How to set multiple items as selected in JList using setSelectedValue?

Question

I have a jList that is populated dynamically by adding to the underlying listModel. Now if I have three Strings whose value I know and I do

for(i=0;i<3;i++){
    jList.setSelectedValue(obj[i],true);//true is for shouldScroll or not
}

only the last item appears to be selected...If this can't be done and I have to set the selection from the underlying model how should I go about it???

Also please note the jList has selection mode:

  jList.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);

Thanks in Advance

Solution 1

Although StanislasV answer is perfectly valid, i would prefer to avoid adding one selection interval to another. Instead, you should prefer to call the JList associated ListSelectionModel#setSelectionInterval(int, int) method like this :

jList.getSelectionModel().setSelectionInterval(0, 3)

If you want your list selection to be disjoint, you'll moreover have to write your own ListSelectionModel.

Solution 2

Note that all xxSelectedValue methods are convenience wrapper methods around the selectionModel (which supports index-based selection access only) on the JList. Setting multiple selections per value is not supported. If you really want it, you'll have to implement a convenience method yourself. Basically, you'll have to loop over the model's elements until you find the corresponding indices and call the index-based methods, something like:

public void setSelectedValues(JList list, Object... values) {
    list.clearSelection();
    for (Object value : values) {
        int index = getIndex(list.getModel(), value);
        if (index >=0) {
            list.addSelectionInterval(index, index);
        }
    }
    list.ensureIndexIsVisible(list.getSelectedIndex());
}

public int getIndex(ListModel model, Object value) {
    if (value == null) return -1;
    if (model instanceof DefaultListModel) {
        return ((DefaultListModel) model).indexOf(value);
    }
    for (int i = 0; i < model.getSize(); i++) {
        if (value.equals(model.getElementAt(i))) return i;
    }
    return -1;
}

Solution 3

jList.addSelectionInterval(0,2);

Comments

[kleopatra]

-1 that's simply wrong - addSelectionInterval is the method intended to .. well .. adding something to the selection. The exact outcome depends on the SelectionMode

[mre]

+1 addSelectionInterval does the trick. This should be the accepted accept!!!! :D

[mre]

+1 spot-on with addSelectionInterval, but in order for this to be a truly useful answer, an explanation is required.

[PhoneixS]

Get in mind that DefaultListModel.indexOf(value) already do a linear search so it's the same using indexOf than the for version (the same efficiency although more readable).

[kleopatra]

@PhoneixS it's an implementation detail that we can't know :)

[PhoneixS]

We can really know, at least with oracle and OpenJDK as we can see the source code (like I have done). It's the good thing about OpenSource :D

[kleopatra]

@PhoneixS yeah, we could read - but we can't know for sure because the implementation isn't part of the specification and could change without notice :) Don't rely on implementation details, never-ever ...

[PhoneixS]

@kleopatra I totally agree, but it's something to get in mind so you don't think that indexOf is somewhat magic.