java jscrollpane參數,Java JScrollPane

I'm trying to add a Vertical scrolling my java programs textarea. I am using this code to create my JScrollPane:

console = my textarea.

I am also Declaring JScrollPane vertical;

vertical = new JScrollPane(console);

vertical.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

vertical.setVisible(true);

this.add(vertical);

EDIT:

View of program:

I'm new to Java but shouldn't that work and add a Vertical scroll bar to my textarea

What am I doing wrong?

Thanks for any help.

解決方案

Here is an example:

import java.awt.Dimension;

import javax.swing.*;

public class ScrolledPane extends JPanel

{

private JScrollPane vertical;

private JTextArea console;

public ScrolledPane()

{

setPreferredSize(new Dimension(200, 250));

console = new JTextArea(15, 15);

vertical = new JScrollPane(console);

vertical.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

add(vertical);

}

public static void main( String args[] )

{

new JFrame()

{{

getContentPane().add(new ScrolledPane());

pack();

setVisible(true);

}};

}

}