Develop Reference

I've trying to add a JPanel to my JFrame on click,but i dont find my error

I am trying to get some Java skills back because i worked for a long time in webdevelopment. Now I am just create a main Jframe where are a little Menu and a Class createSchueler extends JPanel.
So what I want to do if you go into the Menu click Neu > Schueler
A new Jpanel should be created and added to the Window
Main Class
public class MainWindow {
private JFrame frame;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
MainWindow window = new MainWindow();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public MainWindow() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 807, 541);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
JPanel createSchueler = new createSchueler();
JMenuBar menuBar = new JMenuBar();
frame.setJMenuBar(menuBar);
JMenu mnNewMenu = new JMenu("Neu");
mnNewMenu.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
createSchueler.setVisible(true);
frame.getContentPane().add(createSchueler);
}
});
menuBar.add(mnNewMenu);
JMenuItem mntmSchler = new JMenuItem("Sch\u00FCler");
mnNewMenu.add(mntmSchler);
JMenu mnBearbeiten = new JMenu("Bearbeiten");
menuBar.add(mnBearbeiten);
JMenuItem mntmSchler_1 = new JMenuItem("Sch\u00FCler");
mnBearbeiten.add(mntmSchler_1);
}
}
The createSchueler Class extends JPanel that i want to add to the frame
public class createSchueler extends JPanel {
private JTextField textField;
private JTextField textField_1;
private JTextField textField_2;
/**
* Create the panel.
*/
public createSchueler() {
setLayout(null);
JLabel lblNeuenSchuelerErstellen = new JLabel("Neuen Schueler erstellen");
lblNeuenSchuelerErstellen.setFont(new Font("Tahoma", Font.PLAIN, 22));
lblNeuenSchuelerErstellen.setBounds(29, 27, 268, 27);
add(lblNeuenSchuelerErstellen);
JLabel lblVorname = new JLabel("Vorname");
lblVorname.setBounds(29, 102, 46, 14);
add(lblVorname);
textField = new JTextField();
textField.setBounds(97, 99, 172, 20);
add(textField);
textField.setColumns(10);
JLabel lblNachname = new JLabel("Nachname");
lblNachname.setBounds(29, 133, 69, 14);
add(lblNachname);
textField_1 = new JTextField();
textField_1.setBounds(97, 130, 172, 20);
add(textField_1);
textField_1.setColumns(10);
JLabel lblGeburtstag = new JLabel("Geburtstag");
lblGeburtstag.setBounds(29, 169, 69, 14);
add(lblGeburtstag);
textField_2 = new JTextField();
textField_2.setBounds(97, 166, 172, 20);
add(textField_2);
textField_2.setColumns(10);
ButtonGroup bg = new ButtonGroup();
JRadioButton rdbtnMnnlich = new JRadioButton("M\u00E4nnlich");
rdbtnMnnlich.setBounds(29, 206, 69, 23);
bg.add(rdbtnMnnlich);
JRadioButton rdbtnWeiblich = new JRadioButton("Weiblich");
rdbtnWeiblich.setBounds(97, 206, 109, 23);
bg.add(rdbtnWeiblich);
}
}
Everything is important hopefully :D

