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How to set scroll to the top - JPanel that has multiple JTextareas inside Jscrollpane

I have a JPanel in a JScrollPane.
The JPanel contains multiple JTextAreas vertically.
I like to keep the scroll of the scrollpane to the top whenever the page is refreshed.
Currently, the scroll always starts from the bottom.
this is my current code and it doesn't work..
panel.invalidate();
panel.revalidate();
panel.repaint();
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
((JPanel) panel).setLocation(new Point(0, 0));
}
});
I've also tried adding this code below to scrollpane, but it doesn't work..
scrollPanel.getViewport().setViewPosition( new Point(0, 0) );
I've looked into other stackoverflow questions and they use Jtextarea inside Jscrollpane (they solved it using setCaretPosition(0), however I can't use the same function to the panel). In my case, there is an extra layer.
How can I solve this..?
EDIT**
Based on advice from Pavlo Viazovskyy, I've also tried this below and it still doesn't work for me.. :(
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
scrollPane.getVerticalScrollBar().setValue(0);
}
});

Thank you very much for all the comments.
sorry I didn't give a full proper example in the question as there were too many different classes involved..
In my case, textareas inside Panel inside ScrollPane, I made the scroll to the top by default by using setViewPosition method to scrollPane in the invokelater method.
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
scrollPane.getViewport().setViewPosition( new Point(0, 0) );
}
});

For when you don't have direct access to the JScrollPane, you can simply use JComponent#scrollRectToVisible
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
public class ScrollTest {
public static void main(String[] args) {
new ScrollTest();
}
public ScrollTest() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame("Test");
frame.add(new JScrollPane(new BigPane()));
frame.setSize(200, 200);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class BigPane extends JPanel {
public BigPane() {
setLayout(new BorderLayout());
JButton scroll = new JButton("Scroll to top");
add(scroll, BorderLayout.SOUTH);
scroll.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
scrollRectToVisible(new Rectangle(0, 0, 1, 1));
}
});
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
}
}
Yes, you could walk the component hierarchy till you found a JViewport, but this method does it for you.
Just remember though, the Rectangle is relative to the component which called the method, so if I used the JButton instead, it would try and make the JButton visible, not the panel

Java : using graphics component within an action listener

I've made a JFrame with Diferent JButtons and i'd like to get an image from another class. Any ideas? Or how draw on the same class but on the action performed?
Because it doesnt let me to do any drawings...my complier always gives me error messages
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import javax.swing.*;
public class red extends JFrame {
public JButton b;
public JButton b1;
public JButton b2;
public JButton b3;
public JButton b4;
public static Image p;
public static Graphics g;
public red() throws IOException {
gui1 x = new gui1();
setTitle(" ");
setSize(1200,700);
setLayout(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);
b= new JButton("click");
b1= new JButton();
b.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e0){
b1.setBounds(0, 0, 200, 200);
b.show(false);
add(x);
}
});
b.setBounds(0, 0, 100, 100);
add(b1);
add(b);
setVisible(true);
}
public static void main(String[] args) throws IOException {
red k = new red();
}
}
import java.awt.*;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
public class gui1 extends Canvas {
public static Image p;
public void paint(Graphics g){
g.drawImage(p, 700, 200, 100, 100, this);
}
{
try {
p= ImageIO.read(new File("Lighthouse.jpg"));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

