AlertDialog显示时间

import java.text.SimpleDateFormat;
import java.util.Date;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class main extends Activity  implements OnClickListener{
    /** Called when the activity is first created. */
    private Button btnshowDate;
    private Button btnshowTime;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btnshowDate=(Button)findViewById(R.id.btnShowDate);
        btnshowTime=(Button)findViewById(R.id.btnShowTime);
        
        btnshowDate.setOnClickListener(this);
        btnshowTime.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
         switch(v.getId()){
         case R.id.btnShowDate:
         {     SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
             showDialog("当前日期", sdf.format(new Date()));
           break;
         }
         case R.id.btnShowTime:
         {
             SimpleDateFormat sdf=new SimpleDateFormat("HH:mm；ss");
             showDialog("当前时间", sdf.format(new Date()));
                break;
         }
         }
    }
private void showDialog(String title,String msg){
  AlertDialog.Builder builder=new AlertDialog.Builder(this);
  builder.setIcon(android.R.drawable.ic_dialog_info);
  builder.setTitle(title);
  builder.setMessage(msg);
  builder.setPositiveButton("确定", null);
  builder.create().show();
  Intent intent;
}
}