Use a CardLayout to swap JPanels rather than adding them by hand. If you must add them by hand, be sure that the receiving container's layout manager is up to the task and handles the addition well. For example BorderLayout would take it fine, but GroupLayout won't. If you do add or remove by hand, call revalidate(); and repaint() on the container after these changes.
Also you're using null layout in your added JPanel and contentPane which will completely ruin it's preferredSize calculation. Never use this layout. Learn to use and then use the layout managers. This is your main mistake.
For more on this, please read: Why is it frowned upon to use a null layout in Swing?
For example:
import java.awt.CardLayout;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class MainGui {
public static final String SCHUELER_PANEL = "Schueler Panel";
public static final String EMPTY = "Empty Panel";
private JPanel mainPanel = new JPanel();
private JMenuBar menuBar = new JMenuBar();
private CardLayout cardLayout = new CardLayout();
private SchuelerPanel schuelerPanel = new SchuelerPanel();
public MainGui() {
mainPanel.setLayout(cardLayout);
mainPanel.add(new JLabel(), EMPTY); // empty label
mainPanel.add(schuelerPanel, SCHUELER_PANEL);
JMenu menu = new JMenu("Panel");
menu.add(new JMenuItem(new SwapPanelAction(EMPTY)));
menu.add(new JMenuItem(new SwapPanelAction(SCHUELER_PANEL)));
menuBar.add(menu);
}
public JPanel getMainPanel() {
return mainPanel;
}
public JMenuBar getMenuBar() {
return menuBar;
}
#SuppressWarnings("serial")
private class SwapPanelAction extends AbstractAction {
public SwapPanelAction(String title) {
super(title);
int mnemonic = (int) title.charAt(0);
putValue(MNEMONIC_KEY, mnemonic);
}
#Override
public void actionPerformed(ActionEvent e) {
cardLayout.show(mainPanel, (String) getValue(NAME));
}
}
private static void createAndShowGui() {
MainGui mainGui = new MainGui();
JFrame frame = new JFrame("Main Gui");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainGui.getMainPanel());
frame.setJMenuBar(mainGui.getMenuBar());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
and
import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.util.HashMap;
import java.util.Map;
import javax.swing.*;
#SuppressWarnings("serial")
public class SchuelerPanel extends JPanel {
private static final String TITLE_TEXT = "Lorem Ipsum Dolor Sit Amet";
public static final String[] LABEL_STRINGS = {"Monday", "Tuesday", "Wednesday"};
private Map<String, JTextField> labelFieldMap = new HashMap<>();
public SchuelerPanel() {
JLabel titleLabel = new JLabel(TITLE_TEXT, JLabel.CENTER);
titleLabel.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 20));
JPanel labelFieldPanel = new JPanel(new GridBagLayout());
for (int i = 0; i < LABEL_STRINGS.length; i++) {
addToPanel(labelFieldPanel, LABEL_STRINGS[i], i);
}
// Don't do what I'm doing here: avoid "magic" numbers!
setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
setLayout(new BorderLayout(10, 10));
add(titleLabel, BorderLayout.PAGE_START);
add(labelFieldPanel, BorderLayout.CENTER);
}
// get the text from the JTextField based on the JLabel associated with it
public String getText(String labelText) {
JTextField textField = labelFieldMap.get(labelText);
if (textField == null) {
throw new IllegalArgumentException("For labelText: " + labelText);
}
return textField.getText();
}
private void addToPanel(JPanel gblUsingPanel, String labelString, int row) {
JLabel label = new JLabel(labelString);
label.setFont(label.getFont().deriveFont(Font.BOLD));
JTextField textField = new JTextField(10);
labelFieldMap.put(labelString, textField);
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = row;
gbc.anchor = GridBagConstraints.WEST;
gbc.fill = GridBagConstraints.BOTH;
gbc.weightx = 0.0;
gbc.weighty = 0.0;
gbc.insets = new Insets(5, 5, 5, 5);
gblUsingPanel.add(label, gbc);
gbc.gridx = 1;
gbc.anchor = GridBagConstraints.EAST;
gbc.fill = GridBagConstraints.HORIZONTAL;
gblUsingPanel.add(textField, gbc);
}
private static void createAndShowGui() {
JFrame frame = new JFrame("SchuelerPanel");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new SchuelerPanel());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}

Java JFrame Graphics dont show up

public class FrameTest extends JFrame {
private JPanel contentPane;
private JPanel spielPane;
private JPanel infoPane;
private JButton btnStart;
private JLabel lblRunde;
private Monster monster1;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
FrameTest frame = new FrameTest();
frame.setVisible(true);
Monster m = new Monster();
frame.repaintSpielPanel();
}
catch (Exception e) {
e.printStackTrace();
}
}
});
}
public FrameTest() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 800, 600);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
contentPane.setLayout(null);
setContentPane(contentPane);
spielPane = new JPanel();
spielPane.setBounds(6, 6, 566, 566);
spielPane.setLayout(null);
spielPane.setBackground(Color.yellow);
contentPane.add(spielPane);
infoPane = new JPanel();
infoPane.setBounds(578, 6, 216, 566);
infoPane.setLayout(null);
infoPane.setBackground(Color.yellow);
contentPane.add(infoPane);
btnStart = new JButton("Start");
btnStart.setBounds(44, 6, 117, 29);
infoPane.add(btnStart);
lblRunde = new JLabel("Runde");
lblRunde.setBounds(77, 47, 61, 16);
infoPane.add(lblRunde);
monster1 = new Monster();
monster1.setVisible(true);
spielPane.add(monster1);
}
private class Monser extends JLabel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.RED);
g.fillRect(0, 0, 10, 10);
}
}
public void repaintSpielPanel() {
spielPane.repaint();
}
}
I tried to put a Rectangle into my frame, but it isn't there. I'm just starting to program, so probably I just don't know how to get it onto the screen. Pls help!

