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How can I add a scroll bar to a text area?

Please, anyone, tell me how to add the scrollbar to a JTextArea. I tried out many things. but still not able to get it. I copied some codes related to the text area.
public class main extends JPanel {
private JTextArea jcomp1;
public main() {
jcomp1 = new JTextArea(5, 5);
setPreferredSize(new Dimension(944, 574));
// setPreferredSize (new Dimension (1024, 1080));
setLayout(null);
//add components
add(jcomp1);
jcomp1.setBounds(110, 165, 330, 300);
}
public static void main(String[] args) {
JFrame frame = new JFrame("Paraphrasing Tool");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new main());
frame.pack();
frame.setVisible(true);
}
}

Oracle has a helpful tutorial, Creating a GUI With Swing. Skip the Netbeans section.
As Andrew said, you have to place the JTextArea inside of a JScrollPane, then place the JScrollPane inside of a JPanel with a Swing layout. I used a BorderLayout.
Here's the GUI after I typed some lines.
Here's the complete runnable code.
import java.awt.BorderLayout;
import java.awt.Insets;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class JTextAreaExample extends JPanel {
private static final long serialVersionUID = 1L;
private JTextArea jcomp1;
public JTextAreaExample() {
this.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
this.setLayout(new BorderLayout());
jcomp1 = new JTextArea(5, 30);
jcomp1.setMargin(new Insets(5, 5, 5, 5));
JScrollPane scrollPane = new JScrollPane(jcomp1);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
add(scrollPane);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame("Paraphrasing Tool");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new JTextAreaExample(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
});
}
}

Add the text area to (the viewport of) a JScrollPane. The easiest way is to add it in the constructor. Then add the scroll pane to a panel with a layout (in a GUI that uses layouts).

Java Swing CardLayout multiple files

I am trying to get this code to work, such that I have a cardlayout container and each panel be defined in its own class and actual file. This code is not 100% my own and is a modified version of my previous stuff by another Stack overflow user. It is more or less what I need, but I need it such that it isn't automated and I can write 15 different panels with decisions made inside each one. The Main and Arrow class was modified by said user, and Imagepanel is my attempt to write a class that will be accepted by the working part of the code. The issue is the Imagepanel I insert into the container will register as existing, but nothing shows up on the panel, it's blank. The commented out portion in ImagePanel is my code that I set on the back burner in favor of the established stuff previously used in the Arrow class.
Here is the Main class
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.*;
import javax.swing.*;
public class Main extends JPanel {
private Arrow arrow = new Arrow(); //creates a new Arrow object
public Main() {
JPanel btnPanel = new JPanel();
btnPanel.add(new JButton(new NextAction("Next")));
setLayout(new BorderLayout());
add(arrow, BorderLayout.NORTH);
add(btnPanel, BorderLayout.PAGE_END);
}
private class NextAction extends AbstractAction {
public NextAction(String name) {
super(name);
}
#Override
public void actionPerformed(ActionEvent e) {
arrow.next(); // *** call arrow's public next method that you created
// no need to make a new CardLayout instance
}
}
private static void createAndShowGui() {
Main mainPanel = new Main();
JFrame frame = new JFrame("Iowa Budget Simulation");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
Here is the Arrow class where the container is created
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagLayout;
import javax.swing.*;
class Arrow extends JPanel {
private static final long serialVersionUID = 1L;
private CardLayout cardLayout = new CardLayout(); // make me a field
private JPanel cardHolder = new JPanel(cardLayout); //creates a master JPanel
public Arrow() {
for (int i = 0; i < 5; i++) {
cardHolder.add(createCard(i), "card " + i);
}
ImagePanel pear = new ImagePanel();
cardHolder.add(pear, "Pear");
setLayout(new BorderLayout());
add(cardHolder, BorderLayout.NORTH);
}
// public method that other objects can call
public void next() {
cardLayout.next(cardHolder); // call next on the correct object
}
// simply creates a "pretty" new JPanel
private JComponent createCard(int i) {
JLabel label = new JLabel("Card " + i);
label.setFont(label.getFont().deriveFont(Font.BOLD, 50f));
float h = (float)Math.random();
Color c = Color.getHSBColor(h, 1f, 1f);
label.setForeground(c.darker());
JPanel panel = new JPanel(new GridBagLayout());
panel.add(label);
panel.setBorder(BorderFactory.createLineBorder(c.darker(), 20));
panel.setBackground(c.brighter().brighter());
panel.setPreferredSize(new Dimension(400, 300));
return panel;
}
Here is ImagePanel, my attempt at a 3rd, individual panel/class
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagLayout;
import javax.swing.*;
class ImagePanel extends JPanel {
private static final long serialVersionUID = 1L;
private String imgString;
private JLabel imgLabel;
public JComponent ImagePanel() {
/*
setName("Pear");
JLabel john = new JLabel("Pear");
float h = (float)Math.random();
Color c = Color.getHSBColor(h, 1f, 1f);
john.setForeground(c.darker());
JPanel panel = new JPanel(new GridBagLayout());
panel.add(john);
panel.setBorder(BorderFactory.createLineBorder(c.darker(), 20));
panel.setBackground(c.brighter().brighter());
// Ensure size is correct even before any image is loaded.
setPreferredSize(new Dimension(400, 300));
return panel;
*/
JLabel label = new JLabel("Pear");
label.setFont(label.getFont().deriveFont(Font.BOLD, 50f));
float h = (float)Math.random();
Color c = Color.getHSBColor(h, 1f, 1f);
label.setForeground(c.darker());
JPanel panel = new JPanel(new GridBagLayout());
panel.add(label);
panel.setBorder(BorderFactory.createLineBorder(c.darker(), 20));
panel.setBackground(c.brighter().brighter());
panel.setPreferredSize(new Dimension(400, 300));
return panel;
}
There is no error to post, it simply displays a blank panel. Thank you for any assistance I might receive, and I apologize in advance as I am learning Java Swing GUI through YouTube and stack overflow.

