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Java Simple Simulator

I'm trying to make a sort of simple soccer simulator. This is the code I created after watching tutorials and i know its pretty bad. All i want to do is add a value to the team, like 1 for the best team and 10 for the worst, and when i click simulate a pop up would show up telling me which team would win given the teams value. But i cant figure out how to do it.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.TitledBorder;
public class sim extends JPanel {
public sim() {
// JFrame constructor
super(true);
JRadioButton chelsea, arsenal, chelsea2, arsenal2;
this.setLayout(new GridLayout(3,0));
ButtonGroup group = new ButtonGroup();
ButtonGroup group2 = new ButtonGroup();
// takes image and saves it the the variable
Icon a = new ImageIcon(getClass().getResource("a.PNG"));
Icon c = new ImageIcon(getClass().getResource("c.JPG"));
chelsea = new JRadioButton("Chelsea",c);
chelsea.setHorizontalTextPosition(AbstractButton.CENTER);
chelsea.setVerticalTextPosition(AbstractButton.BOTTOM);
arsenal = new JRadioButton("Arsenal",a);
arsenal.setHorizontalTextPosition(AbstractButton.CENTER);
arsenal.setVerticalTextPosition(AbstractButton.BOTTOM);
group.add(chelsea);
group.add(arsenal);
JLabel label = new JLabel("");
TitledBorder titled = new TitledBorder("Team 1");
label.setBorder(titled);
chelsea.setBorder(titled);
arsenal.setBorder(titled);
JButton button = new JButton("Simulate");
button.setHorizontalAlignment(JButton.CENTER);
add(button, BorderLayout.CENTER);
chelsea2 = new JRadioButton("Chelsea",c);
chelsea2.setHorizontalTextPosition(AbstractButton.CENTER);
chelsea2.setVerticalTextPosition(AbstractButton.BOTTOM);
arsenal2 = new JRadioButton("Arsenal",a);
arsenal2.setHorizontalTextPosition(AbstractButton.CENTER);
arsenal2.setVerticalTextPosition(AbstractButton.BOTTOM);
group2.add(chelsea2);
group2.add(arsenal2);
JLabel label2 = new JLabel("");
TitledBorder titled2 = new TitledBorder("Team 2");
label2.setBorder(titled2);
chelsea2.setBorder(titled);
arsenal2.setBorder(titled);
add(label);
add(chelsea);
add(arsenal);
add(button);
add(chelsea2);
add(arsenal2);
HandlerClass handler = new HandlerClass();
chelsea.addActionListener(handler);
}
private class HandlerClass implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
//JOptionPane.showMessageDialog(null, String.format("%s", e.getActionCommand()));
}
}
public static void main(String[] args) {
JFrame frame = new JFrame("Final");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(1920, 1080);
frame.setContentPane(new sim());
frame.setVisible(true);
}
}