Don't paint in a JLabel which isn't opaque. Instead do so in a JPanel.
Don't use null layouts and setBounds(...). While null layouts and setBounds() might seem to Swing newbies like the easiest and best way to create complex GUI's, the more Swing GUI'S you create the more serious difficulties you will run into when using them. They won't resize your components when the GUI resizes, they are a royal witch to enhance or maintain, they fail completely when placed in scrollpanes, they look gawd-awful when viewed on all platforms or screen resolutions that are different from the original one.
Most important, you never add an instance of your drawing component, here Monser, to anything. To see that this is true, search your code for any calls to new Monser(). If a constructor isn't being called, an instance isn't going to be created.
Also note that you're creating a Monster instance, and this is a class that you've not shown us.
You're adding it to a null layout using JPanel, and so since it has no size, it won't show at all. Again, don't use null layouts.
For example:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridLayout;
import javax.swing.*;
#SuppressWarnings("serial")
public class MyTest extends JPanel {
private static final Color BG = Color.yellow;
private static final int GAP = 8;
private JButton btnStart = new JButton("Start");
private JLabel lblRunde = new JLabel("Runde", SwingConstants.CENTER);
private MonsterPanel monsterPanel = new MonsterPanel(600, 600, BG);
public MyTest() {
JPanel buttonPanel = createButtonPanel();
buttonPanel.setBackground(BG);
setLayout(new BorderLayout(GAP, GAP));
setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
add(monsterPanel, BorderLayout.CENTER);
add(buttonPanel, BorderLayout.LINE_END);
}
private JPanel createButtonPanel() {
JPanel btnPanel = new JPanel();
btnPanel.setBackground(BG);
JPanel gridPanel = new JPanel(new GridLayout(0, 1, 0, 5));
gridPanel.setOpaque(false);
gridPanel.add(btnStart);
gridPanel.add(lblRunde);
btnPanel.add(gridPanel);
return btnPanel;
}
private static void createAndShowGui() {
MyTest mainPanel = new MyTest();
JFrame frame = new JFrame("MyFrameTest");
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(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class MonsterPanel extends JPanel {
public static final int MONST_WIDTH = 10;
public static final Color MONST_COLOR = Color.red;
private int prefW;
private int prefH;
private int monstX = 0;
private int monstY = 0;
public MonsterPanel(int prefW, int prefH, Color bkgrnd) {
this.prefW = prefW;
this.prefH = prefH;
setBackground(bkgrnd);
}
public void setMonstXY(int x, int y) {
this.monstX = x;
this.monstY = y;
repaint();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(MONST_COLOR);
g.fillRect(monstX, monstY, MONST_WIDTH, MONST_WIDTH);
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(prefW, prefH);
}
}