public JComponent ImagePanel() { isn't a constructor, it's a method, to make it work in your code you would have to change ImagePanel pear = new ImagePanel(); to JComponent pear = new ImagePanel().ImagePanel();, but frankly that just doesn't make much sense.
Instead, change public JComponent ImagePanel() { to public ImagePanel() {, now it's the class's constructor
Next, change...
JPanel panel = new JPanel(new GridBagLayout());
panel.add(label);
panel.setBorder(BorderFactory.createLineBorder(c.darker(), 20));
panel.setBackground(c.brighter().brighter());
panel.setPreferredSize(new Dimension(400, 300));
return panel;
to
setLayout(new GridBagLayout());
add(label);
setBorder(BorderFactory.createLineBorder(c.darker(), 20));
setBackground(c.brighter().brighter());
//panel.setPreferredSize(new Dimension(400, 300));
//return panel;
Don't get me started on why setPreferredSize is a bad idea
Now you can simply use
ImagePanel pear = new ImagePanel();
cardHolder.add(pear, "Pear");

Set JTextFields and JButtons position in CardLayout

This is a java template i found about Card Layout
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Main {
private static final String CARD_JBUTTON = "Card JButton";
private static final String CARD_JTEXTFIELD = "Card JTextField";
private static final String CARD_JRADIOBUTTON = "Card JRadioButton";
private static void createAndShowGUI()
{
JFrame frame = new JFrame("Card Layout Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
// This JPanel is the base for CardLayout for other JPanels.
final JPanel contentPane = new JPanel();
contentPane.setLayout(new CardLayout(200, 200));
/* Here we be making objects of the Window Series classes
* so that, each one of them can be added to the JPanel
* having CardLayout.
*/
Window1 win1 = new Window1();
contentPane.add(win1, CARD_JBUTTON);
Window2 win2 = new Window2();
contentPane.add(win2, CARD_JTEXTFIELD);
Window3 win3 = new Window3();
contentPane.add(win3, CARD_JRADIOBUTTON);
/* We need two JButtons to go to the next Card
* or come back to the previous Card, as and when
* desired by the User.
*/
JPanel buttonPanel = new JPanel();
final JButton previousButton = new JButton("PREVIOUS");
previousButton.setBackground(Color.BLACK);
previousButton.setForeground(Color.WHITE);
final JButton nextButton = new JButton("NEXT");
nextButton.setBackground(Color.RED);
nextButton.setForeground(Color.WHITE);
buttonPanel.add(previousButton);
buttonPanel.add(nextButton);
/* Adding the ActionListeners to the JButton,
* so that the user can see the next Card or
* come back to the previous Card, as desired.
*/
previousButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
CardLayout cardLayout = (CardLayout) contentPane.getLayout();
cardLayout.previous(contentPane);
}
});
nextButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
CardLayout cardLayout = (CardLayout) contentPane.getLayout();
cardLayout.next(contentPane);
}
});
// Adding the contentPane (JPanel) and buttonPanel to JFrame.
frame.add(contentPane, BorderLayout.CENTER);
frame.add(buttonPanel, BorderLayout.PAGE_END);
frame.pack();
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
}
And this is my Window1.java
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
class Window1 extends JPanel
{
/*
* Here this is our first Card of CardLayout, which will
* be added to the contentPane object of JPanel, which
* has the LayoutManager set to CardLayout.
* This card consists of Two JButtons.
*/
private ActionListener action;
public Window1()
{
init();
}
private void init()
{
final JButton clickButton = new JButton("Click ME");
final JButton dontClickButton = new JButton("DON\'T CLICK ME");
final JTextField title = new JTextField(12);
action = new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
if (ae.getSource() == clickButton)
{
String myString = title.getText();
System.out.println(myString);
}
else if (ae.getSource() == dontClickButton)
{
JOptionPane.showMessageDialog(null, "I told you not to click me!"
, "Wrong Button", JOptionPane.PLAIN_MESSAGE);
}
}
};
clickButton.addActionListener(action);
dontClickButton.addActionListener(action);
add(clickButton);
add(dontClickButton);
add(title);
}
}
Now my problem is that how do i set the position of the textfields and buttons in Window1?
With this code they are set in the center of the view aligned horizontally.
I tried to use title.setLocation(5,5); but it's not working. Any suggestions?

