how to add button in custom row listview i want to delete database selected entry in listview

xml for save database please help me to## i want add delete button in listview's each row when button is pressed delete that data from listview and database ##

here is first xml file

<LinearLayout xmlns:android="http://ift.tt/nIICcg"
xmlns:tools="http://ift.tt/LrGmb4"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#F3CAE5"
android:orientation="vertical"
android:padding="5dp" >

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <TextView
        android:id="@+id/frst_txtV"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="First name"
        android:textColor="#000" />

    <EditText
        android:id="@+id/frst_editTxt"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@+id/frst_txtV" />
</LinearLayout>

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <TextView
        android:id="@+id/lst_txtV"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:text="Last name"
        android:textColor="#000" />

    <EditText
        android:id="@+id/last_editTxt"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:layout_toRightOf="@+id/lst_txtV" />
</LinearLayout>

<Button
    android:id="@+id/save_btn"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:layout_marginTop="10dp"
    android:text="Save"
    android:textColor="#000" />

</LinearLayout>

display_activty.xml list view xml

<RelativeLayout xmlns:android="http://ift.tt/nIICcg"
xmlns:tools="http://ift.tt/LrGmb4"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#B58897"
android:gravity="center_horizontal" >

<Button
    android:id="@+id/btnAdd"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
    android:layout_marginRight="10dp"
    android:layout_marginTop="10dp"
    android:text="Add" />

<View
    android:id="@+id/a"
    android:layout_width="match_parent"
    android:layout_height="1dp"
    android:layout_below="@+id/btnAdd"
    android:background="#8DB3E1" />

<ListView
    android:id="@+id/List"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_below="@+id/a"
    android:divider="#8DB3E1"
    android:dividerHeight="2dp" />

</RelativeLayout>

displayadapter.java here i add button if i press button than record is will delete from database as well from listview

public class DisplayAdapter extends BaseAdapter {
private Context mContext;
private ArrayList<String> id;
private SQLiteDatabase dataBase;
private ArrayList<String> firstName;
private ArrayList<String> lastName;



public DisplayAdapter(Context c, ArrayList<String> id,ArrayList<String> fname, ArrayList<String> lname) {
    this.mContext = c;

    this.id = id;
    this.firstName = fname;
    this.lastName = lname;
}

public int getCount() {
    // TODO Auto-generated method stub
    return id.size();
}

public Object getItem(int position) {
    // TODO Auto-generated method stub
    return null;
}

public long getItemId(int position) {
    // TODO Auto-generated method stub
    return 0;
}

public View getView(final int pos, View child, ViewGroup parent) {
    Holder mHolder;
    LayoutInflater layoutInflater;
    if (child == null) {
        layoutInflater = (LayoutInflater)     mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        child = layoutInflater.inflate(R.layout.listcell, null);
        mHolder = new Holder();
        mHolder.txt_id = (TextView) child.findViewById(R.id.txt_id);
        mHolder.txt_fName = (TextView) child.findViewById(R.id.txt_fName);

        mHolder.txt_lName = (TextView) child.findViewById(R.id.txt_lName);
        mHolder.btn = (Button) child.findViewById(R.id.Button1);

        child.setTag(mHolder);
    } else {
        mHolder = (Holder) child.getTag();
    }
    mHolder.txt_id.setText(id.get(pos));
    mHolder.txt_fName.setText(firstName.get(pos));
    mHolder.txt_lName.setText(lastName.get(pos));
    mHolder.btn.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) 
        {

        }
    });


    return child;
}

public class Holder {
    TextView txt_id;
    TextView txt_fName;
    TextView txt_lName;
    Button btn;

    //ImageView img;
}
}

listcell.xml this is to display custom listview xml file

<LinearLayout xmlns:android="http://ift.tt/nIICcg"
xmlns:tools="http://ift.tt/LrGmb4"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#F3CAE5"
android:gravity="center_vertical"
android:orientation="horizontal"
android:padding="8dp" >

<TextView
    android:id="@+id/txt_id"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:textColor="#000" />

<TextView
    android:id="@+id/txt_fName"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_weight="2"
    android:textColor="#000" />

<TextView
    android:id="@+id/txt_lName"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_weight="2"
    android:textColor="#000" />

<Button android:text="Button"
    android:id="@+id/Button1"
    android:focusable="false"