Calling method from one class in other

I know that this kind of issue has been discussed here many times, but I'm confused. I'm totally beginner in Java and I honestly don't know what to do and I admit that I don't have that much time to read whole documentation provided by Oracle. Here's my problem:
I'm trying to program a GUI for my program that will be show interference of acoustic waves. Mathematical functionality doesn't matter in here. I've got two classes called Window and Sliders. Window is intended to be a 'main GUI class' and Sliders is supposed to inherit (?) from it.
This comes from another issue that I need to implement ActionListener in class Window and ChangeListener in Sliders class. I heard that one class can't implement several classes that's why I made two.
Now, I wrote a little bit chaotic those two classes, but I don't know how to combine them. It's really silly, but after C++ I'm pretty confused how to tell the program that it is supposed to show in one frame either buttons defined in Window class and sliders defined in Sliders class. Currently it shows only buttons I want to make it showing sliders too.
I'm very sorry for chaotic pseudo code, please help. Please, try to explain as simply as you can/possible. Please feel free to ignore overrided methods, they're not finished yet.
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.*;
public class Window extends JFrame implements ActionListener
{
private JButton showChord, playSound, getSample, getPlot;
private JLabel chordInfo;
private JPanel basicFunctions;
public Window()
{
init();
}
private void init()
{
setVisible(true);
setSize(new Dimension(1000,500));
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
basicFunctions = new JPanel();
FlowLayout basicLayout = new FlowLayout();
basicFunctions.setLayout(basicLayout);
showChord = new JButton("Akord");
playSound = new JButton("Odtwórz");
getSample = new JButton("Pobierz dźwięk");
getPlot = new JButton("Pobierz wykres");
showChord.addActionListener(this);
playSound.addActionListener(this);
getSample.addActionListener(this);
getPlot.addActionListener(this);
basicFunctions.add(showChord);
basicFunctions.add(playSound);
basicFunctions.add(getSample);
basicFunctions.add(getPlot);
add(basicFunctions);
Sliders param = new Sliders();
}
public static void main(String[] args)
{
Window frame = new Window();
}
//Action Listener
#Override
public void actionPerformed(ActionEvent a)
{
Object event = a.getSource();
if(event == showChord)
{
}
else if(event == playSound)
{
}
else if(event == getSample)
{
}
else if(event == getPlot)
{
}
}
}
import java.awt.*;
import javax.swing.event.ChangeEvent;
import javax.swing.*;
import javax.swing.event.ChangeListener;
public class Sliders extends Window implements ChangeListener
{
private JPanel sliders, sliderSub;
private JTextField accAmplitude, accFrequency, accPhase;
private JSlider amplitude, frequency, phase;
private double amplitudeValue, frequencyValue, phaseValue;
public Sliders()
{
sliders = new JPanel();
sliders.setLayout(new FlowLayout());
amplitude = new JSlider(0,100,0);
amplitude.setMajorTickSpacing(10);
amplitude.setMinorTickSpacing(5);
amplitude.setPaintTicks(true);
amplitude.setPaintLabels(true);
frequency = new JSlider(0,10,0);
frequency.setMajorTickSpacing(1);
frequency.setMinorTickSpacing(1/10);
frequency.setPaintTicks(true);
frequency.setPaintLabels(true);
phase = new JSlider(0,1,0);
phase.setMinorTickSpacing(2/10);
phase.setPaintTicks(true);
phase.setPaintLabels(true);
accAmplitude = new JTextField();
accFrequency = new JTextField();
accPhase = new JTextField();
sliders.add(amplitude, BorderLayout.NORTH);
sliders.add(frequency, BorderLayout.CENTER);
sliders.add(phase, BorderLayout.SOUTH);
add(sliders);
}
#Override
public void stateChanged(ChangeEvent arg0)
{
}
}
I've done this so far, but those text fields just stopped showing sliders values and I don't know why. They are defined in the Parameters class and Window class. Can someone help? Additionally in the future I'd like to make those text fields editable so that you can set slider value by typing it in the text field.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.BevelBorder;
import javax.swing.event.*;
public class Window extends JPanel
{
private JMenuBar mainMenu = new JMenuBar();
private Plot plot = new Plot();
private Parameters param = new Parameters();
private JComboBox chooseChord = new JComboBox();
private JButton playSound = new JButton("Odtwórz");
private JButton getSample = new JButton("Pobierz dźwięk");
private JButton getPlot = new JButton("Pobierz wykres");
private JPanel mainPanel = new JPanel();
private JPanel subPanel = new JPanel();
private JPanel buttonsPanel = new JPanel();
private JPanel slidersPanel = new JPanel();
private JLabel chord = new JLabel("Akord:");
private JTextField aValue = new JTextField();
private JTextField fValue = new JTextField();
private JTextField pValue = new JTextField();
public Window()
{
mainPanel.setLayout(new FlowLayout());
buttonsPanel.setLayout(new BoxLayout(buttonsPanel, BoxLayout.Y_AXIS));
slidersPanel.setLayout(new BorderLayout());
subPanel.setLayout(new BorderLayout());
chooseChord.addItem("A");
chooseChord.addItem("A#");
chooseChord.addItem("Ab");
chooseChord.addItem("B");
chooseChord.addItem("Bb");
chooseChord.addItem("C");
chooseChord.addItem("C#");
chooseChord.addItem("Cb");
chooseChord.addItem("D");
chooseChord.addItem("D#");
chooseChord.addItem("E");
chooseChord.addItem("F");
chooseChord.addItem("F#");
buttonsPanel.add(chord);
buttonsPanel.add(chooseChord);
buttonsPanel.add(Box.createRigidArea(new Dimension(0,10)));
buttonsPanel.add(playSound);
buttonsPanel.add(Box.createRigidArea(new Dimension(0,10)));
buttonsPanel.add(getSample);
buttonsPanel.add(Box.createRigidArea(new Dimension(0,10)));
buttonsPanel.add(getPlot);
buttonsPanel.setBorder(BorderFactory.createTitledBorder("Menu"));
slidersPanel.add(param);
JMenu langMenu = new JMenu("Język");
mainMenu.add(langMenu);
subPanel.add(buttonsPanel, BorderLayout.NORTH);
subPanel.add(slidersPanel, BorderLayout.SOUTH);
mainPanel.add(subPanel);
mainPanel.add(plot);
add(mainPanel);
param.addAmplitudeListener(new ChangeListener()
{
public void stateChanged(ChangeEvent a)
{
double ampValue = param.getAmplitudeValue();
aValue.setText(String.valueOf(ampValue));
}
}
);
param.addFrequencyListener(new ChangeListener()
{
public void stateChanged(ChangeEvent f)
{
double frValue = param.getFrequencyValue();
fValue.setText(String.valueOf(frValue));
}
}
);
param.addPhaseListener(new ChangeListener()
{
public void stateChanged(ChangeEvent p)
{
double phValue = param.getPhaseValue();
pValue.setText(String.valueOf(phValue));
}
}
);
}
public JMenuBar getmainMenu()
{
return mainMenu;
}
private static void GUI()
{
Window mainPanel = new Window();
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.setJMenuBar(mainPanel.getmainMenu());
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
GUI();
}
}
);
}
}
class Parameters extends JPanel
{
private JPanel pane = new JPanel();
private JPanel ampPanel = new JPanel();
private JPanel frPanel = new JPanel();
private JPanel phPanel = new JPanel();
private JSlider amplitude = new JSlider(0,100,0);
private JSlider frequency = new JSlider(0,10000,0);
private JSlider phase = new JSlider(0,180,0);
private JLabel pLabel = new JLabel("Faza");
private JLabel aLabel = new JLabel("Amplituda (dB)");
private JLabel fLabel = new JLabel("Częstotliwość (Hz)");
private JTextField preciseAmplitude = new JTextField(3);
private JTextField preciseFrequency = new JTextField(4);
private JTextField precisePhase = new JTextField(3);
public Parameters()
{
preciseAmplitude.setEditable(true);
preciseFrequency.setEditable(true);
precisePhase.setEditable(true);
pane.setLayout(new BoxLayout(pane, BoxLayout.PAGE_AXIS));
ampPanel.setLayout(new FlowLayout());
frPanel.setLayout(new FlowLayout());
phPanel.setLayout(new FlowLayout());
amplitude.setMajorTickSpacing(10);
amplitude.setMinorTickSpacing(5);
amplitude.setPaintTicks(true);
amplitude.setPaintLabels(true);
frequency.setMajorTickSpacing(2000);
frequency.setMinorTickSpacing(100);
frequency.setPaintTicks(true);
frequency.setPaintLabels(true);
phase.setMajorTickSpacing(2/10);
phase.setPaintTicks(true);
phase.setPaintLabels(true);
setBorder(BorderFactory.createTitledBorder("Parametry fali"));
ampPanel.add(aLabel);
ampPanel.add(preciseAmplitude);
pane.add(ampPanel);
pane.add(Box.createRigidArea(new Dimension(0,5)));
pane.add(amplitude);
pane.add(Box.createRigidArea(new Dimension(0,10)));
frPanel.add(fLabel);
frPanel.add(preciseFrequency);
pane.add(frPanel);
pane.add(Box.createRigidArea(new Dimension(0,5)));
pane.add(frequency);
pane.add(Box.createRigidArea(new Dimension(0,10)));
phPanel.add(pLabel);
phPanel.add(precisePhase);
pane.add(phPanel);
pane.add(Box.createRigidArea(new Dimension(0,5)));
pane.add(phase);
pane.add(Box.createRigidArea(new Dimension(0,10)));
add(pane);
}
public int getAmplitudeValue()
{
return amplitude.getValue();
}
public int getFrequencyValue()
{
return frequency.getValue();
}
public int getPhaseValue()
{
return phase.getValue();
}
public void addAmplitudeListener(ChangeListener ampListener)
{
amplitude.addChangeListener(ampListener);
}
public void addFrequencyListener(ChangeListener frListener)
{
frequency.addChangeListener(frListener);
}
public void addPhaseListener(ChangeListener phListener)
{
phase.addChangeListener(phListener);
}
}
class Plot extends JPanel
{
private JPanel componentWave = new JPanel();
private JPanel netWave = new JPanel();
private JLabel componentLabel = new JLabel("Fale składowe");
private JLabel netLabel = new JLabel("Fala wypadkowa");
private JLabel wave = new JLabel("Wybierz falę składową");
private JPanel labels = new JPanel();
private JComboBox chooseWave = new JComboBox();
public Plot()
{
labels.setLayout(new BoxLayout(labels, BoxLayout.PAGE_AXIS));
componentWave.setBackground(new Color(255,255,255));
netWave.setBackground(new Color(255,255,255));
componentWave.setBorder(BorderFactory.createBevelBorder(BevelBorder.LOWERED));
netWave.setBorder(BorderFactory.createBevelBorder(BevelBorder.LOWERED));
componentWave.setPreferredSize(new Dimension(400,200));
netWave.setPreferredSize(new Dimension(400,200));
labels.add(wave);
labels.add(Box.createRigidArea(new Dimension(0,10)));
labels.add(chooseWave);
labels.add(componentLabel);
labels.add(componentWave);
labels.add(Box.createRigidArea(new Dimension(0,20)));
labels.add(netLabel);
labels.add(netWave);
add(labels);
}
}