Firstly capitalize the name of your class always in Java, then check this code :
public class Sim extends JPanel {
public Sim() {
// JFrame constructor
super(true);
JRadioButton chelsea, arsenal, chelsea2, arsenal2;
this.setLayout(new GridLayout(3,0));
ButtonGroup group = new ButtonGroup();
ButtonGroup group2 = new ButtonGroup();
// takes image and saves it the the variable
Icon a = new ImageIcon("/home/mehdi/Pictures/ICONS/Test/1.png");
Icon c = new ImageIcon("/home/mehdi/Pictures/ICONS/Test/2.png");
chelsea = new JRadioButton("Chelsea",c);
chelsea.setHorizontalTextPosition(AbstractButton.CENTER);
chelsea.setVerticalTextPosition(AbstractButton.BOTTOM);
arsenal = new JRadioButton("Arsenal",a);
arsenal.setHorizontalTextPosition(AbstractButton.CENTER);
arsenal.setVerticalTextPosition(AbstractButton.BOTTOM);
group.add(chelsea);
group.add(arsenal);
final JLabel label = new JLabel("");
TitledBorder titled = new TitledBorder("Team 1");
label.setBorder(titled);
chelsea.setBorder(titled);
arsenal.setBorder(titled);
JButton button = new JButton("Simulate");
button.setHorizontalAlignment(JButton.CENTER);
add(button, BorderLayout.CENTER);
chelsea2 = new JRadioButton("Chelsea",c);
chelsea2.setHorizontalTextPosition(AbstractButton.CENTER);
chelsea2.setVerticalTextPosition(AbstractButton.BOTTOM);
arsenal2 = new JRadioButton("Arsenal",a);
arsenal2.setHorizontalTextPosition(AbstractButton.CENTER);
arsenal2.setVerticalTextPosition(AbstractButton.BOTTOM);
group2.add(chelsea2);
group2.add(arsenal2);
JLabel label2 = new JLabel("");
TitledBorder titled2 = new TitledBorder("Team 2");
label2.setBorder(titled2);
chelsea2.setBorder(titled);
arsenal2.setBorder(titled);
add(label);
add(chelsea);
add(arsenal);
add(button);
add(chelsea2);
add(arsenal2);
button.addActionListener(new HandlerClass(label));
}
private class HandlerClass implements ActionListener{
final JLabel label;
public HandlerClass(JLabel label){
this.label = label;
}
public void actionPerformed(ActionEvent e)
{
label.setText("SSSSSSSSSSSSSsssss");
JOptionPane.showMessageDialog(null, "Something");
}
}
public static void main(String[] args) {
JFrame frame = new JFrame("Final");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(1920, 1080);
frame.setContentPane(new Sim());
frame.setVisible(true);
}
}

Swing Number Format Exception

For some reason the AddListener class below doesn't work, and I keep getting a number format exception. Could anyone please tell me the reason for this. It seems to me as if it should work.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class BabyCalculator extends JFrame {
JFrame theFrame = this;
JTextField addField; // Declaring this here so that you can access the variable from other places. MAKE SURE TO NOT DECLARE THIS AGAIN IN THE CONSTRUCTOR
JTextField totalField;
public BabyCalculator() {
//You set this up so that you can refer to the frame using the inner class below.
setDefaultCloseOperation(EXIT_ON_CLOSE);
setName("Baby Calculator");
setLayout(new GridLayout(3, 0));
//add
JLabel addLabel = new JLabel("Amount to add:");
addField = new JTextField(10);
JButton addButton = new JButton("add");
addButton.addActionListener(new AddListener());
//multiply
JLabel multiplyLabel = new JLabel("Amount to multiply:");
JTextField multiplyField = new JTextField(10);
JButton multiplyButton = new JButton("multiply");
//total
JLabel totalLabel = new JLabel("Total");
totalField = new JTextField(10);
totalField.setEditable(false);
JButton stopButton = new JButton("Stop");
stopButton.addActionListener(new StopListener());
//Create Panels
JPanel topRow = new JPanel(new BorderLayout());
JPanel middleRow = new JPanel(new BorderLayout());
JPanel bottomRow = new JPanel(new FlowLayout());
//Add the top Row
topRow.add(addLabel, BorderLayout.WEST);
topRow.add(addField, BorderLayout.CENTER);
topRow.add(addButton, BorderLayout.EAST);
add(topRow);
middleRow.add(multiplyLabel, BorderLayout.WEST);
middleRow.add(multiplyField, BorderLayout.CENTER);
middleRow.add(multiplyButton, BorderLayout.EAST);
add(middleRow);
bottomRow.add(totalLabel);
bottomRow.add(totalField);
bottomRow.add(stopButton);
add(bottomRow);
pack();
setVisible(true);
}
public class AddListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
String addFieldText = addField.getText();
String totalFieldText = totalField.getText();
double addAmount = Double.parseDouble(addFieldText);
double total = Double.parseDouble(totalFieldText);
total += addAmount;
totalField.setText(total + "");
}
}
//end class AddListener
public class StopListener implements ActionListener {//this is an inner class
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(theFrame, "You Clicked the stop button");
}//end class StopListener
}
public static void main(String[] args) {
JFrame newFrame = new BabyCalculator();
}
}
Note: The problem in the code is definitely related to the AddListener. Whenever I click the add button in the GUI I get an exception.

