JList在Java中显示空行

Question

I have a following array:

static String[] nameData = new String[100];

And a JList , with displays the array's contents:

rightPanel.add(Box.createRigidArea(new Dimension(20, 20)));
final JList list = new JList(nameData);
list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
list.setLayoutOrientation(JList.VERTICAL);
list.setVisibleRowCount(-1);
JScrollPane listScroller = new JScrollPane(list);
listScroller.setPreferredSize(new Dimension(250, 80));
listScroller.setAlignmentX(LEFT_ALIGNMENT);
rightPanel.add(listScroller);

But when for example only first slot in the array are filled and rest are with the value null, JList still displays them as an empty line and lets you select it (I have added an image below).

This is how a 7th element in array would be selected, although I would like the JList only to display elements that have a value besides null.

Answer 1

I think you need to read tutorial for JList .

You add new String[100] to your list, because of it has 100 values. You can filter your array before adding to JList or ListModel for getting only notNull and notEmpty values.

Answer 2

If you dont want to display null/empty values, you can either create another String by removing null entries or the more preferable option, use a DefaultListModel

Create another String

int i=0;
for(i=0;i<nameData.length;i++){
    if(nameData[i]==null) break;   // count number of elements
}
String[] myString = new String[i];  // declare string
for(i=0;i<myString.length;i++){
    myString[i] = nameData[i];      // copy
}
// Create JList
final JList list = new JList(nameData);

Or

Use DefaultListModel

DefaultListModel model = new DefaultListModel();
for(int i=0;i<nameData.length;i++){
    if(nameData[i]==null) break;
    model.addElement(nameData[i]);   // build defaultlistmodel
}
final JList list = new JList();
list.setModel(model);

Answer 3

那是因为您使用100个null元素组成的数组，所以可以使用Vector代替