Develop Reference

Java FlowLayout

I am writing some Java code that allows the user to see a frame with JLabel, JTextField and JButton.
I want the JLabel to be called "Count" and I have a problem with FlowLayout.
I want the interface to look like this:
Instead, I have this:
This is my code:
package modul1_Interfate_Grafice;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class Exercitiu04 implements ActionListener {
private JFrame frame;
private JLabel labelCount;
private JTextField tfCount;
private JButton buttonCount;
private int count = 0;
public void go() {
frame = new JFrame("Java Counter");
labelCount = new JLabel("Counter");
labelCount.setLayout(new FlowLayout());
frame.getContentPane().add(BorderLayout.CENTER, labelCount);
tfCount = new JTextField(count + " ", 10);
tfCount.setEditable(false);
labelCount.add(tfCount);
buttonCount = new JButton("Count");
labelCount.add(buttonCount);
buttonCount.addActionListener(this);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(350, 150);
frame.setLocation(400, 200);
}
#Override
public void actionPerformed(ActionEvent event) {
count++;
tfCount.setText(count + "");
}
public static void main(String[] args) {
Exercitiu04 a = new Exercitiu04();
a.go();
}
}

Solve it.
Instead of labelCount.setLayout(new FlowLayout());` i should have had
frame.setLayout(new FlowLayout());

From description of JLabel class,
JLabel is:
A display area for a short text string or an image, or both.
But here: labelCount.add(tfCount) and here labelCount.add(buttonCount) you're trying to put a textfield and a button into a label. In this case, positions of button and textfield are controlled by FlowLayout but position of the text in the label is not.
Instead of this, you should put all of your elements in common JPanel, like this:
...
frame = new JFrame("Java Counter");
frame.setLayout(new BorderLayout());
JPanel wrapper = new JPanel(); // JPanel has FlowLayout by default
labelCount = new JLabel("Counter");
labelCount.setLayout(new FlowLayout());
wrapper.add(labelCount);
tfCount = new JTextField(count + " ", 10);
tfCount.setEditable(false);
wrapper.add(tfCount);
buttonCount = new JButton("Count");
buttonCount.addActionListener(this);
wrapper.add(buttonCount);
frame.add(BorderLayout.CENTER, wrapper);
...
And, like MasterBlaster said, you should put swing methods in EDT.

There are only two things you should know about FlowLayout:
a) It is a default layout manager of the JPanel component
b) It is good for nothing.
This trivial layout cannot be achieved with FlowLayout.
When doing layouts in Swing, you should familiarize yourself
with some powerful layout managers. I recommend MigLayout and
GroupLayout.
package com.zetcode;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import net.miginfocom.swing.MigLayout;
/*
Simple UI with a MigLayout manager.
Author Jan Bodnar
Website zetcode.com
*/
public class MigLayoutCounterEx extends JFrame {
public MigLayoutCounterEx() {
initUI();
}
private void initUI() {
JLabel lbl = new JLabel("Counter");
JTextField field = new JTextField(10);
JButton btn = new JButton("Count");
createLayout(lbl, field, btn);
setTitle("Java Counter");
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private void createLayout(JComponent... arg) {
setLayout(new MigLayout());
add(arg[0]);
add(arg[1]);
add(arg[2]);
pack();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
MigLayoutCounterEx ex = new MigLayoutCounterEx();
ex.setVisible(true);
});
}
}
The example is trivial. You just put the three components into the
cells.
Screenshot:

You shouldn't use setSize when dealing with FlowLayout. Instead use pack(). It makes the window just about big enough to fit all your components in. That should tidy things up for you

