Thread: JButton...

i cant make the button appear on my panel...
why?

package xTestx;   import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JSlider; import javax.swing.JButton; import javax.swing.SwingConstants; import javax.swing.event.ChangeEvent; import javax.swing.event.ChangeListener;   import java.awt.Color; import java.awt.Label; import java.awt.Point; import java.awt.Dimension; import java.awt.Font; import java.awt.HeadlessException;   /** * Simple JSlider. * * @author */   public class PropertiesWindow implements ChangeListener {   JFrame propertiesWindow;   JPanel windowPanel;   JButton button;   JSlider widthSlider; JSlider heightSlider; JSlider pointXSlider; JSlider pointYSlider;   JSlider redSchemeSlider; JSlider blueSchemeSlider; JSlider greenSchemeSlider;   JLabel widthLabel; JLabel heightLabel; JLabel pointYLabel; JLabel pointXLabel;   JLabel redSchemeLabel; JLabel blueSchemeLabel; JLabel greenSchemeLabel;   // the spot where the sliders color combination will be displayed Label colorSpot;   // the color spot label name Label spotLabel;   // center point for the shape Point centerPoint;   // dimension of the shape Dimension shapeDimension;   // minimum value for the width of the shape private static final int WIDTH_MIN_VALUE = 100;   // maximum value for width of the shape private static final int WIDTH_MAX_VALUE = 500;   // minimum value for the height of the shape private static final int HEIGHT_MIN_VALUE = 100;   // maximum value for the height of the shape private static final int HEIGHT_MAX_VALUE = 500;   // minimum value for the center point (point x) of the shape private static final int MIN_POINT_X = 200;   // maximum value for the center point (point x) of the shape private static final int MAX_POINT_X = 800;   // minimum value for the center point (point y) of the shape private static final int MIN_POINT_Y = 100;   // maximum value for the center point (point y) of the shape private static final int MAX_POINT_Y = 500;   // constant value for color scheme slider's minor tick private static final int COLOR_SLIDER_MINOR_TICK = 5;   // constant value for color scheme slider's major tick private static final int COLOR_SLIDER_MAJOR_TICK = 10;   // constant value of minor tick for the geometric pattern sliders private static final int MINOR_TICK = 10;   // constant value of major tick for the geometric pattern sliders private static final int MAJOR_TICK = 100;   public void showPropertyWindow() throws HeadlessException {   propertiesWindow = new JFrame("Properties Window");   windowPanel = new JPanel();   button = new JButton("My Button");   widthSlider = new JSlider(WIDTH_MIN_VALUE, WIDTH_MAX_VALUE); heightSlider = new JSlider(HEIGHT_MIN_VALUE, HEIGHT_MAX_VALUE); pointXSlider = new JSlider(MIN_POINT_X, MAX_POINT_X); pointYSlider = new JSlider(MIN_POINT_Y, MAX_POINT_Y);   // sliders for the adjustment of the color redSchemeSlider = new JSlider(SwingConstants.VERTICAL, 0 , 255, 0); blueSchemeSlider = new JSlider(SwingConstants.VERTICAL, 0, 255, 0); greenSchemeSlider = new JSlider(SwingConstants.VERTICAL, 0 ,255, 0);   widthLabel = new JLabel(); heightLabel = new JLabel(); pointXLabel = new JLabel(); pointYLabel = new JLabel();   // Label for each color redSchemeLabel = new JLabel(); blueSchemeLabel = new JLabel(); greenSchemeLabel = new JLabel();   // spot where the color that will be generated by the color sliders is displayed colorSpot = new Label();   // Label for the width value slider widthLabel.setText("Width : "); widthLabel.setBounds(20, 10, 50, 40);   // set the slider properties for the width widthSlider.setBounds(20, 35, 250, 50); widthSlider.setMinorTickSpacing(MINOR_TICK); widthSlider.setMajorTickSpacing(MAJOR_TICK); widthSlider.setPaintTicks(true); widthSlider.setPaintLabels(true); widthSlider.setToolTipText("Width"); widthSlider.setForeground(Color.GRAY); widthSlider.addChangeListener(this);   // Label for the height value slider heightLabel.setText("Height : "); heightLabel.setBounds(20, 90, 60, 70);   // set the slider properties for the height heightSlider.setBounds(20, 135, 250, 45); heightSlider.setMinorTickSpacing(MINOR_TICK); heightSlider.setMajorTickSpacing(MAJOR_TICK); heightSlider.setPaintTicks(true); heightSlider.setPaintLabels(true); heightSlider.setToolTipText("Height"); heightSlider.setForeground(Color.GRAY);   // Label for the point x (center point) pointXLabel.setText("Point x : "); pointXLabel.setBounds(20, 175, 70, 100);   // set the properties of the point x(center point) slider pointXSlider.setBounds(20, 230, 250, 50); pointXSlider.setMinorTickSpacing(MINOR_TICK); pointXSlider.setMajorTickSpacing(MAJOR_TICK); pointXSlider.setPaintTicks(true); pointXSlider.setPaintLabels(true); pointXSlider.setToolTipText("Center Point (x)"); pointXSlider.setForeground(Color.GRAY);   // Label for the point y (center point) pointYLabel.setText("Point y : "); pointYLabel.setBounds(20, 240, 70, 155);   // set the properties of the point y(center point) slider