This is a study of getting scroll bars to work in Java's Swing API, using a JScrollPane

JScrollPaneStudy.java

import java.awt.Dimension;
import java.awt.FlowLayout;

import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;

/**
 * This class is a study in learning how to get scroll bars to work for a JList using a JScrollPane.
 * 
 * The numbers have been "fudged" to get things to work.  But it does work.  
 * 
 * @author kaydell
 *
 */
public class JScrollPaneStudy extends JFrame {
  
	public JScrollPaneStudy() {
		
		// use a FlowLayout LayoutManager because it is just simple
		setLayout(new FlowLayout());
		
		// create the top left JList
		String[] array2 = new String[50];
		for (int i = 0; i < 50; i++) {
			array2[i] = Integer.toString(i);
		}
		JList<String> topLeftList = new JList<String>(array2);
		// topLeftList.addListSelectionListener(this);
		JScrollPane jScrollPane = new JScrollPane(topLeftList);
		
		// usually, we want to set the preferred sizes of things.  There
		// is also size, minimum size, and maximum size
		topLeftList.setPreferredSize(new Dimension(300, 2000)); // make room in the JList for many lines.  This should really grow as items are added
		jScrollPane.setPreferredSize(new Dimension(300, 300));
		
		// add the scroll pane to this window
		add(jScrollPane);
		
		// finish initializing this window
		pack(); // size this window
		setLocationRelativeTo(null); // center this window
	}
	
	public static void main(String[] args) {
		SwingUtilities.invokeLater(new Runnable() {
			@Override
			public void run() {
				new JScrollPaneStudy().setVisible(true);
			}
		});
	}

}