JList列表项已压缩

我的JList工作了,但只有第一个列表项的大小合适。下面的一切都被压扁了。我已经搜索了所有的StackOverflow,但没有找到太多(不过,要让它正常工作,只需要StackOverload)

package networks;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.util.ArrayList;
import java.util.Random;
import javax.swing.*;

/**
 *
 * @author Matthew
 */
public class Networks extends JFrame implements ActionListener {

    private static JPanel container = new JPanel();
    private static JPanel graphPanel = new JPanel();
    private static JPanel content = new JPanel();
    private static JPanel buttons = new JPanel();
    private static Graphics2D g;
    private static JButton read = new JButton("Read");
    private static JButton breadth = new JButton("Breadth");
    private static JButton depth = new JButton("Depth");
    private String[] listModel = new String[10];
    private static JScrollPane scroller = new JScrollPane();
    private JList lists;

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Networks networks = new Networks();
        networks.setVisible(true);
    }

    public Networks() {
        super("Station Networks");
        //Set up window and frames, buttons and lists
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        container.setLayout(new BoxLayout(container, BoxLayout.Y_AXIS));
        content.setLayout(new BoxLayout(content, BoxLayout.Y_AXIS));
        content.setPreferredSize(new Dimension(260,300));
        buttons.setLayout(new BoxLayout(buttons, BoxLayout.X_AXIS));
        graphPanel.setPreferredSize(new Dimension(255,255));

        //Add default value, tester
        listModel[0] = "The station list is currently empty";
        lists = new JList(listModel);
        lists.setVisibleRowCount(5);
        scroller.setViewportView(lists);
        BufferedImage im = new BufferedImage(255,255,BufferedImage.TYPE_INT_RGB);
        g = im.createGraphics();

        //add listeners
        read.addActionListener(this);
        breadth.addActionListener(this);
        depth.addActionListener(this);

        //put it all togethe
        content.add(graphPanel);
        content.add(new Label("List"));
        content.add(scroller);
        buttons.add(read);
        buttons.add(breadth);
        buttons.add(depth);
        container.add(content);
        container.add(buttons);
        add(container);
        pack();
        setVisible(true);
    }

我有一个稍后添加列表项的功能。这些物品被压扁了。是否有方法设置列表项的大小?