Phew! I see A LOT of errors in your code (even after I corrected the compilation errors):
You're not following the Java naming conventions:
Class names should be nouns, in mixed case with the first letter of each internal word capitalized
while red is a noun it should be more descriptive and be capitalized. The same goes for gui1
You're extending JFrame which in plain english would say: red is a JFrame, you should really avoid this and create your GUI based on JPanels instead... see Java Swing using extends JFrame vs callint it inside of class
You're setting size (a REAAAAAAALLY big one window for the JButton sizes you're using), instead use pack()
You're using null-layout, while pixel-perfect GUIs might seem like the easiest way to create complex GUIs for Swing newbies, the more you use them the more problems related to this you'll find in the future, they are hard to maintain and cause random problems, they don't resize, etc. Please read Null layout is evil and Why is it frowned upon to use a null layout in Swing? for more information about why you should avoid its use and why you should change your GUI to work with Layout Managers along with Empty Borders for extra spacing between components.
You're making use of a deprecated method JFrame#show() you should be using JFrame#setVisible(...) instead.
Related to point #4, you shouldn't be calling setBounds(...) method, but let that calculations to the layout managers.
You're not placing your program on the Event Dispatch Thread (EDT), Swing is not thread safe, you can fix this by changing your main() method as follows:
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
//Your constructor here
}
});
}
You're mixing AWT and Swing components, instead of using AWT's Canvas use Swing's JPanel which has more functionality and support.
Images will become embedded resources once they're packaged in a JAR file, so it's wise to start treating them as if they already were, not as external files as shown in the embedded-resource tag.
Once you change from Canvas to JPanel you should override its paintComponent(...) method and not paint(...) and call it's super.paintComponent(g) method as the first line, also don't forget to add the #Overrides annotation. See the tutorial on Swing custom painting.
You're abusing the use of static keyword, see how does the static keyword works?
After seeing all the above errors I recommend you to go back and Learn the basics of the language before starting with a graphical environment which will only add more difficulty to your learning.
From what I understand you want to draw an image on a button click, if that's the case then you can wrap your image in a JLabel and add that JLabel to a JPanel which then is added to a parent JPanel which is later added to the JFrame:
As you can see in the GIF above, the icon is displayed after user presses the button.
Obviously this can be improved for the GUI to be more "attractive" with combinations of layout managers and empty borders as stated before.
This was done with the following code:
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BoxLayout;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class ImageDrawingFromOneClassToAnother {
private JFrame frame;
private JPanel pane;
private JPanel leftPane;
private JPanel rightPane;
private ImageIcon icon;
private JButton button;
private JLabel label;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new ImageDrawingFromOneClassToAnother().createAndShowGui();
}
});
}
public void createAndShowGui() {
frame = new JFrame(getClass().getSimpleName());
icon = new ImageIcon(this.getClass().getResource("king.png")); //Read images as if they were already embedded resources
button = new JButton("Draw image");
label = new JLabel(""); //Create an empty label
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
label.setIcon(icon); //On button click, we set the icon for the empty label
}
});
pane = new JPanel() {
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 200); //Set a size for the main panel
}
};
pane.setLayout(new GridLayout(1, 2)); //The main panel
leftPane = new JPanel(); //The button panel
leftPane.setLayout(new BoxLayout(leftPane, BoxLayout.PAGE_AXIS));
leftPane.add(button);
rightPane = new JPanel(); //The panel where the image will be drawn
rightPane.add(label);
//We add both (button and image) panels to the main panel
pane.add(leftPane);
pane.add(rightPane);
frame.add(pane); //Add the main panel to the frame
frame.pack(); //Calculate its preferred size
frame.setVisible(true); //Set it to be visible
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

Swing code compilation error "missing ;"

How do I solve this compilation error? Note that I'm new to Swing.
http://prntscr.com/bpz2ve
package gui;
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.*;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextArea;
public class GUI extends Frame {
public static void main(String[] args) {
JFrame frame = new JFrame("Hello World - YaBoiAce");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setSize(500, 300);
// Layout //
frame.setLayout(new BorderLayout());
// Swing Component //
final JTextArea textarea = new JTextArea();
JButton jbutton = new JButton("Click me");
// Add Component to content pane
Container c = frame.getContentPane();
c.add(textarea,BorderLayout.CENTER);
c.add(jbutton, BorderLayout.SOUTH);
// Action Listener
jbutton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
textarea.append("Hello");
} // Eclipse says 'missing ;' on this line.
}
private static void setDefaultCloseOperation(int exitOnClose) {
}
}
Eclipse says "Missing ;" But when I put that in, It highlights the ; saying "Missing ;" again. It keeps on doing that. Any help?
It is on the line marked with:
// Eclipse says 'missing ;' on this line.

There are many problems in your code:
As stated in the
comments
by #HovercraftFullOfEels:
You're not matching closing parenthesis on your addActionListener method too. Again good code formatting will help you see this.
// Action Listener
jbutton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
textarea.append("Hello");
} // Eclipse says 'missing ;' on this line.
}); //HERE YOU NEED TO ADD: );
You're extending Frame (Maybe you were trying to extend JFrame)
and creating a JFrame object, choose which one you want to use
(Recommended to create the object instead of extending, because if
you extend a JFrame your class is a JFrame and cannot be
included somewhere else and you're not changing it's functionallity
either so, no need to extend).
You're creating a private static method
private static void setDefaultCloseOperation(int exitOnClose) {}
That method should be public and belongs to JFrame class, I guess your IDE wrote that when you extended Frame instead of JFrame.
Frame belongs to java.awt while JFrame belongs to javax.swing so, they are not the same.
You're creating your windows and every component inside your main
method instead of the constructor
You're adding your components to a Container but never add that container to your JFrame, so you need to call
frame.setContentPane(c);
So your code should look like this:
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.*;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class GUI {
JFrame frame;
public GUI() {
frame = new JFrame("Hello World - YaBoiAce");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setSize(500, 300);
// Layout //
frame.setLayout(new BorderLayout());
// Swing Component //
final JTextArea textarea = new JTextArea();
JButton jbutton = new JButton("Click me");
frame.add(textarea,BorderLayout.CENTER);
frame.add(jbutton, BorderLayout.SOUTH);
// Add Component to content pane
Container c = frame.getContentPane();
c.add(textarea,BorderLayout.CENTER);
c.add(jbutton, BorderLayout.SOUTH);
frame.setContentPane(c);
// Action Listener
jbutton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
textarea.append("Hello");
} // Eclipse says 'missing ;' on this line.
});
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> new GUI());
}
}

Overlapping issue in Swing

I'm encountering this issue in Java Swing:
Both Magenta and Green components are JButtons. I'm using absolute layout for this. When hovering to Green, it overlaps Magenta even if no layout manager is applied nor JLayeredPane used.
Any reason for this behavior? How can I make sure the Magenta stays on top when hovering to Green?
Edit 2:
Just to be clear with my goal, the idea for this is to make a UI similar to Android Notification Bar with Assistive Touch. Assume that the Notification Bar is a layer and the Assistive Touch is the topmost layer. The problem with using a transparent layer in JLayeredPane is that if a layer/panel occupies the whole frame even when set to transparent, the layers underneath it are not drawn.