Now my problem is that how do i set the position of the textfields and buttons in Window1?
Rows like Jlabel - JTextField then new row ,and in the end of the page the button
The thing is you're not using any layout managers. The default layout manager for JPanel is FlowLayout, which will do exactly what you're experiencing (horizontal layout of the components).
Getting vertical alignment could be achieved by using different layout managers. You could use a GridBagLayout for all the component, or a GridLayout, or you could nest JPanel with different layout managers. The possibilities are endless. It just comes down to the exact look you want.
See Laying out Components Within a Container to learn how to use different layout managers. I'll give you an example, but don't let it stop you from looking at the tutorials. You need to learn them.
Also besides just positioning of the components layout managers use dynamic sizing either by respecting the preferred of components are not respecting them. You can see a picture in this answer of some of the layout managers that do and don't respect preferred sizes.
import java.awt.FlowLayout;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class LayoutManagers extends JPanel{
public LayoutManagers() {
JLabel label = new JLabel("Text Field");
JTextField textField = new JTextField(20);
JRadioButton rb1 = new JRadioButton("Radio 1");
JRadioButton rb2 = new JRadioButton("Radio 2");
JButton button = new JButton("Button");
JPanel panel1 = new JPanel();
panel1.add(label);
panel1.add(textField);
JPanel panel2 = new JPanel();
panel2.add(rb1);
panel2.add(rb2);
JPanel panel3 = new JPanel(new FlowLayout(FlowLayout.TRAILING));
panel3.add(button);
JPanel panel4 = new JPanel(new GridLayout(3, 1));
panel4.add(panel1);
panel4.add(panel2);
panel4.add(panel3);
setLayout(new GridBagLayout());
add(panel4);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable(){
public void run() {
JFrame frame = new JFrame();
frame.add(new LayoutManagers());
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
});
}
}

JPanel in the middle of the frame

I'm trying to put my jpanel in the middle of the frame... so when the user try to change the size of the window frame, it remain in the middle...
something like this:
so if i change size it have to remain in the middle:
i Tried to change the layout of my contentPane with the BorderLayout and put my jpanel in the center position... but when i change size of my frame the panel go in the top left corner.
In my windows builder the situation is this:
my jpanel have to work exactly how works the redbox. i tried everything but the result is everytime the same:
this is my code:
package StudApp;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JMenuBar;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JTextPane;
import javax.swing.JLabel;
import java.awt.Font;
import javax.swing.SwingConstants;
import java.awt.Color;
import javax.swing.JTextArea;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class StudApp {
private JFrame frame;
private JPanel homeFirstRun;
private ArrayList<Corso> corsi = new ArrayList<Corso>();
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
new StudApp();
}
});
}
/**
* Create the frame.
*/
public StudApp() {
frame = new JFrame("Student Note");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(100, 100, 450, 300);
JMenuBar menuBar = new JMenuBar();
frame.setJMenuBar(menuBar);
JMenu menuHelp = new JMenu("Help");
menuBar.add(menuHelp);
JMenuItem menuIstrStud = new JMenuItem("Intructions Student Note");
menuIstrStud.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
frame.remove(homeFirstRun);
frame.revalidate();
frame.repaint();
homeFirstRun = null;
}
});
menuHelp.add(menuIstrStud);
homeFirstRun = new JPanel();
homeFirstRun.setBorder(new EmptyBorder(5, 5, 5, 5));
homeFirstRun.setLayout(null);
frame.getContentPane().add(homeFirstRun);
JLabel welcomeMessage = new JLabel("Welcome to Student Note");
welcomeMessage.setBounds(5, 5, 424, 18);
welcomeMessage.setForeground(Color.DARK_GRAY);
welcomeMessage.setHorizontalAlignment(SwingConstants.CENTER);
welcomeMessage.setFont(new Font("Verdana", Font.BOLD, 14));
homeFirstRun.add(welcomeMessage);
JTextArea welcomeTextArea = new JTextArea();
welcomeTextArea.setFont(new Font("Verdana", Font.PLAIN, 13));
welcomeTextArea.setText(" I think it's your first time here.\n\n"
+ " So the first step is to create a new course to\n insert your grades.\n\n"
+ " If you want my advice, read how this program\n works in the help section (it is very simple),\n "
+ "just 2 minutes ... believe me");
welcomeTextArea.setEditable(false);
welcomeTextArea.setBounds(27, 34, 381, 184);
homeFirstRun.add(welcomeTextArea);
frame.setVisible(true);
}
}

