Java Swing DefaultListModel包含存储更多信息

Question

I created a class to store two properties

public class MailEntry {
    private String mail;
    private MailFormat format; // this is an enum

    public MailEntry(String mail, MailFormat format) {
        this.mail = mail;
        this.format = format;
    }

    public String getMail() {
        return mail;
    }

    public MailFormat getFormat() {
        return format;
    }
}

the JList created for me by the Netbeans GUI is declared by

    private javax.swing.JList<String> jList1;

and initialized a DefaultListModel

private DefaultListModel<MailEntry> listModel = new DefaultListModel<>();

and set this as a model

jList1.setModel(listModel);

But what I get is

 error: incompatible types: DefaultListModel<MailEntry> cannot be converted to ListModel<String>
    jList1.setModel(listModel);

It seems that jList expects a model of Strings. But I'd like to store more item-specific information, which will be accessible through the GUI.

How can I work it around?

Answer 1

The problem is you've decleared jList1 as...

private javax.swing.JList<String> jList1;

but you're declaring the model as...

DefaultListModel<MailEntry> listModel = new DefaultListModel<>();

MailEntry and String are not compatible classes and the JList is expecting a ListModel<String> based model.

You need to change the JList declaration to support your model, something like

private javax.swing.JList<MailEntry> jList1;

Since you're using Netbean's form editor (don't get me started), you will need to select the JList from the "Navigator"

Select the "Code" tab from the "Properties" tab...

and change the Type Parameters to meet your requirements

Answer 2

private DefaultListModel<MailEntry> listModel = new DefaultListModel<>();

Should be:

private DefaultListModel<MailEntry> listModel = new DefaultListModel<MailEntry>();

And then when you create the JList you should be using:

JList<MailEntry> list = new Jlist<MailEntry>();

So everything should be consistent.

Note you should also need to create a custom renderer to display the data. The default renderer only uses the toString() value of the class. You can read the section from the Swing tutorial on How to Use Lists for more information and examples.

The other option is to just implement a toString() method in your class.