Question

Do you know this feeling when every code you write works immedietly and you underrun your schedule 😛 It’s like ‘oh yeah now I have time to make it perfect’. That’s where I am at the moment^^

So I implemented a repeater with JSF (ui:repeat) and I thought about a paging for all the entities. Is there maybe an easy way to do that? What are the points I have to think about?

Would be nice if someone gives me some help. My googleskills haven’t helped me so far 😛

Cheers…

Answer 1

Here is a simple example that should give you the idea on how to implement this.

RepeatPaginator:

public class RepeatPaginator {

    private static final int DEFAULT_RECORDS_NUMBER = 2;
    private static final int DEFAULT_PAGE_INDEX = 1;

    private int records;
    private int recordsTotal;
    private int pageIndex;
    private int pages;
    private List<?> origModel;
    private List<?> model;

    public RepeatPaginator(List<?> model) {
        this.origModel = model;
        this.records = DEFAULT_RECORDS_NUMBER;
        this.pageIndex = DEFAULT_PAGE_INDEX;        
        this.recordsTotal = model.size();

        if (records > 0) {
            pages = records <= 0 ? 1 : recordsTotal / records;

            if (recordsTotal % records > 0) {
                pages++;
            }

            if (pages == 0) {
                pages = 1;
            }
        } else {
            records = 1;
            pages = 1;
        }

        updateModel();
    }

    public void updateModel() {
        int fromIndex = getFirst();
        int toIndex = getFirst() + records;

        if(toIndex > this.recordsTotal) {
            toIndex = this.recordsTotal;
        }

        this.model = origModel.subList(fromIndex, toIndex);
    }

    public void next() {
        if(this.pageIndex < pages) {
            this.pageIndex++;
        }

        updateModel();
    }

    public void prev() {
        if(this.pageIndex > 1) {
            this.pageIndex--;
        }

        updateModel();
    }   

    public int getRecords() {
        return records;
    }

    public int getRecordsTotal() {
        return recordsTotal;
    }

    public int getPageIndex() {
        return pageIndex;
    }

    public int getPages() {
        return pages;
    }

    public int getFirst() {
        return (pageIndex * records) - records;
    }

    public List<?> getModel() {
        return model;
    }

    public void setPageIndex(int pageIndex) {
        this.pageIndex = pageIndex;
    }

}

Bean:

public class TestBean {

    private List<String> list;
    private RepeatPaginator paginator;

    @PostConstruct
    public void init() {
        this.list = new ArrayList<String>();
        this.list.add("Item 1");
        this.list.add("Item 2");
        this.list.add("Item 3");
        this.list.add("Item 4");
        this.list.add("Item 5");
        this.list.add("Item 6");
        this.list.add("Item 7");
        this.list.add("Item 8");
        this.list.add("Item 9");
        this.list.add("Item 10");
        this.list.add("Item 11");
        paginator = new RepeatPaginator(this.list);
    }

    public RepeatPaginator getPaginator() {
        return paginator;
    }

}

XHTML:

<ui:composition xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:h="http://java.sun.com/jsf/html"
    template="/WEB-INF/template/default.xhtml">

<ui:define name="content">
    <h:form>
        <ui:repeat value="#{testBean.paginator.model}" var="listItem">
            <div>
                <h:outputText value="#{listItem}"/>
            </div>
        </ui:repeat>
        <h:commandButton value="&lt; prev" action="#{testBean.paginator.prev}"/>
        <h:outputText value="#{testBean.paginator.pageIndex} / #{testBean.paginator.pages}"/>
        <h:commandButton value="next &gt;" action="#{testBean.paginator.next}"/>
        <h:inputHidden value="#{testBean.paginator.pageIndex}"/>
    </h:form>
</ui:define>
</ui:composition>