The problem is with the totalFieldText, it's default value is blank, meaning that when you try and convert to a double value, it causes a NumberFormatException
Try giving it a default value of 0, for example
totalField = new JTextField("0", 10);
You might also like to take a look at How to Use Spinners and How to Use Formatted Text Fields which will make your life easier

Uploading JPG Images in GUI Java?

So we randomly choose a number between 1 to 6 and whatever is rolled will have an image uploaded of a die face that corresponds to the number. It's compiling, but I get an exception thread I don't understand.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import java.util.Random;
import java.awt.FlowLayout;
public class Butttin {
private static JLabel label;
public static void main(String[] args) {
JFrame frame = new JFrame("Rolling Dice Game");
JPanel panel = new JPanel();
JButton buttonRoll = new JButton("Roll!");
buttonRoll.addActionListener(new buttonRoll());
panel.setLayout(new GridLayout(5, 2, 5, 5));
panel.add(label);
frame.setVisible(true);
frame.setSize(500, 500);
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(panel);
frame.pack();
}
private static class buttonRoll implements ActionListener {
private java.util.Random random = new java.util.Random();
public void actionPerformed(ActionEvent event) {
int max = 6;
int min = 1;
ImageIcon img;
int rolledNumber = random.nextInt(max - min + 1) + min;
String command = event.getActionCommand();
if (command == "Roll!") {
if ("Roll!".equals(command)) {
ImageIcon imageIcon = new ImageIcon("die 1.jpg");
label = new JLabel(imageIcon);
} else if (rolledNumber == 2){
ImageIcon imageIcon = new ImageIcon("die 2.jpg");
label = new JLabel(imageIcon);
} else if (rolledNumber == 3){
ImageIcon imageIcon = new ImageIcon("die 3.jpg");
label = new JLabel(imageIcon);
} else if (rolledNumber == 4){
ImageIcon imageIcon = new ImageIcon("die 4.jpg");
label = new JLabel(imageIcon);
} else if (rolledNumber == 5){
ImageIcon imageIcon = new ImageIcon("die 5.jpg");
label = new JLabel(imageIcon);
} else if (rolledNumber == 6){
ImageIcon imageIcon = new ImageIcon("die 6.jpg");
label = new JLabel(imageIcon);
}
}
}
}
}

The problem is that you do not initialize your JLabel before you add it to your JPanel. The easiest thing to do would be to initialize it directly:
private static JLabel label = new JLabel();
And in your actionPerformed method, instead of creating a new JLabel every time and replacing the old one, just use its setIcon method.
label.setIcon(imageIcon);
On another note, when working with Swing components (creating components, adding components, etc), it should be run on the Event Dispatch Thread:
javax.swing.SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
//...
}
});