Java - updating values in JFrame/JLabels

I am a beginner Java-coder and a few days ago I felt confident enough in my skills to start my first "big" project. It was basically a calculator, a GUI(only JFrame, JPanels, JLabels and Buttons) that would display data, accept user input, grab some more data from other classes, then calculate stuff and finally update the GUI with the new JLabel values. However I never managed to get the update part done properly, whenever I would press the 'process'-button it would create a new JFrame with the new values, while the old one was still up.
I tried the obvious stuff (repaint(), revalidate(), etc) but that didn't work at all, then I started to shift things around, put parts of the code into new classes, copied code from the net until it eventually worked. However the code was a total mess and I didn't even really understand what went exactly wrong in the first place, so I trashed the entire thing.
Here is a very simplified version of my code before things went downhill:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Test_1 extends JFrame {
public static class clicks{
static int clicks = 0;
public int getclicks(){
return clicks;
}
public void setclicks(){
clicks = clicks+1;
}
}
public Test_1(){
clicks getNumber = new clicks();
int x = getNumber.getclicks();
//FRAME AND LAYOUT
JFrame window = new JFrame();
window.getContentPane().setBackground(Color.darkGray);
window.getContentPane().setLayout(new BorderLayout(20,10));
window.setTitle("Test Frame 1");
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setResizable(true);
// Top JPanel
JPanel northpanel = new JPanel();
LayoutManager northlayout = new FlowLayout();
northpanel.setLayout(northlayout);
// Top JPanel content
JLabel nlabel1 = new JLabel("Hello North");
nlabel1.setPreferredSize(new Dimension(100,20));
northpanel.add(nlabel1);
JPanel westpanel = new JPanel();
LayoutManager westlayout = new BoxLayout(westpanel, BoxLayout.Y_AXIS);
westpanel.setLayout(westlayout);
JLabel wlabel1 = new JLabel("Hello West");
wlabel1.setPreferredSize(new Dimension(100,20));
westpanel.add(wlabel1);
JPanel eastpanel = new JPanel();
LayoutManager eastlayout = new BoxLayout(eastpanel, BoxLayout.Y_AXIS);
eastpanel.setLayout(eastlayout);
JLabel elabel1 = new JLabel ("Hello East");
elabel1.setPreferredSize(new Dimension(100,20));
eastpanel.add(elabel1);
JButton southbutton = new JButton("start");
southbutton.setPreferredSize(new Dimension(400,50));
southbutton.addActionListener(new Action());
JPanel centralpanel = new JPanel();
JLabel clabel1 = new JLabel("Clicks: " + x);
centralpanel.add(clabel1);
window.add(centralpanel, BorderLayout.CENTER);
window.add(southbutton, BorderLayout.SOUTH);
window.add(eastpanel, BorderLayout.EAST);
window.add(westpanel, BorderLayout.WEST);
window.add(northpanel, BorderLayout.NORTH);
window.pack();
window.setVisible(true);
}
public static void main(String[] args) {
Test_1 window_start = new Test_1();
}
static class Action implements ActionListener{
#Override
public void actionPerformed (ActionEvent e){
clicks Numbers = new clicks();
Numbers.setclicks();
int test = Numbers.getclicks();
System.out.println("Button works, Number of clicks: "+test);
Test_1 updateData = new Test_1();
}
}
}
I know that the ActionListener creates a new instance of my JFrame, however that was the closest I ever came to "updating the JFrame" before I turned the code into Spaghetti. I assume that the way I build my code is the cause of my problem but creating the Frame and its content it different classes didn't work at all.
So my questions are:
Is there something really obvious I missing? Would it be possible to make this run the way I want to without completely changing it?
Is there a more efficient way to create a GUI? I get the feeling that the way I made this is total garbage.
I read other questions that dealt with similar problems but maybe it's because I am still pretty bad at Java but I couldn't really tell if they were related to my problem. Also I really want to understand this, so copying someone elses code wouldn't help at all.
Any help or comments are appreciated.
btw, the class click is something I just put there as a placeholder.

Alrighty I managed to get it to work. It's probably against the Etiquette to answer to his own question but I thought it might be useful for some beginners(like me yesterday). So here is my new code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Test_1 extends JFrame {
public static class clicks{
static int clicks = 0;
public int getclicks(){
return clicks;
}
public void setclicks(){
clicks = clicks+1;
}
}
clicks getNumber = new clicks();
int x = getNumber.getclicks();
JPanel northpanel, westpanel, eastpanel, southpanel, centralpanel;
static JLabel nlabel1, nlabel2, nlabel3, nlabel4, nlabel5;
static JLabel wlabel1, wlabel2, wlabel3, wlabel4, wlabel5;
static JLabel elabel1, elabel2, elabel3, elabel4, elabel5;
static JLabel clabel1;
JButton southbutton;
String TextnL, TextwL, TexteL;
public Test_1(){
setBackground(Color.darkGray);
setLayout(new BorderLayout(20,10));
setTitle("Test Frame 1");
setSize(300,200);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setResizable(true);
setLocationRelativeTo(null);
setVisible(true);
nlabel1 = new JLabel("North_1");
nlabel2 = new JLabel("North_2");
nlabel3 = new JLabel("North_3");
nlabel4 = new JLabel("North_4");
nlabel5 = new JLabel("North_5");
wlabel1 = new JLabel("West_1 ");
wlabel2 = new JLabel("West_2 ");
wlabel3 = new JLabel("West_3 ");
wlabel4 = new JLabel("West_4 ");
wlabel5 = new JLabel("West_5 ");
elabel1 = new JLabel("East_1");
elabel2 = new JLabel("East_2");
elabel3 = new JLabel("East_3");
elabel4 = new JLabel("East_4");
elabel5 = new JLabel("East_5");
clabel1 = new JLabel("START");
southbutton = new JButton("Process");
southbutton.addActionListener(new Action());
northpanel = new JPanel();
northpanel.add(nlabel1);
northpanel.add(nlabel2);
northpanel.add(nlabel3);
northpanel.add(nlabel4);
northpanel.add(nlabel5);
add(northpanel, BorderLayout.NORTH);
westpanel = new JPanel();
LayoutManager wBox = new BoxLayout(westpanel, BoxLayout.Y_AXIS);
westpanel.setLayout(wBox);
westpanel.add(wlabel1);
westpanel.add(wlabel2);
westpanel.add(wlabel3);
westpanel.add(wlabel4);
westpanel.add(wlabel5);
add(westpanel, BorderLayout.WEST);
eastpanel = new JPanel();
LayoutManager eBox = new BoxLayout(eastpanel, BoxLayout.Y_AXIS);
eastpanel.setLayout(eBox);
eastpanel.add(elabel1);
eastpanel.add(elabel2);
eastpanel.add(elabel3);
eastpanel.add(elabel4);
eastpanel.add(elabel5);
add(eastpanel, BorderLayout.EAST);
centralpanel = new JPanel();
centralpanel.add(clabel1);
add(centralpanel, BorderLayout.CENTER);
add(southbutton, BorderLayout.SOUTH);
}
public static void main(String[] args) {
Test_1 window_start = new Test_1();
}
static class Action implements ActionListener{
#Override
public void actionPerformed (ActionEvent e){
clicks Numbers = new clicks();
Numbers.setclicks();
int test = Numbers.getclicks();
clabel1.setText("clicks: "+test);
}
}
}
And again, any comments/suggestions are welcome.

