List view with Multi select Items Android

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;

/**
 * Demo Activity that will display the ListView and footer.
 * @author techin
 */

public class Demo extends Activity {

 ListView listView;
 TextView textView;
 Button Ok;
 String array[]=new String[]{"a","b","c","d","e","f","g","h","i"};
 String temp;
 
 @Override
 public void onCreate(Bundle savedInstanceState) {

  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);


  listView = (ListView)findViewById(R.id.ListView01);
  textView = (TextView)findViewById(R.id.TextView01);
  Ok = (Button)findViewById(R.id.okBT);

  /**
   * Setting ListView adapter using AttayAdapter.
   */

  listView.setAdapter(new ArrayAdapter<String>(this,android.R.layout.simple_list_item_multiple_choice,array));
  listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
  
  /**
   * OK button on click Listener.
   */
  
  Ok.setOnClickListener(new View.OnClickListener(){

   public void onClick(View v) {
    System.out.println("check Items:"+listView.getCheckItemIds().length);
    getSelectedItems(listView.getCheckItemIds().length);
   }
  });
 }
 
 /**
  * Method to get Selected Items from the ListView.
  * @param length - Length of the number of CheckBox that are selected.
  */
 
 private void getSelectedItems(int length){
  temp="";
  for(int i=0;i<length;i++){
    temp+=array[(int) listView.getCheckItemIds()[i]];
  }
  textView.setText(temp);
 }
}