Window is intended to be a 'main GUI class' and Sliders is supposed to inherit (?) from it.
Nope: this is a misuse of inheritance and will only lead to problems since the Windows instance that Sliders inherently is, is completely distinct from the displayed Windows instance. What you need to do is to pass references.
For example, the following code uses outside classes for the JButton and JMenuItem Actions (Actions are like ActionListeners on steroids), and uses a class that holds a JSlider that allows itside classes to attach listeners to the slider.
import java.awt.Component;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Foo extends JPanel {
private static final long serialVersionUID = 1L;
private Action helloAction = new HelloAction("Hello", KeyEvent.VK_H);
private Action exitAction = new ExitAction("Exit", KeyEvent.VK_X);
private JMenuBar menuBar = new JMenuBar();
private JTextField sliderValueField = new JTextField(10);
private Bar bar = new Bar();
public Foo() {
sliderValueField.setEditable(false);
sliderValueField.setFocusable(false);
add(new JButton(helloAction));
add(new JButton(exitAction));
add(new JLabel("Slider Value: "));
add(sliderValueField);
add(bar);
JMenu fileMenu = new JMenu("File");
fileMenu.setMnemonic(KeyEvent.VK_F);
fileMenu.add(new JMenuItem(exitAction));
fileMenu.add(new JMenuItem(helloAction));
menuBar.add(fileMenu);
bar.addSliderListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
int sliderValue = bar.getSliderValue();
sliderValueField.setText(String.valueOf(sliderValue));
}
});
}
public JMenuBar getJMenuBar() {
return menuBar;
}
private static void createAndShowGui() {
Foo mainPanel = new Foo();
JFrame frame = new JFrame("Foo");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.setJMenuBar(mainPanel.getJMenuBar());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class HelloAction extends AbstractAction {
public HelloAction(String name, int mnemonic) {
super(name); // sets name property and gives button its title
putValue(MNEMONIC_KEY, mnemonic);
}
#Override
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(null, "Hello!");
}
}
class ExitAction extends AbstractAction {
private static final long serialVersionUID = 1L;
public ExitAction(String name, int mnemonic) {
super(name);
putValue(MNEMONIC_KEY, mnemonic);
}
#Override
public void actionPerformed(ActionEvent e) {
Component component = (Component) e.getSource();
Window win = SwingUtilities.getWindowAncestor(component);
if (win == null) {
// if no window, then a JMenuItem held in a JPopupMenu
JPopupMenu popup = (JPopupMenu) component.getParent();
component = popup.getInvoker();
win = SwingUtilities.getWindowAncestor(component);
}
win.dispose();
}
}
class Bar extends JPanel {
private JSlider slider = new JSlider(0, 100, 50);
public Bar() {
slider.setPaintLabels(true);
slider.setPaintTicks(true);
slider.setMajorTickSpacing(20);
slider.setMinorTickSpacing(5);
slider.setSnapToTicks(true);
setBorder(BorderFactory.createTitledBorder("Slider Panel"));
add(slider);
}
public int getSliderValue() {
return slider.getValue();
}
// one way to let outside classes listen for changes
public void addSliderListener(ChangeListener listener) {
slider.addChangeListener(listener);
}
}
You ask about decimal labels, and yes this can be done but requires use of a label table. For example,
JSlider slider = new JSlider(0, 100, 50);
slider.setPaintLabels(true);
slider.setPaintTicks(true);
slider.setMajorTickSpacing(20);
slider.setMinorTickSpacing(2);
Dictionary<Integer, JLabel> labels = new Hashtable<>();
for (int i = 0; i <= 100; i += 20) {
labels.put(i, new JLabel(String.format("%.1f", i / 200.0)));
}
slider.setLabelTable(labels);
Which displays as:
You would also have to translate the value back from int to its corresponding floating point number.