There are several ways to do this, but one of the easiest is to give the contentPane a GridBagLayout, and then add your JPanel of interest with no GridBagConstraints. If the JPanel of interest is the only thing added to this container, this will then place that JPanel into a central position.
e.g.,
import java.awt.*;
import javax.swing.*;
public class CentralPanel {
private static void createAndShowGui() {
JFrame frame = new JFrame("CentralPanel");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(new MyContentPane());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class MyContentPane extends JPanel {
private static final int PREF_W = 700;
private static final int PREF_H = 550;
public MyContentPane() {
setLayout(new GridBagLayout());
add(new JPanelOfInterest());
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
}
class JPanelOfInterest extends JPanel {
private static final int PREF_W = 400;
private static final int PREF_H = PREF_W;
public JPanelOfInterest() {
setBorder(BorderFactory.createTitledBorder("JPanel of Interest"));
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
}

Set size of jpanel on a JFrame explicitly

I have JPanel with a border, the problem is that when I add the panel on the JFrame it takes the panel size although I set the preferred size for the panel using setPreferredSize. The layout of the frame is 'BoxLayout' and here's the code:
public class ActionForm extends JFrame {
JPanel namePanel;
JPanel descPanel;
JLabel actionName;
JLabel nameLabel;
JTextField nameTextField, descTextField;
FlowLayout toolBarLayout = new FlowLayout();
public ActionForm() {
this.setLayout(new BoxLayout(this.getContentPane(), BoxLayout.Y_AXIS));
TitledBorder nameBorder= BorderFactory.createTitledBorder(
"Change Description");
nameBorder.setTitleJustification(TitledBorder.LEFT);
namePanel = new JPanel(toolBarLayout);
namePanel.setPreferredSize(new Dimension(150, 150));
nameLabel = new JLabel("ButtonName");
nameTextField = new JTextField("Action's Name", 50);
namePanel.add(nameLabel);
namePanel.add(nameTextField);
namePanel.setBorder(nameBorder);
namePanel.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
this.add(namePanel);
}
public static void main(String[] args) {
ActionForm form = new ActionForm();
form.setVisible(true);
form.setSize(970, 500);
form.setResizable(false);
}
}
Why the size of the panel doesn't change?

BoxLayout accepting Min/Max/preferredSize that came from JComponents layed by this LayoutManager
(I'm don't want to comment something, because my answer will be so long) please to compare your code with this code example, there are implemented all good (required and important) Swing rulles
for example
import java.awt.ComponentOrientation;
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.border.TitledBorder;
public class ActionForm {
private static final long serialVersionUID = 1L;
private JFrame frame;
private JPanel namePanel;
private JLabel nameLabel;
private JTextField nameTextField;
private FlowLayout toolBarLayout = new FlowLayout();
public ActionForm() {
TitledBorder nameBorder = BorderFactory.createTitledBorder(
"Change Description");
nameBorder.setTitleJustification(TitledBorder.LEFT);
namePanel = new JPanel(toolBarLayout);
namePanel.setPreferredSize(new Dimension(150, 150));// hardCoded sizing
namePanel.setMaximumSize(new Dimension(250, 150)); // hardCoded sizing
namePanel.setMinimumSize(new Dimension(150, 150)); // hardCoded sizing
nameLabel = new JLabel("ButtonName");
nameTextField = new JTextField("Action's Name", 10);
namePanel.add(nameLabel);
namePanel.add(nameTextField);
namePanel.setBorder(nameBorder);
namePanel.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
frame = new JFrame("Mix / Max / PreferredSize for BoxLayout");
frame.getContentPane().setLayout(new BoxLayout(frame.getContentPane(),
BoxLayout.Y_AXIS)); // otherwise nice exceptions java.awt.AWTError:
// BoxLayout can't be shared
frame.add(namePanel);
frame.setPreferredSize(new Dimension(970, 500));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
ActionForm form = new ActionForm();
}
});
}
}