Java Nesting Panels Transparency issue with alpha value

I'm a third grade computer engineer student and I'm trying to do a game project. I added a background image to my JFrame. And I tried to make the other panels transparent which I added to frame. I use alpha value for this, Ex: new Color(0,0,0,125). I olso use cardLayout in my program and for every calling a new segment or new page at the center panel; alphavalue takes the whole panels transparency and implement it to the selected panel and it creates a problem. Example : I have 7 buttons at left panel and when I click crimes button, crime panel comes to the center panel and left panel comes inside of center panel with buttons again(transparently).
I have 16 classes, so I only added main class.
Sorry for bad grammar. I hope you can understand me and help me.
import java.util.*;
import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.event.*;
public class TheMafia {
public static ImageIcon scale(ImageIcon i,int x,int y) {
Image img = i.getImage();
Image newimg = img.getScaledInstance(x,y,Image.SCALE_SMOOTH);
i = new ImageIcon(newimg);
return i;
}
public static void setButton (JButton b,int x,int y) {
b.setPreferredSize(new Dimension(x,y));
b.setBackground(Color.gray);
b.setForeground(Color.white);
b.setBorder(new LineBorder(Color.black,1));
b.setFont(new Font("Serif",Font.BOLD,18));
}
public static void main(String[] args) {
ImageIcon home2 = new ImageIcon("home.jpg");
home2 = scale(home2,1366,768);
JFrame theMafia = new JFrame();
theMafia.setTitle("The Mafia Game - Best game in the world!");
JPanel p1 = new JPanel();
JPanel p2 = new JPanel();
theMafia.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
theMafia.setContentPane(new JLabel(home2));
theMafia.setLayout(new BorderLayout());
//theMafia.setLayout(new FlowLayout());
//theMafia.setExtendedState(JFrame.MAXIMIZED_BOTH);
theMafia.setSize(800,700);
theMafia.setLocationRelativeTo(null);
theMafia.setVisible(true);
p1.setBackground(new Color(0,0,0,35));
p2.setBackground(new Color(0,0,0,65));
p1.setPreferredSize(new Dimension(250,150));
p2.setPreferredSize(new Dimension(250,150));
//theMafia.add(p1);
//theMafia.add(p2);
// kullanıcı oluşturuldu
User u1 = new User();
// suçlar oluşturuldu
Crime c1 = new Crime();
c1.setName("Yaşlı Kadın");
c1.setDifficulty(5);
c1.setStrength(1);
c1.setMoney(11);
Crime c2 = new Crime();
c2.setName("Dükkan Hırsızlığı");
c2.setDifficulty(10);
c2.setStrength(3);
c2.setMoney(67);
Crime c3 = new Crime();
c3.setName("Araba Hırsızlığı");
c3.setDifficulty(20);
c3.setStrength(6);
c3.setMoney(133);
// suçun seçilmesi
final JPanel crimes = new JPanel(new CardLayout());
//crimes.setBackground(new Color(0,0,0,65));
ImageIcon suçişle = new ImageIcon("suçişle.jpg");
suçişle = scale(suçişle,50,50);
JButton yap = new JButton("Suçu işle!",suçişle);
setButton(yap,100,65);
JPanel crime1 = new JPanel(new GridLayout(2,1));
crime1.setBackground(new Color(0,0,0,35));
crime1.setForeground(Color.white);
JLabel crime1Info = new JLabel("Suç : "+c1.getName()+"\n Para : "+c1.getMoney()+"\n Yapabilme ihtimali : "+c1.getCapable()+"\n Güç : "+c1.getStrength());
crime1Info.setFont(new Font("Serif",Font.BOLD,15));
crime1.add(crime1Info);
crime1.add(yap);
JPanel crime2 = new JPanel(new GridLayout(2,1));
crime2.setBackground(new Color(0,0,0,35));
crime2.setForeground(Color.white);
JLabel crime2Info = new JLabel("Suç : "+c2.getName()+"\n Para : "+c2.getMoney()+"\n Yapabilme ihtimali : "+c2.getCapable()+"\n Güç : "+c2.getStrength());
crime2Info.setFont(new Font("Serif",Font.BOLD,15));
crime2.add(crime2Info);
crime2.add(yap);
JPanel crime3 = new JPanel();