I can use getActionCommand to change the label content, but I can't use it to change the color?

So with the help of others here I finally managed to code a button that alternates the label "Hello World!" to "Hello Universe!" and back again. I used the code below, and used the same way to try and change the color, but it didn't work as expected. I've been searching for hours on this, but with no avail. Thank you for reading, anything helps!
Code:
package game;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Javagame extends JPanel implements ActionListener{
protected JButton changetext;
protected JButton red;
protected JButton green;
private JLabel label;
public Javagame() {
add(changetext = new JButton("Button!"));
changetext.setPreferredSize(new Dimension(50, 50));
changetext.setActionCommand("change");
add(red = new JButton("Red"));
red.setPreferredSize(new Dimension(50, 50));
red.setActionCommand("changecolorRed");
add(green = new JButton("Green"));
green.setPreferredSize(new Dimension(50, 50));
green.setActionCommand("changecolorGreen");
changetext.addActionListener(this);
label = new JLabel("Hello World!", SwingConstants.CENTER);
label.setFont(new Font("Arial", Font.BOLD, 20));
label.setForeground(new Color(0x009900));
setLayout(new BorderLayout());
add(label, BorderLayout.CENTER);
add(changetext, BorderLayout.NORTH);
add(red, BorderLayout.WEST);
add(green, BorderLayout.EAST);
}
public void actionPerformed(ActionEvent e) {
if ("change".equals(e.getActionCommand())) {
label.setText("Hello Universe!");
changetext.setActionCommand("changeBack");
}
if ("changeBack".equals(e.getActionCommand())) {
label.setText("Hello World!");
changetext.setActionCommand("change");
}
if ("changecolorRed".equals(e.getActionCommand())) {
label.setForeground(new Color(0xFF0000));
}
if ("changecolorGreen".equals(e.getActionCommand())) {
label.setForeground(new Color(0x009900));
}
}
private static void createWindow(){
JFrame frame = new JFrame("Javagame");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setPreferredSize(new Dimension(500,500));
JPanel panel = new JPanel(new BorderLayout());
Javagame newContentPane = new Javagame();
newContentPane.setOpaque(true);
frame.setContentPane(newContentPane);
frame.setLocationRelativeTo(null);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
createWindow();
}
}

You need to add ActionListeners to buttons for them to work.
This is usually done via a simple method call: red.addActionListener(someListener);
Also:
get rid of your setPreferredsize(...) method calls, and instead let components set their own size. At the most you can override getPreferredSize() if need be, but try to limit that.
Avoid having your GUI code implement your listener interfaces as that leads to confusing and difficult to manage code. Better to use anonymous inner listeners or private inner classes or stand alone listener classes.
For example:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class JavaGame2 extends JPanel {
private static final int PREF_W = 600;
private static final int PREF_H = 400;
private static final Font LABEL_FONT = new Font("Arial", Font.BOLD, 20);
private static final Color[] FOREGROUNDS = { new Color(0x009900),
new Color(0x990000), new Color(0x000099), new Color(0x999900),
new Color(0x990099), new Color(0x009999) };
private static final String[] LABEL_TEXTS = { "Hello World!",
"Goodbye World!", "Hola Todo el Mundo!", "Hasta la Vista Baby!",
"Whatever!!" };
private JButton changetextButton;
private JButton changeColorButton;
private JLabel label;
private int labelTextIndex = 0;
private int foregroundIndex = 0;
public JavaGame2() {
label = new JLabel(LABEL_TEXTS[labelTextIndex], SwingConstants.CENTER);
label.setFont(LABEL_FONT);
label.setForeground(FOREGROUNDS[foregroundIndex]);
// example of anonymous inner ActionListener:
changetextButton = new JButton("Change Text");
changetextButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent evt) {
labelTextIndex++;
labelTextIndex %= LABEL_TEXTS.length;
label.setText(LABEL_TEXTS[labelTextIndex]);
}
});
// example of use of an anonymous AbstractAction:
changeColorButton = new JButton(new AbstractAction("Change Color") {
#Override
public void actionPerformed(ActionEvent e) {
foregroundIndex++;
foregroundIndex %= FOREGROUNDS.length;
label.setForeground(FOREGROUNDS[foregroundIndex]);
}
});
setLayout(new BorderLayout());
add(changetextButton, BorderLayout.NORTH);
add(changeColorButton, BorderLayout.SOUTH);
add(label, BorderLayout.CENTER);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
private static void createAndShowGui() {
JavaGame2 mainPanel = new JavaGame2();
JFrame frame = new JFrame("Java Game 2");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}

