How to dynamically create selecItems in a pgae from a table

Question

To those who may be able to help:
I am using JDeveloper 10.1.3.4. In my application, I need to put a number of selectItem tags such as radio buttons on a page. What is difficult about this is that it can not be known in advance how many radio buttons there will be, because is depends on how many rows will be selected from a table, even though it is known that the number of selected rows will not exceed 3. I am considering using the radio button because it looks better on the page, and the user must select only one.
A few sample rows from the table:
TERM    AVAILABLE  SWITCHED
200809  N          OFF
200902  N          ON
200906  Y          ON
200909  Y          ONThe SQL of the view object from this table/(entity object) is:
SELECT Terms.TERM
FROM TERMS Terms
WHERE AVAILABLE = 'Y' AND SWITCHED = 'ON'I am able to drag the selected two rows from the data control palette. But it is just a table. What I need is to ask the user to select one of them. What is the easiest way to achieve that?
Many thanks for your help!
Newman

Answer 1

Hi, Sireesha,
I almost succeed in the backing bean, except one last line when adding the new SelectItem into the list. Here is the code:
    private List<SelectItem> termList;
    public void setTermList(List<SelectItem> termList) {
        this.termList = termList;
    public List<SelectItem> getTermList() {
        return termList;
        FacesContext fc = FacesContext.getCurrentInstance();
        ValueBinding vb =    fc.getApplication().createValueBinding("#{data}");
        BindingContext bc = (BindingContext)vb.getValue(fc);
        DCDataControl dc = bc.findDataControl("ZBOVModuleDataControl");
        ApplicationModule am = (ApplicationModule)dc.getDataProvider();
        ZBOVModuleImpl zbovam = (ZBOVModuleImpl)am;
        TermsForStudentsImpl termsOpen = (TermsForStudentsImpl)zbovam.getTermsForStudents1();
        System.out.println("Number of rows: " + termsOpen.getEstimatedRowCount());
        long size = termsOpen.getEstimatedRowCount();
        for (int i = 0; i < size; i++) {
            Row currRow = termsOpen.getRowAtRangeIndex(i);
            String term = (String)currRow.getAttribute("Term");
            String termDesc = translateTerm(term);
            SelectItem selectItem = null;
            selectItem = new SelectItem(term, termDesc);
            // The code runs fine except when the one line below is uncommented
            //termList.add(selectItem);
            System.out.println(term + ": " + termDesc);
    public String translateTerm(String yyyymm) {
        String year = yyyymm.substring(0,4);
        String semester = null;
        String month = yyyymm.substring(4,6);
        if (month.equals("02")){
            semester = "Spring";
        } else if (month.equals("06")) {
            semester = "Summer";
        } else if (month.equals("09")) {
            semester = "Fall";
        return semester + " " + year;
    }The page in the front is blank except one line of static text, and nothing in the page binds to the termList in the backing bean yet. When the line {color:red}termList.add(selectItem);{color} is commented out, the page runs and the console prints out:
09/08/17 03:17:25 Number of rows: 3
09/08/17 03:17:25 200809: Fall 2008
09/08/17 03:17:25 200902: Spring 2009
09/08/17 03:17:25 200906: Summer 2009But uncommenting that line will cause a NullPointer error, and the error message says that the SelectTerm class can not be instantiated (I wrap round the long line of error message in the browser into several shorter lines):
javax.servlet.jsp.JspException: javax.faces.FacesException:
   javax.faces.FacesException: Can't instantiate class: 'zbov.viewcontroller.backing.student.SelectTerm'..
   class zbov.viewcontroller.backing.student.SelectTerm : java.lang.NullPointerExceptionI am stuck here. Do you have any idea what is wrong and how to get around this?
Thank you for helping.
Newman