crime3.setBackground(new Color(0,0,0,35));
crime3.setForeground(Color.white);
JLabel crime3Info = new JLabel("Suç : "+c3.getName()+"\n Para : "+c3.getMoney()+"\n Yapabilme ihtimali : "+c3.getCapable()+"\n Güç : "+c3.getStrength());
crime2Info.setFont(new Font("Serif",Font.BOLD,15));
crime3.add(crime3Info);
crime3.add(yap);
crimes.add(crime1,c1.getName());
crimes.add(crime2,c2.getName());
crimes.add(crime3,c3.getName());
String crimesNames [] = {c1.getName(),c2.getName(),c3.getName()};
JComboBox crimesbox = new JComboBox(crimesNames);
crimesbox.setEditable(false);
crimesbox.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent evt) {
CardLayout cl = (CardLayout) (crimes.getLayout());
cl.show(crimes,(String)evt.getItem());
}
});
// menu
final JPanel menus = new JPanel(new CardLayout());
//menus.setBackground(new Color(0,0,0,35));
// crime
JPanel crime = new JPanel(new BorderLayout());
crime.setBackground(new Color(0,0,0,35));
crime.add(crimesbox,BorderLayout.PAGE_START);
crime.add(crimes,BorderLayout.SOUTH);
ImageIcon crimeimage = new ImageIcon("thief.png");
crimeimage = scale(crimeimage,50,50);
final JButton crimeButton = new JButton("Suçlar",crimeimage);
setButton(crimeButton,178,76);
crimeButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
CardLayout cl = (CardLayout) (menus.getLayout());
if (e.getSource() == crimeButton) {
cl.show(menus,"suç");
}
}
});
// weapon shop
JPanel weaponShop = new JPanel();
//weaponShop.setBackground(new Color(0,0,0,125));
final JButton weaponShopButton = new JButton("Silah Dükkanı");
setButton(weaponShopButton,178,76);
// building
JPanel buildingPanel = new JPanel();
//buildingPanel.setBackground(new Color(0,0,0,125));
final JButton buildingButton = new JButton("Binalar");
setButton(buildingButton,178,76);
// nightlife
JPanel nightLife = new JPanel();
//nightLife.setBackground(new Color(0,0,0,35));
final JButton nightLifeButton = new JButton("Gece Hayatı");
setButton(nightLifeButton,178,76);
// treatment center
JPanel treatmentCenter = new JPanel();
//treatmentCenter.setBackground(new Color(0,0,0,35));
final JButton treatmentCenterButton = new JButton("Tedavi Merkezi");
setButton(treatmentCenterButton,178,76);
// casino
JPanel casinoPanel = new JPanel();
//casinoPanel.setBackground(new Color(0,0,0,35));
final JButton casinoButton = new JButton("Gazino");
setButton(casinoButton,178,76);
// home page
JPanel home = new JPanel();
home.setBackground(new Color(0,0,0,35));
ImageIcon homeimage = new ImageIcon("home.jpg");
homeimage = scale(homeimage,1200,800);
JLabel homelabel= new JLabel();
home.add(homelabel);
ImageIcon homeicon = new ImageIcon("home_icon.png");
homeicon = scale(homeicon,50,50);
final JButton homeButton = new JButton("Home",homeicon);
setButton(homeButton,178,76);
homeButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
CardLayout cl = (CardLayout) (menus.getLayout());
if (e.getSource() == homeButton) {
cl.show(menus,"home");
}
}
});
menus.add(home,"home");
menus.add(crime,"suç");
menus.add(weaponShop,"silahDükkanı");
menus.add(buildingPanel,"bina");
menus.add(nightLife,"geceHayatı");
menus.add(treatmentCenter,"TedaviMerkezi");
menus.add(casinoPanel,"gazino");
Color grisi=new Color(13,13,13);
JPanel menusButton = new JPanel(new GridLayout(10,1));
//menusButton.setBackground(grisi);
menusButton.add(homeButton);
menusButton.add(crimeButton);
menusButton.add(weaponShopButton);
menusButton.add(buildingButton);
menusButton.add(nightLifeButton);
menusButton.add(treatmentCenterButton);
menusButton.add(casinoButton);
menusButton.setOpaque(false);
theMafia.add(menusButton,BorderLayout.WEST);
theMafia.add(menus,BorderLayout.CENTER);
}
}

