Java Swing - 如何更改JScrollPane的大小

import java.awt.Dimension;
import java.util.ArrayList;
import java.util.List;

import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;

public class Main {
  public static void main(String[] args) {
    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);
  }
}