Can't get my Jscrollpane working in my Jtextarea

I've looked around quite a lot on google and followed several examples however I can't seem to get my JScrollPane working on a textarea in a JPanel.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import javax.swing.event.*;
class main
{
public static void main(String Args[])
{
frame f1 = new frame();
}
}
class frame extends JFrame
{
JButton B = new JButton("B");
JButton button = new JButton("A");
JTextArea E = new JTextArea("some lines", 10, 20);
JScrollPane scrollBar = new JScrollPane(E);
JPanel grid = new JPanel ();
frame()
{
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(500,800);
setTitle("Mobile Phone App");
setLocationRelativeTo(null);
E.setLineWrap(true);
E.setEditable(false);
grid.add(button);
button.addActionListener(new action());
grid.add(B);
B.addActionListener(new action());
//grid.add(E);
grid.getContentPane().add(scrollBar);
add(grid);
setVisible(true);
}
class action implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String V = E.getText();
if(e.getSource() == button)
{
E.setText(V + "A is pressed");
}
if(e.getSource() == B)
{
E.setText(V + "B is pressed");
}
}
}
}
Would be great if someone can see where I am going wrong. I added JscrollPane in which I added the text area "e" in it.

E.setColumns(10);
E.setRows(5);
E.setPreferredSize(new Dimension(10,5)); // delete this
Don't hardcode a preferred size. The preferred size is overriding your attempt to set the rows/columns. So get rid of that line.
Note, you can also specify the row/columns when you create the text area:
JTextArea textArea = new JTextArea(5, 10);
to provide a hint to the intial size of the text area. Now the text area can change in size as text is added or removed and the scrollbar will appear when needed.
Also follow standard java naming conventions. Variable names should NOT start with an upper case character.

Right I got it!
Basically I had to add it in differently...the way I was approaching it was wrong!
grid.add(scrollBar, BorderLayout.CENTER);