    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    />

</LinearLayout>

DisplayActivty.java here is listview adding class

public class DisplayActivity extends Activity {

private DbHelper mHelper;
private SQLiteDatabase dataBase;


private ArrayList<String> userId = new ArrayList<String>();
private ArrayList<String> user_fName = new ArrayList<String>();
private ArrayList<String> user_lName = new ArrayList<String>();

private ListView userList;

private AlertDialog.Builder build;

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

    userList = (ListView) findViewById(R.id.List);


    mHelper = new DbHelper(this);


    //add new record
    findViewById(R.id.btnAdd).setOnClickListener(new OnClickListener() 
    {

        public void onClick(View v) {

            Intent i = new Intent(getApplicationContext(),
                    AddActivity.class);
            i.putExtra("update", false);
            startActivity(i);

        }
    });

    //click to update data
    userList.setOnItemClickListener(new OnItemClickListener() {

        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {

            Intent i = new Intent(getApplicationContext(),
                    AddActivity.class);
            i.putExtra("Fname", user_fName.get(arg2));
            i.putExtra("Lname", user_lName.get(arg2));
            i.putExtra("ID", userId.get(arg2));
            i.putExtra("update", true);
            startActivity(i);


        }
    });
}

@Override
protected void onResume() {
    displayData();
    super.onResume();
}

/**
 * displays data from SQLite
 */
private void displayData() {
    dataBase = mHelper.getWritableDatabase();
    Cursor mCursor = dataBase.rawQuery("SELECT * FROM "
            + DbHelper.TABLE_NAME, null);

    userId.clear();
    user_fName.clear();
    user_lName.clear();
    if (mCursor.moveToFirst()) {
        do {
              userId.add(mCursor.getString(mCursor.getColumnIndex(DbHelper.KEY_ID)));
            user_fName.add(mCursor.getString(mCursor.getColumnIndex(DbHelper.KEY_FNAME)));
            user_lName.add(mCursor.getString(mCursor.getColumnIndex(DbHelper.KEY_LNAME)));

        } while (mCursor.moveToNext());
    }
    DisplayAdapter disadpt = new DisplayAdapter(DisplayActivity.this,userId, user_fName, user_lName);
    userList.setAdapter(disadpt);
    mCursor.close();
}

}

Addactivty.java add database class

public class AddActivity extends Activity implements OnClickListener {
private Button btn_save;
private EditText edit_first,edit_last;
private DbHelper mHelper;
private SQLiteDatabase dataBase;
private String id,fname,lname;
private boolean isUpdate;

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

    btn_save=(Button)findViewById(R.id.save_btn);
    edit_first=(EditText)findViewById(R.id.frst_editTxt);
    edit_last=(EditText)findViewById(R.id.last_editTxt);

   isUpdate=getIntent().getExtras().getBoolean("update");
    if(isUpdate)
    {
        id=getIntent().getExtras().getString("ID");
        fname=getIntent().getExtras().getString("Fname");
        lname=getIntent().getExtras().getString("Lname");
        edit_first.setText(fname);
        edit_last.setText(lname);

    }

     btn_save.setOnClickListener(this);

     mHelper=new DbHelper(this);

}

// saveButton click event 
public void onClick(View v) {
    fname=edit_first.getText().toString().trim();
    lname=edit_last.getText().toString().trim();
    if(fname.length()>0 && lname.length()>0)
    {
        saveData();
    }
    else
    {
        AlertDialog.Builder alertBuilder=new     AlertDialog.Builder(AddActivity.this);
        alertBuilder.setTitle("Invalid Data");
        alertBuilder.setMessage("Please, Enter valid data");
        alertBuilder.setPositiveButton("Ok", new DialogInterface.OnClickListener() {

            public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();

            }
        });
        alertBuilder.create().show();
    }

}

/**
 * save data into SQLite
 */
private void saveData(){
    dataBase=mHelper.getWritableDatabase();
    ContentValues values=new ContentValues();

    values.put(DbHelper.KEY_FNAME,fname);
    values.put(DbHelper.KEY_LNAME,lname );

    System.out.println("");
    if(isUpdate)
    {    
        //update database with new data 
        dataBase.update(DbHelper.TABLE_NAME, values, DbHelper.KEY_ID+"="+id, null);
    }
    else
    {
        //insert data into database
        dataBase.insert(DbHelper.TABLE_NAME, null, values);
    }
    //close database
    dataBase.close();
    finish();


  }

}