title: android date picker from alert dialog
body: <p>I am trying to start a date picker from an alert dialog. but for some reason the showDialog(DATE_DIALOG_ID) doesn't open up at all. Could some please tell me what is wrong. </p>
  
  <pre><code>final AlertDialog.Builder alt_bld = new AlertDialog.Builder(this);
          alt_bld.setIcon(R.drawable.icon);
          alt_bld.setTitle("Categories");
          alt_bld.setSingleChoiceItems(categoryType, -1, new DialogInterface.OnClickListener() {
              public void onClick(DialogInterface dialog, int item) {
                  System.out.println("Category selected= "+categoryType[item]);
                  Toast.makeText(getApplicationContext(), "Category selected= "+categoryType[item], Toast.LENGTH_SHORT).show();
                  category=categoryType[item];
  
  
                  if(category.equalsIgnoreCase("Time")){
                      showDialog(DATE_DIALOG_ID);
                      System.out.println("selected date here:"+selectedDate);
                      Intent intent = new Intent(MainActivity.this, ListViewActivity.class);
                      bundle.putString("category", category);
                      bundle.putString("attribute", selectedDate);
                      intent.putExtras(bundle);
                      startActivity(intent);
  
                  }
  </code></pre>
  
  <p>other datepicker related code</p>
  
  <pre><code>static final int DATE_DIALOG_ID = 0;
  
  
  
  @Override
      protected Dialog onCreateDialog(int id) {
          switch (id) {
          case DATE_DIALOG_ID:
              return new DatePickerDialog(this,
                          mDateSetListener,
                          mYear, mMonth, mDay);
          }
          return null;
      }   
  
  
      private DatePickerDialog.OnDateSetListener mDateSetListener =
          new DatePickerDialog.OnDateSetListener() {
  
  
          public void onDateSet(DatePicker view, int year,
                                int monthOfYear, int dayOfMonth) {
              mYear = year;
              mMonth = monthOfYear;
              mDay = dayOfMonth;
              selectedDate = Integer.toString(mMonth)+"-"+Integer.toString(mDay)+"-"+Integer.toString(mYear);
              System.out.println("selected date is:"+selectedDate);
          }
  
  
      };
  
  public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.homescreen);
  
          final Calendar cal = Calendar.getInstance();
          mYear = cal.get(Calendar.YEAR);
          mMonth = cal.get(Calendar.MONTH);
          mDay = cal.get(Calendar.DAY_OF_MONTH);
  </code></pre>