应该如何替换showDialog（0）？

Question

public class MainActivity extends Activity {

    CharSequence[] items={"google","apple","Microsoft"};
    boolean[] itemschecked=new boolean[items.length];

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

如何替换showDialog

    public void OnClick(View v)
    {
      showDialog(0);
    }
  @Override
      rotected Dialog onCreateDialog(int id)
  {switch(id)
      { case 0:
          Builder builder = new AlertDialog.Builder(this);
          builder.setIcon(R.drawable.ic_launcher);
          builder.setTitle("This is dialog with some simple text...");
          builder.setPositiveButton("OK",new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int whichButton) {
                Toast.makeText(getBaseContext(), "ok clicked!",Toast.LENGTH_SHORT).show();
              }
          }
       );

     builder.setNegativeButton("cancel",new DialogInterface.OnClickListener()
     {public void onClick(DialogInterface dialog,int whichButton)
     {Toast.makeText(getBaseContext(), "cancel clicked!", Toast.LENGTH_SHORT).show();
     }
    }
    ); 

 builder.setMultiChoiceItems(items, itemschecked, new DialogInterface.OnMultiChoiceClickListener()
 {public void onClick(DialogInterface dialog,int which,boolean ischecked)
 { Toast.makeText(getBaseContext(), items[which]+(ischecked ? "checked!" :" unchecked!"),Toast.LENGTH_SHORT).show();
 }
 }
 );

return builder.create();
      }
  return null;
  }
    }