attach

Public Class downloadAttachment {

    String recId;

    public downloadAttachment(ApexPages.StandardController controller) {
        recId = controller.getId();
    }

    public List<String> getfieldId() {
        List<String> li = new List<String>();
        System.debug(li.isEmpty());     // true
        List<Attachment> attachedFiles = [select Id from Attachment where parentId =:recId order By LastModifiedDate DESC ];
        if( attachedFiles != null && attachedFiles.size() > 0 ) {
        for (Integer i=0 ; i < attachedFiles.size(); i++) {

            fieldId.add(attachedFiles[i].Id);
            }
        }
        return fieldId;

    }
}