How do I change the size of a JScrollPane in java

Question

I have never used one of these before.I have only used normal JOptionPane boxes.This is what I have at the moment:

JOptionPane.showMessageDialog(null,new JScrollPane(new JList(uniqueWords.toArray())),"Unique Words",1);

where uniqueWords is an array list.The problem is the length of the dialog box is tiny.You can only see one line on screen at a time.How can I make it display more at a time. Also is it possible to get rid of these notes and what causes them

Note: Files.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

EDIT: I changed my code to this

JScrollPane jspane = new JScrollPane(new JList(uniqueWords.toArray()));
    Dimension size = new Dimension(1000,1000);
    jspane.setMinimumSize(size);
    JOptionPane.showMessageDialog(null,jspane,"Unique Words",1);

but it is still displaying the same dialog box

Answer 1

"How can I make it display more at a time"

You can just override the getPreferredSize of the JScrollPane

import java.awt.Dimension;
import java.util.*;
import javax.swing.*;

public class Test3 {


    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable(){
            public void run() {
                List<String> list = new ArrayList<>();
                for (int i = 0; i < 30; i++) {
                    list.add("Hello, World " + i);
                }
                JScrollPane pane = new JScrollPane(new JList(list.toArray())) {
                    @Override
                    public Dimension getPreferredSize() {
                        return new Dimension(200, 250);
                    }
                };
                JOptionPane.showMessageDialog(null, pane);
            }
        });
    }
}

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"Also is it possible to get rid of these notes and what causes them"

You should do what it says and recompile with -XLint and it will show you details of the warnings