Android : custom font (unicode) in Custom ListView Adapter doesn't show

I want to create a custom list adapter with Unicode. this is my code and it compiles without any errors but its Unicode characters didn't show. Please help me to rectify the problem. Thanks you.

CustomListViewAdapter

package com.theopentutorials.android.beans;

import java.util.List;

import com.theopentutorials.android.R;
import com.theopentutorials.android.beans.RowItem;

import android.app.Activity;
import android.content.Context;
import android.graphics.Typeface;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class CustomListViewAdapter extends ArrayAdapter<RowItem> {

    Context context;

    public CustomListViewAdapter(Context context, int resourceId,
            List<RowItem> items) {
        super(context, resourceId, items);
        this.context = context;
    }

    /* private view holder class */
    private class ViewHolder {
        ImageView imageView;
        TextView txtTitle;
        TextView txtDesc;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        RowItem rowItem = getItem(position);

        LayoutInflater mInflater = (LayoutInflater) context
                .getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.list_item, null);
            holder = new ViewHolder();
            holder.txtDesc = (TextView) convertView.findViewById(R.id.desc);
            holder.txtTitle = (TextView) convertView.findViewById(R.id.title);
            holder.imageView = (ImageView) convertView.findViewById(R.id.icon);
            convertView.setTag(holder);
        } else
            holder = (ViewHolder) convertView.getTag();

        holder.txtDesc.setText(rowItem.getDesc());
        holder.txtTitle.setText(rowItem.getTitle());
        holder.imageView.setImageResource(rowItem.getImageId());

        return convertView;
    }
}

ImageTextListViewActivity

    package com.theopentutorials.android.beans;

import java.util.ArrayList;
import java.util.List;

import com.theopentutorials.android.R;

import android.app.Activity;
import android.graphics.Typeface;
import android.os.Bundle;
import android.view.Gravity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

public class ImageTextListViewActivity extends Activity implements
        OnItemClickListener {

    public static final String[] titles = new String[] { "කළමනාකාරීත්වයක්",
            "පරිසරයට", "සමාගම ", "XXXXXX " };

    public static final String[] descriptions = new String[] {
            "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
            "cccccccccccccccccccccccccccccc", "dddddddddddddddddddddddddddddd" };

    public static final Integer[] images = { R.drawable.straw,
            R.drawable.banana, R.drawable.orange, R.drawable.mixed };

    ListView listView;
    List<RowItem> rowItems;
    public Typeface myTypeface;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        myTypeface = Typeface
                .createFromAsset(getAssets(), "fonts/iskpotab.ttf");

        EditText edt1 = (EditText) findViewById(R.id.editText1);
        edt1.setText("කළමනාකාරීත්වයක්");

        edt1.setTypeface(myTypeface);

        rowItems = new ArrayList<RowItem>();
        for (int i = 0; i < titles.length; i++) {
            RowItem item = new RowItem(images[i], titles[i], descriptions[i]);
            rowItems.add(item);
        }

        listView = (ListView) findViewById(R.id.list);

        CustomListViewAdapter adapter = new CustomListViewAdapter(this,
                R.layout.list_item, rowItems);

        listView.setAdapter(adapter);

        listView.setOnItemClickListener(this);
    }

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position,
            long id) {
        Toast toast = Toast.makeText(getApplicationContext(), "Item "
                + (position + 1) + ": " + rowItems.get(position),
                Toast.LENGTH_SHORT);
        toast.setGravity(Gravity.BOTTOM | Gravity.CENTER_HORIZONTAL, 0, 0);
        toast.show();
    }
}

RowItem

    package com.theopentutorials.android.beans;
public class RowItem {
    private int imageId;
    private String title;
    private String desc;

    public RowItem(int imageId, String title, String desc) {
        this.imageId = imageId;
        this.title = title;
        this.desc = desc;
    }
    public int getImageId() {
        return imageId;
    }
    public void setImageId(int imageId) {
        this.imageId = imageId;
    }
    public String getDesc() {
        return desc;
    }
    public void setDesc(String desc) {
        this.desc = desc;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    @Override
    public String toString() {
        return title + "\n" + desc;
    }   
}
    package com.theopentutorials.android.beans;

import java.util.HashMap;
import java.util.List;

import com.theopentutorials.android.R;

import android.content.Context;
import android.graphics.Typeface;
import android.view.View;
import android.view.ViewGroup;
import android.widget.SimpleAdapter;
import android.widget.TextView;

public class SpecialAdapter extends SimpleAdapter {
    public SpecialAdapter(Context context, List<HashMap<String, String>> items,
            int resource, String[] from, int[] to) {
        super(context, items, resource, from, to);
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        View view = super.getView(position, convertView, parent);

        ((TextView) view.findViewById(R.id.desc)).setTypeface(Typeface
                .createFromAsset(view.getContext().getAssets(),
                        "fonts/iskpotab.ttf"));

        ((TextView) view.findViewById(R.id.title)).setTypeface(Typeface
                .createFromAsset(view.getContext().getAssets(),
                        "fonts/iskpotab.ttf"));

        return view;
    }
}