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How do I resize the text inside my JScrollpane - JAVA

I'm currently learning more about Java. I'm working on creating a GUI which is able to 'translate' amino-acid characters into their 3-letter codes.
I've got everything working as intended, but I'm still struggling to understand how I can resize the text inside my JScrollpane to not exceed the width. (Example in picture)
Do I just need to change some settings or maybe add '\n's to fit the JTextArea? Here's the code:
Thanks in advance!
private void createGUI() {
Container window = this.getContentPane();
window.setLayout(new FlowLayout());
panel = new JPanel();
inputField = new JTextField();
startButton = new JButton("Convert to 3-letter code");
display = new JTextPane();
scroll = new JScrollPane(display);
//CUSTOMIZE GUI OBJECTS
inputField.setPreferredSize(new Dimension(200, 20));
display.setPreferredSize(new Dimension(400, 300));
startButton.addActionListener(this);
//SETTING UP TEXTAREA
display.setEditable(false);
scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
scroll.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
panel.setLayout(new BorderLayout());
panel.add(scroll, BorderLayout.CENTER);
//
window.add(inputField);
window.add(startButton);
window.add(panel);
}

Better use a JTextArea instead of a JScrollPane since the best that the JScrollPane can do is to dynamically resize (Dynamically Resize a JScrollPane?)

I changed JTextPane display to a JTextArea object and changed 'display.setLineWrap(true);'
This fixed the issue I was having with JTextPane.

To answer the question in the title: How do I resize the text inside my JScrollpane
Inside your scrollpane you have some JComponent. Either that JComponent is fully visible since it is smaller or equal to the JScrollpane's viewport. Or it is bigger, in which case the JScrollpane will start displaying scrollbars and the relevant part.
To resize the text you will just have to tell the JComponent inside the JScrollpane to display the text differently. Depending on the JComponent you use this method may vary. Here some examples:
In a JLabel and most other components, increase the font size (How to change the size of the font of a JLabel to take the maximum size)
In a JLabel, switch to a multiline label (Multiline text in JLabel)
In a JTextArea, turn on word wrapping and line wrapping
In a JEditorPane you can even use markup inside the document to use different font sizes at the same time

Scrollable JPanel without scrollBar

I have a problem with scroling JPanel,
I have a lot of labels and fields which are generated dynamicly, but my frame can't show it all.
My code:
JPanel showPanel = new JPanel();
JScrollPane scrollPane = new JScrollPane(showPanel);
add(scrollPane);
scrollPane.setBounds(0, 0, 400, 400);
scrollPane.setVisible(true);
scrollPane.add(Jbuttons);
And Im adding a lot of these buttons but my scrollPane won't show it.
I don't have any scrollBar, with text area I didn't have any problems.
Do you have any idea?

scrollPane.setBounds(0, 0, 400, 400); looks like you're using a null layout, don't this
scrollPane.add(Jbuttons); isn't how you should be adding content to the scroll pane, instead, add it to the showPanel which is already inside the JScrollPane. JScrollPane contains a single component, the JViewport, you can not "add" components to the JScrollPane, you must set the JViewports view to what you want shown and the manipulate this view
Take a look at How to Use Scroll Panes for more details

JTextArea keeps scrolling the main panel to the top

I have defined a JTextArea as follows:
JTextArea textArea = new JTextArea();
textArea.setText("Some text");
textArea.setEditable(true);
textArea.setLineWrap(true);
textArea.setWrapStyleWord(true);
JScrollPane scrollPane = new JScrollPane(textArea);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
scrollPane.getVerticalScrollBar().setAutoscrolls(false);
Now this component is one of a number of components which has been added to the main JPanel which is defined as follows:
JPanel panel = new JPanel();
panel.setName("Some name");
JScrollPane scrollPane = new JScrollPane();
scrollPane.setName("Some name");
scrollPane.getViewport().add(panel);
scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED);
scrollPane.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
scrollPane.getVerticalScrollBar().setAutoscrolls(false);
Now the JTextArea component appears near the bottom of the main panel and is partly hidden so you have to scroll down in order to see it all. But the problem I'm getting is that when I click on it, the main panel automatically scrolls back to the top again, hiding most of my JTextArea component again. So after clicking on it, the user has to then scroll down again in order to type something in.
But I can't work out why it's doing this. Is there a problem with using a JTextArea? If I use a JTextField then the problem doesn't occur.
Any help would be greatly appreciated!!

I think, replacing scrollPane.getViewport().add(panel) by scrollPane.getViewport().setView(panel) will solve the issue.

java Scrollbars not co-operating

Hello Im trying to create a JTextArea which once the data gets to large to hold the data the scroll bars can allow me to scroll however ATM there are no scroll bars just a little square box and the data is pushing the rest of the GUI up.
This is the code for the textArea and the scrollbars, p3 is the panel im trying to add the scrollbar and textArea too.
//TEXT AREA
final JTextArea dataTextField = new JTextArea();
dataTextField.setSize(750,200);
dataTextField.setLineWrap(true);
dataTextField.setEditable(false);
dataTextField.setVisible(true);
JScrollPane scroll = new JScrollPane (dataTextField);
scroll.setVerticalScrollBarPolicy(
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
scroll.setVisible(true);
p3.add(dataTextField);
p3.add(scroll);

//p3.add(dataTextField);
p3.add(scroll);
A swing component can only have a single parent. When you add the dataTextField to the panel you remove it from the scrollpane. Get rid of that line of code.

Do not use setSize (750, 200) on dataTextField. Just pass number of columns and rows to constructor of JTextArea.

How does one make an applet scroll?

I have been trying to use JScrollPane with my applet, but it doesn't work. I have a JPanel to which I add 20 buttons, and I want to be able to scroll up and down this JPanel. Instead, the scrollbars do not appear. When I use setPreferredSize they still did not appear even though only about 3 of the buttons are being displayed and the rest are cut off. If I do not use setPreferredSize, there might as well not be any scrollbars because I have to make the window big enough to see all of the buttons. If I try to make the scrollbars always visible, they appear but do nothing. I tried the exact same code with JFrame instead of Applet, and it works fine, but I need it to be an applet. Is JScrollPane incompatible with applets? (Note: I tried to use an outer JPanel and add the scrollable panel to it, but it changed nothing). Changing the layouts also doesn't fix the problem. I have attached a simplified version of my code, but it displays the same errors.
Here is the code I have:
JPanel scrollPanel = new JPanel();
scrollPanel.setLayout(new BoxLayout(scrollPanel, BoxLayout.PAGE_AXIS));
JScrollPane scroll = new JScrollPane(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
for (int i = 0; i < 20; i++) scrollPanel.add(new JButton("Button " + i));
add(scrollPanel);
validate();

You never all the panel to the scroll pane
You never add the scroll pane to the applet
The basic code should be:
JScrollPane scrollPane = new JScrollPane(...);
scrollPane.setViewportView( scrollPanel );
add( scrollPane );

You are adding components to a Panel so you shouldn't expect to see a scroll pane wihout showing the scrollpane. What you want to do is then add that panel to a scrollpane which would be added to ur main container.
From your code, i think your problem is
add(scrollPanel);
your should be doing this
add(scroll);`
This is because you only added the panel to the frame which does not contain any scrollpane. Since you have added the panel unto the scrollpane, you should add the scrollpane and not the panel to the main container.

It sounds like you are using Swing components (JScrollPane, JPanel, ...) in an AWT container (Applet). Try using JApplet instead.