Paging the list collection

list Paging tools

	/** *  Start paging  * @param list * @param pageNum  Page number  * @param pageSize  How many pieces of data per page  */
    public static List startPage(List list, Integer pageNum, Integer pageSize) {
    
        if (list == null) {
    
            return null;
        }
        if (list.size() == 0) {
    
            return null;
        }

        Integer count = list.size(); //  Record the total number 
        Integer pageCount = 0; //  the number of pages 
        if (count % pageSize == 0) {
    
            pageCount = count / pageSize;
        } else {
    
            pageCount = count / pageSize + 1;
        }

        int fromIndex = 0; //  Start index 
        int toIndex = 0; //  End index 

        if (!pageNum.equals(pageCount)) {
    
            fromIndex = (pageNum - 1) * pageSize;
            toIndex = fromIndex + pageSize;
        } else {
    
            fromIndex = (pageNum - 1) * pageSize;
            toIndex = count;
        }

        List pageList = list.subList(fromIndex, toIndex);

        return pageList;
    }