.addToBackStack(null);

                        transaction.commit();
                    } else {

                    }
                }

                if (position == 1) {

                }

                if (position == 2) {

                }
            }
        });

        return v;
    }
}

Main Activity class

public class MainActivity extends ActionBarActivity {

    ListView list_main;

    String[] listContent = {
            "Station Chooser",
            "Item 2",
            "Item 3"
    };

    private boolean mTwoPane;

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

        list_main = (ListView)findViewById(R.id.list_main);
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,listContent);
        list_main.setAdapter(adapter);

        list_main.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
                    if (position == 0) {
                    if (mTwoPane) {
                        FragmentStationChooser newFragment = new FragmentStationChooser();
                        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();


                        transaction.replace(R.id.master_container, newFragment);
                        transaction.addToBackStack(null);

                        transaction.commit();

                    getSupportFragmentManager().executePendingTransactions();
                    } else {

                    }
                }

                if (position == 1) {
                }

                if (position == 2) {
                }
            }
        });

        if (findViewById(R.id.detail_container) != null) {
            mTwoPane = true;
        }
    }
}

Station Chooser fragment

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ListView
        android:id="@+id/list_linechooser"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerVertical="false"
        android:layout_centerHorizontal="true"/>
</LinearLayout>

Station Chooser fragment class

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class FragmentStationChooser extends android.support.v4.app.Fragment {

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_station_chooser, container, false);
    }

}

Station Chooser Activity class

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.NavUtils;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class StationChooserActivity extends ActionBarActivity {

    ListView list_linechooser;

    String[] listContent = {
            "Line 1",
            "Line 2",
            "Line 3"
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_station_chooser);

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowHomeEnabled(false);

        list_linechooser = (ListView)findViewById(R.id.list_linechooser);
        list_linechooser.setAdapter(adapter);

        list_linechooser.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
            }
        });
    }

@Override
    public void onBackPressed() {
        if (mTwoPane) {
            FragmentMainList newFragment = new FragmentMainList();
            FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

            list_main.setVisibility(View.VISIBLE);
            transaction.replace(R.id.master_container, newFragment).commit();

            transaction.addToBackStack(null);
        }
    }
}