alertdialog show in android

1  AlertDialog.Builder builder = new AlertDialog.Builder(this);
2        builder.setMessage(getResources().getString(R.string.do_you_really_want_to_signout));
3        builder.setTitle(getResources().getString(R.string.sign_out));
4        builder.setCancelable(false);
5        builder.setNegativeButton(getResources().getString(R.string.cancel), new DialogInterface.OnClickListener() {
6            public void onClick(DialogInterface dialog, int which) {
7                dialog.cancel();
8            }
9        });
10        builder.setPositiveButton(getResources().getString(R.string.sure), new DialogInterface.OnClickListener() {
11            public void onClick(DialogInterface dialog, int which) {
12                Toast.makeText(AccountActivity.this, R.string.log_out_success,
13                        Toast.LENGTH_LONG).show();
14               
15            }
16        });
17
18        AlertDialog alert = builder.create();
19        alert.show();