Int firstIndexOfPreviusPage = firstIndexOfCurrentPage - (bufferSize / 3) Int firstIndexOfCurrentPage = pageSize * (currentPage - 1) * the index of the previous page's first element * Calculates the index of the previous page's first element * clears the map except the first element that MUST be kept LoadedData.put((startRow + j), (T) results.get(j)) List results = dataAdapter.getBufferedData(startRow, numElementToFind) NumElementToFind = totalResultsNumber - startRow This.totalResultsNumber = totalResultsNumber Public LazyLoadingList(IDataProvider dataProvider, int pageSize, int totalResultsNumber) * totalResultsNumber, the total number of rows as result of the database count query. * pageSize, the number of rows to be showed in a table page * dataProvider, the object that will perform the query * class LazyLoadingList extends AbstractList * If pageSize is equals to totalResultsNumber, the dataTable will be non paginated: the first query will retrieve all the dataset. * This list loads and stores only the first page and the current page.
This parameter 'is usually the result of a count query. Note that the constructor of the list accepts as incoming parameter totalResultsNumber, that is the total number of results to show in the table. When the user navigates in the following pages, they will be retrieved by method get() and saved in a different list. This list keeps in memory a list of objects corresponding to the first page. They will be initialized in the page backingBean and used in this way in the. Let's see three possible implementations to implement the lazy loading of the list. The solution is to manage the list of results in a lazy way: the list itself will retrieve the records to show in the current page and only when there will be a real need.īesides this, we need also to manage the total page number: the paginator in fact invokes the method size() of the list supplied to the table calculates the number of pages. The main weakness of this component lies in the difficulty to handle large data sets: ice:dataTable component need to receive a list containing all rows that will gradually showed.Īs long as we are in the order of some hundreds of records, there is no problem to provide the entire results list to the component but if they begin to be thousands, keep in memory such a quantity of objects can be an issue. This component, together with ice:dataPaginator makes it possible to paginate the entire data set of a table, showing only N rows per page. IceFaces provides numerous components to facilitate the development of web applications.Īmong these, one of the most 'useful' is definitely ice:dataTable.
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