UI Android

package app.test;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import android.app.ProgressDialog;
import android.os.Handler;
import android.os.Message;
public class Test extends Activity {
  CharSequence[] items = { "Google", "Apple", "Microsoft" };
  boolean[] itemsChecked = new boolean [items.length];
  
    private ProgressDialog _progressDialog;
    private int _progress = 0;
    private Handler _progressHandler;    
  
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        Button btn = (Button) findViewById(R.id.btn_dialog);        
        btn.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                showDialog(1);
                _progress = 0;
                _progressDialog.setProgress(0);
                _progressHandler.sendEmptyMessage(0);
            }
        });
        _progressHandler = new Handler() {
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                if (_progress >= 100) {
                    _progressDialog.dismiss();
                } else {
                    _progress++;
                    _progressDialog.incrementProgressBy(1);
                    _progressHandler.sendEmptyMessageDelayed(0, 100);
                }
            }
        };
    }
    
    @Override
    protected Dialog onCreateDialog(int id) { 
        switch (id) {
        case 0:          
          return new AlertDialog.Builder(this)
          .setIcon(R.drawable.icon)
            .setTitle("This is a dialog with some simple text...")
            .setPositiveButton("OK", new 
                DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, 
                int whichButton) 
                {
                  Toast.makeText(getBaseContext(), 
                     "OK clicked!", Toast.LENGTH_SHORT).show();
                }
            })
            .setNegativeButton("Cancel", new 
                DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, 
                    int whichButton) 
                {
                  Toast.makeText(getBaseContext(), 
                        "Cancel clicked!", Toast.LENGTH_SHORT).show();
                }
            })            
            .setMultiChoiceItems(items, itemsChecked, new 
                DialogInterface.OnMultiChoiceClickListener() {          
          @Override
          public void onClick(DialogInterface dialog, int which, boolean isChecked) {
            Toast.makeText(getBaseContext(),
                  items[which] + (isChecked ? " checked!": " unchecked!"), 
                  Toast.LENGTH_SHORT).show();
          }
        }
            )
            .create();          
        case 1:
            _progressDialog = new ProgressDialog(this);
            _progressDialog.setIcon(R.drawable.icon);
            _progressDialog.setTitle("Downloading files...");
            _progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);            
            _progressDialog.setButton(DialogInterface.BUTTON_POSITIVE, "Hide", new 
                DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, 
                    int whichButton) 
                {
                  Toast.makeText(getBaseContext(), 
                        "Hide clicked!", Toast.LENGTH_SHORT).show();
                }
            });
            _progressDialog.setButton(DialogInterface.BUTTON_NEGATIVE, "Cancel", new 
                DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, 
                    int whichButton) 
                {
                  Toast.makeText(getBaseContext(), 
                        "Cancel clicked!", Toast.LENGTH_SHORT).show();
                }
            });
            return _progressDialog;
        }        
        return null;
    }
}
//main.xml

    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello" />    
    android:id="@+id/btn_dialog"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="Click to display a dialog" />