pointYSlider.setBounds(20, 330, 250, 45); pointYSlider.setMinorTickSpacing(MINOR_TICK); pointYSlider.setMajorTickSpacing(MAJOR_TICK); pointYSlider.setPaintTicks(true); pointYSlider.setPaintLabels(true); pointYSlider.setToolTipText("Center Point (y)"); pointYSlider.setForeground(Color.GRAY);   // Label for each of the color scheme slider redSchemeLabel.setText("Red : "); redSchemeLabel.setBounds(300, 5, 50 , 50); greenSchemeLabel.setText("Green : "); greenSchemeLabel.setBounds(530, 5, 50, 50); blueSchemeLabel.setText("Blue : "); blueSchemeLabel.setBounds(420, 5, 50, 50);   // set the properties of the red color scheme slider redSchemeSlider.setBounds(310, 40, 50, 280); redSchemeSlider.setMinorTickSpacing(COLOR_SLIDER_MINOR_TICK); redSchemeSlider.setMajorTickSpacing(COLOR_SLIDER_MAJOR_TICK); redSchemeSlider.setPaintTicks(true); redSchemeSlider.setPaintLabels(false); redSchemeSlider.setToolTipText("Red"); redSchemeSlider.setForeground(Color.RED); redSchemeSlider.addChangeListener(this);   // set the properties of the green color scheme slider greenSchemeSlider.setBounds(550, 40, 50, 280); greenSchemeSlider.setMinorTickSpacing(COLOR_SLIDER_MINOR_TICK); greenSchemeSlider.setMajorTickSpacing(COLOR_SLIDER_MAJOR_TICK); greenSchemeSlider.setPaintTicks(true); greenSchemeSlider.setPaintLabels(false); greenSchemeSlider.setToolTipText("Green"); greenSchemeSlider.setForeground(Color.GREEN); greenSchemeSlider.addChangeListener(this);   // set the properties of the blue color shceme slider blueSchemeSlider.setBounds(430, 40, 50, 280); blueSchemeSlider.setMinorTickSpacing(COLOR_SLIDER_MINOR_TICK); blueSchemeSlider.setMajorTickSpacing(COLOR_SLIDER_MAJOR_TICK); blueSchemeSlider.setPaintTicks(true); blueSchemeSlider.setPaintLabels(false); blueSchemeSlider.setToolTipText("Blue"); blueSchemeSlider.setForeground(Color.blue); blueSchemeSlider.addChangeListener(this);   // set the color spot in the panel colorSpot.setText("Shape's Color."); colorSpot.setFont(new Font("Monospaced",Font.CENTER_BASELINE ,20)); colorSpot.setBounds(320, 350, 260, 40); colorSpot.setAlignment(Label.CENTER); colorSpot.setForeground(new Color(255, 255, 255)); colorSpot.setBackground(new Color(0, 0, 0));   // show the labels windowPanel.add(widthLabel); windowPanel.add(heightLabel); windowPanel.add(pointXLabel); windowPanel.add(pointYLabel); windowPanel.add(redSchemeLabel); windowPanel.add(blueSchemeLabel); windowPanel.add(greenSchemeLabel);   // show the sliders windowPanel.add(widthSlider); windowPanel.add(heightSlider); windowPanel.add(pointXSlider); windowPanel.add(pointYSlider); windowPanel.add(redSchemeSlider); windowPanel.add(blueSchemeSlider); windowPanel.add(greenSchemeSlider); windowPanel.add(colorSpot);   windowPanel.add(button);   windowPanel.setLayout(null); windowPanel.setDoubleBuffered(false);   propertiesWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); propertiesWindow.setSize(700, 450); propertiesWindow.setLocation(350, 200); propertiesWindow.setVisible(true); propertiesWindow.getContentPane().add(windowPanel); }   public static void main(String[] args) {   PropertiesWindow enhc = new PropertiesWindow();   enhc.showPropertyWindow(); }   public void stateChanged(ChangeEvent event) {   int width = widthSlider.getValue(); int height = heightSlider.getValue(); int pointX = pointXSlider.getValue(); int pointY = pointYSlider.getValue(); int red = redSchemeSlider.getValue(); int green = greenSchemeSlider.getValue(); int blue = blueSchemeSlider.getValue();   if ((red >= 200) && (red <= 255)) {   if ((green >= 200) && (green <= 255)) {   if ((blue >= 200) && (green <= 255)) {   colorSpot.setForeground(Color.BLACK); } } } else if ((red <= 50) && (red >= 0)) {   if ((green <= 50) && (green >= 0)) {   if ((blue <= 50) && (blue >= 0)) {   colorSpot.setForeground(Color.WHITE); } } }   // set the spot color according to the colors generated by sliders colorSpot.setBackground(new Color(red, green, blue)); } }

but with this code, the button appears perfectly.

package xxxGARBAGExxx;   import javax.swing.*; import java.awt.*;   /** * * @author */   public class NewClass extends JFrame {   JFrame frame; JButton button; JPanel panel;   public void sample() {   frame = new JFrame("Sample"); panel = new JPanel(); button = new JButton("My Button!");   panel.add(button); frame.setDefaultCloseOperation(EXIT_ON_CLOSE); // is this a new class of the JFrame class? frame.setSize(500, 500); frame.setVisible(true); frame.getContentPane().add(panel);   }   public static void main(String[] args) {   NewClass object = new NewClass();   object.sample(); } }

The layout of your windowPanel is set to null, so your button is probably not being placed correctly until you set its bounds. I would encourage you to use layout managers (Using Layout Managers (The Java™ Tutorials > Creating a GUI With JFC/Swing > Laying Out Components Within a Container)), letting swing align and position things for you and having components position (or reposition) properly when windows are resized.