How to prevent a dialog from closing when a button is clicked

EDIT: This only works on API 8+ as noted by some of the comments.

This is a late answer, but you can add an onShowListener to the AlertDialog where you can then override the onClickListener of the button.

final AlertDialog dialog = new AlertDialog.Builder(context)
        .setView(v)
        .setTitle(R.string.my_title)
        .setPositiveButton(android.R.string.ok, null) //Set to null. We override the onclick
        .setNegativeButton(android.R.string.cancel, null)
        .create();

dialog.setOnShowListener(new DialogInterface.OnShowListener() {

    @Override
    public void onShow(DialogInterface dialogInterface) {

        Button button = ((AlertDialog) dialog).getButton(AlertDialog.BUTTON_POSITIVE);
        button.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                // TODO Do something

                //Dismiss once everything is OK.
                dialog.dismiss();
            }
        });
    }
});
dialog.show();