The answer is very simple: don't use absolute layout, use a real LayoutManager. In this case, it seems that BorderLayout will do the job just fine.
See this example:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.SwingUtilities;
public class TestLayout {
protected void initUI() {
JFrame frame = new JFrame("test");
Container cp = frame.getContentPane();
cp.setLayout(new BorderLayout());
cp.add(createColoredButton(Color.BLACK, Color.MAGENTA, "Hello World 1"), BorderLayout.NORTH);
cp.add(createColoredButton(Color.BLACK, Color.GREEN, "Hello World 2"), BorderLayout.EAST);
cp.add(createColoredButton(Color.WHITE, Color.BLUE, "Hello World 3"), BorderLayout.CENTER);
// frame.pack();
frame.setSize(600, 600);
frame.setVisible(true);
}
private JButton createColoredButton(Color fgColor, Color bgColor, final String text) {
final JButton button = new JButton(text);
button.setBorderPainted(false);
button.setFocusPainted(false);
button.setForeground(fgColor);
button.setBackground(bgColor);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(button, "You just clicked: " + text);
}
});
return button;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new TestLayout().initUI();
}
});
}
}

Java Swing: problems with width

I have problems with understanding the behavior of my application. I want to create a simple window (1000x700px), divided into two parts (250px and 750px width respectively). I tried the following code:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Example extends JFrame
{
private static final long serialVersionUID = 1L;
public Example()
{
this.setSize(1000, 700);
this.setTitle("Example");
this.setResizable(false);
this.setLayout(new FlowLayout(FlowLayout.LEFT, 0, 0));
JPanel navigation_panel_wrap = new JPanel();
JPanel content_panel_wrap = new JPanel();
navigation_panel_wrap.setPreferredSize(new Dimension(250, 700));
content_panel_wrap.setPreferredSize(new Dimension(750, 700));
content_panel_wrap.setBackground(Color.green);
navigation_panel_wrap.setBackground(Color.red);
this.getContentPane().add(navigation_panel_wrap);
this.getContentPane().add(content_panel_wrap);
}
public static void main(String[] args)
{
Example example = new Example();
example.setVisible(true);
}
}
As you can see I manually set layout manager for JFrame (FlowLayout instead of BorderLayout with zero horizontal and vertical gaps). Of course, I can just use BorderLayout and than use add() method with BorderLayout.EAST and BorderLayout.WEST parameters, but I want to understand what's wrong with FlowLayout.
When I run my application, I get the following (no green JPanel):
If I decrease width of, for example, content_panel_wrap and make it 744px instead of 750px, everything works correctly.
So the question is - what are these strange 6 pixels? I'm not sure this value is constant for all operating systems, so I want to understand its origin.

There's nothing wrong with FlowLayout but you will need to call pack() for all components to be sized.

As for your codes problem (+1 to #Reimeus) calling pack() is the solution.
as per docs:
Causes this Window to be sized to fit the preferred size and layouts
of its subcomponents. If the window and/or its owner are not yet
displayable, both are made displayable before calculating the
preferred size. The Window will be validated after the preferredSize
is calculated.
Tips:
Dont extend JFrame unnecessarily.
Use Event Dispatch Thread when creating and changing UI components:
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
// create UI components etc here
}
});
Dont call setPreferredSize() rather override getPrefferedSize() of component.
Dont call setSize(...) on JFrame rather call JFrame#pack() before setting it visible.
Dont forget to call JFrame#defaultCloseOperation(..) or your initial/EDT thread will not be terminated when JFrame is closed.
Here is an example combining my advice and your code:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Example {
private final JFrame frame;
public Example() {
frame = new JFrame();
frame.setTitle("Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//app exited when frame closes
frame.setResizable(false);
frame.setLayout(new FlowLayout(FlowLayout.LEFT, 0, 0));
JPanel navigation_panel_wrap = new JPanel() {
#Override
public Dimension getPreferredSize() {
return new Dimension(250, 700);
}
};
JPanel content_panel_wrap = new JPanel() {
#Override
public Dimension getPreferredSize() {
return new Dimension(750, 700);
}
};
content_panel_wrap.setBackground(Color.green);
navigation_panel_wrap.setBackground(Color.red);
frame.add(navigation_panel_wrap);
frame.add(content_panel_wrap);
//pack frame (size components to preferred size)
frame.pack();
frame.setVisible(true);//make frame visible
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Example();
}
});
}
}