JProgressbar width using Grid/FlowLayout

I'm working on a downloader which looks like this at the moment:
The JFrame uses a BorderLayout.
In the NORTH, I have a JPanel(FlowLayout). In the SOUTH there is also a JPanel(FlowLayout), in the WEST I just have a JTextArea (in a JScrollPane). This is all shown correctly. However, in the EAST I currently have a JPanel(GridLayout(10, 1)).
I want to show up to 10 JProgressBars in the EAST section which are added and removed from the panel dynamically. The problem is, I can not get them to look like I want to them to look: I want the JProgressBars' width to fill up the entire EAST section because 1) This gives the app a more symmetrical look and 2) The ProgressBars may contain long strings that don't fit at the moment. I've tried putting the JPanel that contains the GridLayout(10, 1) in a flowlayout and then put that flowlayout in the EAST section, but that didn't work either.
My code (SSCCE) is currently as follows:
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.HashMap;
import java.util.Map;
public class Main {
public static void main(String[] args) {
new DownloadFrame();
}
private static class DownloadFrame extends JFrame {
private JButton downloadButton;
private JTextField threadIdTextField;
private JTextArea downloadStatusTextArea;
private JScrollPane scrollPane;
private JTextField downloadLocationTextField;
private JButton downloadLocationButton;
private JPanel North;
private JPanel South;
private JPanel ProgressBarPanel;
private Map<String, JProgressBar> progressBarMap;
public DownloadFrame() {
InitComponents();
InitLayout();
AddComponents();
AddActionListeners();
setVisible(true);
setSize(700, 300);
}
private void InitComponents() {
downloadButton = new JButton("Dowload");
threadIdTextField = new JTextField(6);
downloadStatusTextArea = new JTextArea(10, 30);
scrollPane = new JScrollPane(downloadStatusTextArea, ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
downloadLocationTextField = new JTextField(40);
downloadLocationButton = new JButton("...");
North = new JPanel();
South = new JPanel();
ProgressBarPanel = new JPanel();
progressBarMap = new HashMap<String, JProgressBar>();
}
private void InitLayout() {
North.setLayout(new FlowLayout());
South.setLayout(new FlowLayout());
ProgressBarPanel.setLayout(new GridLayout(10, 1));
}
private void AddComponents() {
North.add(threadIdTextField);
North.add(downloadButton);
add(North, BorderLayout.NORTH);
add(ProgressBarPanel, BorderLayout.EAST);
South.add(downloadLocationTextField);
South.add(downloadLocationButton);
add(South, BorderLayout.SOUTH);
add(scrollPane, BorderLayout.WEST);
}
private void AddActionListeners() {
downloadButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
addNewProgessBar(threadIdTextField.getText());
}
});
}
public void addNewProgessBar(String threadId) {
JProgressBar progressBar = new JProgressBar();
progressBar.setStringPainted(true);
progressBarMap.put(threadId, progressBar);
drawProgessBars();
}
void drawProgessBars() {
ProgressBarPanel.removeAll();
for (JProgressBar progressBar : progressBarMap.values()) {
ProgressBarPanel.add(progressBar);
}
validate();
repaint();
}
}
}
Thanks in advance.
EDIT
Easiest solution: change
add(ProgressBarPanel, BorderLayout.EAST);
to
add(ProgressBarPanel, BorderLayout.CENTER);

import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.HashMap;
import java.util.Map;
public class Main {
public static void main(String[] args) {
new DownloadFrame();
}
private static class DownloadFrame extends JFrame {
private JButton downloadButton;
private JTextField threadIdTextField;
private JTextArea downloadStatusTextArea;
private JScrollPane scrollPane;
private JTextField downloadLocationTextField;
private JButton downloadLocationButton;
private JPanel North;
private JPanel South;
private JPanel ProgressBarPanel;
private Map<String, JProgressBar> progressBarMap;
public DownloadFrame() {
InitComponents();
AddComponents();
AddActionListeners();
pack();
setVisible(true);
//setSize(700, 300);
}
private void InitComponents() {
setLayout(new BorderLayout());
downloadButton = new JButton("Dowload");
threadIdTextField = new JTextField(6);
downloadStatusTextArea = new JTextArea(10, 30);
scrollPane = new JScrollPane(downloadStatusTextArea, ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
downloadLocationTextField = new JTextField(40);
downloadLocationButton = new JButton("...");
North = new JPanel(new FlowLayout());
South = new JPanel(new FlowLayout());
ProgressBarPanel = new JPanel(new GridLayout(0, 1));
ProgressBarPanel.setBorder(new LineBorder(Color.black));
ProgressBarPanel.setPreferredSize(new Dimension(300,20));
progressBarMap = new HashMap<String, JProgressBar>();
}
private void AddComponents() {
North.add(threadIdTextField);
North.add(downloadButton);
add(North, BorderLayout.NORTH);
add(ProgressBarPanel, BorderLayout.EAST);
South.add(downloadLocationTextField);
South.add(downloadLocationButton);
add(South, BorderLayout.SOUTH);
add(scrollPane, BorderLayout.WEST);
}
private void AddActionListeners() {
downloadButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
addNewProgessBar(threadIdTextField.getText());
}
});
}
public void addNewProgessBar(String threadId) {
JProgressBar progressBar = new JProgressBar();
progressBar.setStringPainted(true);
progressBarMap.put(threadId, progressBar);
drawProgessBars();
}
void drawProgessBars() {
ProgressBarPanel.removeAll();
for (JProgressBar progressBar : progressBarMap.values()) {
ProgressBarPanel.add(progressBar);
}
validate();
repaint();
}
}
}