Replacing a JPanel with a different JPanel

Hi this is a bit of a basic question. In my code I create a gui in a constructor then nest a ActionListener class to handle button changes. This code will create the gui and the action listener runs through the actionPerformed method correctly. However, I've tried multiple ways to change the panel in the gui but I feel like the way I have the program set up it is not possible for this to work. Sorry if this is a repeat but after searching for a while on S.O. I haven't found a good example that would help me with my problem.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import org.math.plot.Plot2DPanel;
import org.math.plot.plotObjects.BaseLabel;
public class GraphGui extends JFrame {
//default width and height of the GUI
private static final int WIDTH = 1200;
private static final int HEIGHT = 700;
GraphPlot gp = new GraphPlot();
Plot2DPanel plotPanel =gp.determinePlotToPlot("duration");
/**
* This is the constructor that initializes the JFrame and the layout of the GUI.
* The radio buttons are also created here and grouped accordingly.
*/
public GraphGui() {
//title of GUI
setTitle("VibeTech Graph Gui");
//First JRadioButton for date vs duration
JRadioButton durToDate = new JRadioButton("Duration vs. Date");
durToDate.addActionListener(new RadioButtonListener());
durToDate.setActionCommand("duration");
durToDate.setSelected(true);
//JRadioButton for weight vs date
JRadioButton weightToDate = new JRadioButton("Weight vs. Date");
weightToDate.addActionListener(new RadioButtonListener());
weightToDate.setActionCommand("weight");
//JRadioButton for plan type vs date
JRadioButton planToDate = new JRadioButton("Plan vs. Date");
planToDate.addActionListener(new RadioButtonListener());
planToDate.setActionCommand("level");
//button group of the buttons to display them as one group
ButtonGroup group = new ButtonGroup();
group.add(planToDate);
group.add(weightToDate);
group.add(durToDate);
//create JPanel to add objects to
JPanel jplRadio = new JPanel();
jplRadio.setLayout(new GridLayout(0, 1));
//add radio buttons
jplRadio.add(planToDate);
jplRadio.add(weightToDate);
jplRadio.add(durToDate);
Plot2DPanel dvt = new Plot2DPanel();
dvt.addLinePlot("Duration over Time", gp.getDate(), gp.getDuration());
BaseLabel title = new BaseLabel("Duration over Time", Color.RED,
0.5, 1.1);
title.setFont(new Font("Courier", Font.BOLD, 20));
dvt.addPlotable(title);
dvt.setAxisLabels("Time", "Duration");
setLayout(new BorderLayout());
add(jplRadio, BorderLayout.WEST);
add(plotPanel, BorderLayout.EAST);
setSize(WIDTH, HEIGHT);
setVisible(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
//main method to run program
public static void main(String [ ] args)
{
//create new GUI
#SuppressWarnings("unused")
GraphGui test = new GraphGui();
}
//create a radio button listener to switch graphs on button press
class RadioButtonListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
if(e.getActionCommand().equals("duration")) {
plotPanel = gp.determinePlotToPlot("duration");
} else if (e.getActionCommand().equals("weight")) {
plotPanel = gp.determinePlotToPlot("weight");
} else if (e.getActionCommand().equals("level")) {
plotPanel = gp.determinePlotToPlot("level");
}
//here is where I tried to do removes, adds, and validates but
//I have trouble getting to the frame itself to remove the JPanel
//component. I think this is a setup problem.
}
}
}

You would need to add the panel and revalidate/repaint the JFrame for it to appear:
add(plotPanel, BorderLayout.EAST);
revalidate();
repaint();
Better to use CardLayout to manage this type of functionality.

Try using CardLayout for switching between panels. Here is my solution for a similar question: https://stackoverflow.com/a/9377623/544983

Make JTextPane's Text Move Sideways Instead of a New Line

I am working with the JTextPane and am trying to make the text move sideways instead of a newline like the JTextField. I have tried searching and looking through the JTextPane's API but I haven't found anything useful. Could someone show me some type of method or process (that can be used in a main class) that could help me? Thanks you!
P.S.
I am aware of using the JScrollPane, but I would like to avoid that since I would like the JTextPane to look like a JTextField as much as possible.

JTextPane textPane = new JTextPane();
JPanel noWrapPanel = new JPanel( new BorderLayout() );
noWrapPanel.add( textPane );
JScrollPane scrollPane = new JScrollPane( noWrapPanel );
Solution Source
Plus:
JScrollPane.setVerticalScrollBarPolicy(VERTICAL_SCROLLBAR_NEVER);
JScrollPane.setHorizontalScrollBarPolicy(HORIZONTAL_SCROLLBAR_NEVER);
EDIT:
Solution without JScrollPane
import java.awt.Component;
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextPane;
import javax.swing.plaf.ComponentUI;
import javax.swing.text.StyledDocument;
public class NonWrappingTextPane extends JTextPane {
public NonWrappingTextPane() {
super();
}
public NonWrappingTextPane(StyledDocument doc) {
super(doc);
}
// Override getScrollableTracksViewportWidth
// to preserve the full width of the text
#Override
public boolean getScrollableTracksViewportWidth() {
Component parent = getParent();
ComponentUI ui = this.getUI();
return parent != null ? (ui.getPreferredSize(this).width <= parent.getSize().width) : true;
}
// Test method
public static void main(String[] args) {
String content = "The plaque on the Apollo 11 Lunar Module\n"
+ "\"Eagle\" reads:\n\n"
+ "\"Here men from the planet Earth first\n"
+ "set foot upon the Moon, July, 1969 AD\n"
+ "We came in peace for all mankind.\"\n\n"
+ "It is signed by the astronauts and the\n"
+ "President of the United States.";
JFrame f = new JFrame("Non-wrapping Text Pane Example");
JPanel p = new JPanel();
NonWrappingTextPane nwtp = new NonWrappingTextPane();
nwtp.setText(content);
p.add(nwtp);
f.getContentPane().setLayout(new GridLayout(2, 1));
f.getContentPane().add(p);
f.setSize(300, 200);
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}