Showing json result in multiple pages using View Pagers and ListActivity

Question

Currently I am fetching result in JSON format in ListActivity and adding them in 4 ArrayList. I have set ViewPagers for four different pages. My layout is as:

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

    <ListView
        android:id="@android:id/list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" /> 

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/bg_gradient" />

</LinearLayout>

I have array lists as

  ArrayList<HashMap<String, String>> itemKB,itemMU,itemMI,itemRS;

onCreate method:

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

     ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
     viewPager.setAdapter(new CustomPagerAdapter(this));


    itemKB = new ArrayList<HashMap<String, String>>();   
    itemMU = new ArrayList<HashMap<String, String>>();   
    itemMI = new ArrayList<HashMap<String, String>>();   
    itemRS = new ArrayList<HashMap<String, String>>();   
    new LoadItems().execute();
 }

PostExecute of the Class that fetches the result is as:

         protected void onPostExecute(String file_url) {
            pDialog.dismiss();
            runOnUiThread(new Runnable() {
                public void run() {                   
                    ListAdapter adapter1 = new SimpleAdapter(
                     FetchItems.this, itemMI, R.layout.menu_kacha_bazaar, new String[] {TAG_ITEM_NAME,TAG_CATEGORY},new int[] 
                                     { R.id.itemName, 
                                       R.id.category
                                     });

                    ListAdapter adapter2 = new SimpleAdapter(
                         FetchItems.this, itemMU, R.layout.menu_mudi, new String[] {TAG_ITEM_NAME,TAG_CATEGORY},new int[] 
                                         { R.id.itemName, 
                                           R.id.category
                                         });
                    ListAdapter adapter3 = new SimpleAdapter(
                         FetchItems.this, itemKB, R.layout.menu_mishti, new String[] {TAG_ITEM_NAME,TAG_CATEGORY},new int[] 
                                         { R.id.itemName, 
                                           R.id.category
                                         });

                    ListAdapter adapter4 = new SimpleAdapter(
                         FetchItems.this, itemRS, R.layout.menu_rannar_sarjam, new String[] {TAG_ITEM_NAME,TAG_CATEGORY},new int[] 
                                         { R.id.itemName, 
                                           R.id.category
                                         });     

                     setListAdapter(adapter1);
                     //setListAdapter(adapter2);
                     //setListAdapter(adapter3);
                     //setListAdapter(adapter4);                      
            }
        });

    }

Now the problem is if I don't call the class that fetches the result, the view pager works fine, I can swipe across the pages.

But when I call the class that fetches the result,the view pager doesn't work.

I mean if I call all 4 setListAdapter,

setListAdapter(adapter1);
setListAdapter(adapter2);
setListAdapter(adapter3);
setListAdapter(adapter4); 

It displays the fourth page only and I am unable to swipe to any pages.

If I call just one setListAdapter,

 setListAdapter(adapter1);
 //setListAdapter(adapter2);
//setListAdapter(adapter3);
//setListAdapter(adapter4);   

I can see only the first page and again I can't swipe across pages.

Googled for this and found it can be done using Fragment, but I don't want more code changes.Can anyone help me out fixing this.

My CustomPagerAdapter is as:

import android.content.Context;
import android.support.v4.view.PagerAdapter;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class CustomPagerAdapter extends PagerAdapter {

    private Context mContext;

    public CustomPagerAdapter(Context context) {
        mContext = context;
    }

    @Override
    public Object instantiateItem(ViewGroup collection, int position) {
        CustomPagerEnum customPagerEnum = CustomPagerEnum.values()[position];
        LayoutInflater inflater = LayoutInflater.from(mContext);
        ViewGroup layout = (ViewGroup) inflater.inflate(customPagerEnum.getLayoutResId(), collection, false);
        collection.addView(layout);
        return layout;
    }

    @Override
    public void destroyItem(ViewGroup collection, int position, Object view) {
        collection.removeView((View) view);
    }

    @Override
    public int getCount() {
        return CustomPagerEnum.values().length;
    }


    @Override
    public CharSequence getPageTitle(int position) {
        CustomPagerEnum customPagerEnum = CustomPagerEnum.values()[position];
        return mContext.getString(customPagerEnum.getTitleResId());
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == object;

    }

}

Edit 1: Adding Layout code: Those layouts are as:

`<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#5fb0c9"
    android:orientation="vertical"
    android:scrollbarAlwaysDrawVerticalTrack="true" >

    <RelativeLayout
        android:id="@+id/relativeLayout1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_marginTop="40dp"
        android:background="#fff"
        android:orientation="vertical"
        android:padding="20dp" >

        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:paddingTop="30dp" >

            <TextView
                android:id="@+id/title"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:paddingLeft="50dp"
                android:textSize="17dip"
                android:text="Kacha Bazaar"
                android:textStyle="bold" />

            <TextView
                android:id="@+id/itemName"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:paddingLeft="50dp"
                android:textSize="17dip"
                android:textStyle="bold" />

            <TextView
                android:id="@+id/category"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:paddingLeft="50dp"
                android:paddingTop="30dp" />
        </LinearLayout>
    </RelativeLayout>

</ScrollView>`