well. that possible, but in your example CENTER area occupated some Rectangle, its hard to reduce/remove CENTER area to the zero Size
to the North JPanel (BorderLayout) place another JPanel and put it to the EAST (with LayoutManager would be GridLayout(1,2,10,10)) and put here two JComponents JTextField - threadIdTextField and JButton - downloadButton, there you are needed setPreferredSize 1) for JComponents (correct way) or 2) for whole JPanel (possible way too)
JScrollPane with JTextArea must be placed to the CENTER area
JPanel with JProgressBars place to EAST, but again set same PreferredSize as for JPanel with JTextField and JButton from the NORTH
SOUTH JPanel remains without changes

Please post a compilable runnable small program for the quickest best help, an SSCCE.
Suggestions include using GridLayout(0, 1) (variable number of rows, one column), or display the JProgressBars in a JList that uses a custom renderer that extends JProgressBar.
Edit 1:
I know that Andrew has already posted the accepted answer (and 1+ for an excellent answer), but I just wanted to demonstrate that this can be done readily with a JList, something like so:
import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import java.util.Random;
import javax.swing.*;
public class EastProgressList extends JPanel {
private DefaultListModel myListModel = new DefaultListModel();
private JList myList = new JList(myListModel);
private JTextField downloadUrlField = new JTextField(10);
public EastProgressList() {
JButton downLoadBtn = new JButton("Download");
downLoadBtn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
downloadAction();
}
});
JPanel northPanel = new JPanel();
northPanel.add(new JLabel("File to Download:"));
northPanel.add(downloadUrlField);
northPanel.add(Box.createHorizontalStrut(15));
northPanel.add(downLoadBtn);
myList.setCellRenderer(new ProgressBarCellRenderer());
JScrollPane eastSPane = new JScrollPane(myList);
eastSPane.setPreferredSize(new Dimension(200, 100));
setLayout(new BorderLayout());
add(new JScrollPane(new JTextArea(20, 30)), BorderLayout.CENTER);
add(northPanel, BorderLayout.NORTH);
add(eastSPane, BorderLayout.EAST);
}
private void downloadAction() {
String downloadUrl = downloadUrlField.getText();
final MyData myData = new MyData(downloadUrl);
myListModel.addElement(myData);
myData.addPropertyChangeListener(new PropertyChangeListener() {
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getPropertyName().equals(MyData.VALUE)) {
myList.repaint();
if (myData.getValue() >= 100) {
myListModel.removeElement(myData);
}
}
}
});
}
private class ProgressBarCellRenderer extends JProgressBar implements ListCellRenderer {
protected ProgressBarCellRenderer() {
setBorder(BorderFactory.createLineBorder(Color.blue));
}
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {
//setText(value.toString());
MyData myData = (MyData)value;
setValue(myData.getValue());
setString(myData.getText());
setStringPainted(true);
return this;
}
}
private static void createAndShowUI() {
JFrame frame = new JFrame("EastProgressList");
frame.getContentPane().add(new EastProgressList());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
createAndShowUI();
}
});
}
}
class MyData {
public static final int TIMER_DELAY = 300;
public static final String VALUE = "value";
protected static final int MAX_DELTA_VALUE = 5;
private String text;
private int value = 0;
private Random random = new Random();
private PropertyChangeSupport pcSupport = new PropertyChangeSupport(this);
public MyData(String text) {
this.text = text;
new Timer(TIMER_DELAY, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
int deltaValue = random.nextInt(MAX_DELTA_VALUE);
int newValue = value + deltaValue;
if (newValue >= 100) {
newValue = 100;
((Timer)e.getSource()).stop();
}
setValue(newValue);
}
}).start();
}
public String getText() {
return text;
}
public int getValue() {
return value;
}
public void setValue(int value) {
int oldValue = this.value;
this.value = value;
PropertyChangeEvent pcEvent = new PropertyChangeEvent(this, VALUE, oldValue, value);
pcSupport.firePropertyChange(pcEvent);
}
public void addPropertyChangeListener(PropertyChangeListener pcListener) {
pcSupport.addPropertyChangeListener(pcListener);
}
}
This results in a GUI looking like so: