JList/ListModel getElements not working

Question

I am having problems with grabbing all the elements of a ListModel, when i try to write the strings to file they output something like the following:

[Ljava.lang.String;@79b43f[Ljava.lang.String;@79b43f

So what am i doing wrong? Here is the code that is causing the grief:

for (int i = 0; i < listModel.getSize(); i++)
        {
            String[] temp = listModel.getElementAt(i).toString().split("-");
            bw.write(temp[0]);
            bw.write(temp[1]);

            System.out.println(temp[0]);
        }

bw is a bufferedWriter and listModel is a custom list model that I have made.. You may notice I have split the string,, this is because i want to extract two different values from each list row, I have simply done setText(text + "-" + text) in my customCellRenderer implementation in order to enable me to use the "-" char as a delim to extract the two values

public class CustomCellRenderer extends JLabel
implements ListCellRenderer
{
    JLabel left, right;
}

public CustomCellRenderer() 
{
    setOpaque(true);
}

@Override
public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus)
{        
    String leftData = ((String[])value)[0];
    String rightData = ((String[])value)[1];

    // simply will not function how i want it to.. GRR
    leftData = String.format("%-50s", leftData);


    setText(leftData + "-   " + rightData);

    if (isSelected)
    {
        setBackground(list.getSelectionBackground());
        setForeground(list.getSelectionForeground());
        setBackground(list.getSelectionBackground());
        setForeground(list.getSelectionForeground());
    }
    else
    {
        setBackground(list.getBackground());
        setForeground(list.getForeground());
        setBackground(list.getBackground());
        setForeground(list.getForeground());
    }

    return this;
    }
}

Answer 1

What you've posted isn't the ListModel - it's the ListCellRenderer. But this does reinforce the idea that each item in your JList is a String[] - e.g. you are casting each value in the JList to a String[] for rendering.

String leftData = ((String[])value)[0];
String rightData = ((String[])value)[1];

It appears that there is some confusion as to where the the ListModel is being populated. Your post/code suggests that you think it is being populated in the ListCellRenderer - this is not the case. It is only working out how to display the values already in the ListModel.

So, a quick fix could be in the 'code that's giving you grief':

String[] temp = (String[]) listModel.getElementAt(i);
bw.write(temp[0]);
bw.write(temp[1]);

However, I wouldn't really encourage this, as you'll have unchecked class casts.

Instead, I would suggest you consider why you are populating the ListModel with String[] in the first place? e.g. are you constructing the JList as follows:

JList myList = new JList(new String[]{"A","B"}, new String[]{"C","D"});

Answer 2

It seems in your custom list model, listModel.getElementAt(i) returns an array. Please check it and post your custom list model here if you need further assistance.