Swing does not handle transparent background properly. Swing expects components to be either opaque or non-opaque and the transparency causes a problem because the component is neither.
Check out Background With Transparency for more information and a couple of solutions to solve the problem.

Java JFrame background color not working

I tried using:
frame1.getContentPane().setBackground(Color.yellow);
But it is not working. Can anyone help me?
import java.awt.*;
import java.awt.Color;
public class PlayGame {
public static void main(String[] args) {
GameFrame frame1 = new GameFrame();
frame1.getContentPane().setBackground(Color.yellow);
// Set Icon
Image icon = Toolkit.getDefaultToolkit().getImage("image/poker_icon.gif");
frame1.setIconImage(icon);
frame1.setVisible(true);
frame1.setSize(600, 700);
frame1.setTitle("Card Game");
// Set to exit on close
frame1.setDefaultCloseOperation(GameFrame.EXIT_ON_CLOSE);
}
}
GameFrame
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class GameFrame extends JFrame implements ActionListener {
private JPanel topPnl, btmPnl, pcPnl, mainPnl;
private JPanel titlePnl, playerPnl, computerPnl;
private JLabel titleLbl, playerLbl, computerLbl;
private JLabel testTextBox1, testTextBox2;
private ImageIcon playerIcon, computerIcon;
//
private JPanel pickCardPnl, pickCardTitlePnl, cardPnl, resultPnl, optionPnl;
private JLabel pickCardTitleLbl;
private JLabel card1Lbl, card2Lbl, card3Lbl, card4Lbl, card5Lbl;
private JLabel resultLbl;
private JButton restartBtn, showCardBtn, exitBtn;
private JButton card1Btn, card2Btn, card3Btn, card4Btn, card5Btn;
private ImageIcon card1Pic, card2Pic, card3Pic, card4Pic, card5Pic;
private JButton playerBtn, computerBtn;
private ImageIcon playerPic;
private String[] card = new String[53];
private String name;
// ArrayInt al;
public GameFrame() {
// a1 = new Array();
//a1.generateRandom();
setCard();
setName();
// Top Panel /////////////////////////////////////
mainPnl = new JPanel(new BorderLayout());
topPnl = new JPanel(new BorderLayout(50, 0));
titlePnl = new JPanel();
pcPnl = new JPanel(new GridLayout(1, 2, 10, 10));
playerPnl = new JPanel(new BorderLayout(10, 10));
computerPnl = new JPanel(new BorderLayout(10, 10));
// Title Panel
titleLbl = new JLabel("Card Game");
titlePnl.add(titleLbl);
// Player Panel
playerIcon = new ImageIcon("image/player.png");
playerLbl = new JLabel(name, playerIcon, JLabel.CENTER);
playerPnl.add(playerLbl, BorderLayout.NORTH);
playerPic = new ImageIcon("image/unknwon.png");
playerBtn = new JButton(playerPic);
playerPnl.add(playerBtn, BorderLayout.CENTER);
playerBtn.setContentAreaFilled(false);
playerBtn.setBorder(BorderFactory.createEmptyBorder());
// Computer Panel
computerIcon = new ImageIcon("image/computer.png");
computerLbl = new JLabel("Computer:", computerIcon, JLabel.CENTER);
computerPnl.add(computerLbl, BorderLayout.NORTH);
playerPic = new ImageIcon("image/back.png");
computerBtn = new JButton(playerPic);
computerPnl.add(computerBtn, BorderLayout.CENTER);
computerBtn.setContentAreaFilled(false);
computerBtn.setBorder(BorderFactory.createEmptyBorder());
pcPnl.add(playerPnl);
pcPnl.add(computerPnl);
// Add panel into Top Panel
topPnl.add(titlePnl, BorderLayout.NORTH);
topPnl.add(pcPnl, BorderLayout.CENTER);
// Bottom Panel /////////////////////////////////////
btmPnl = new JPanel(new BorderLayout());
pickCardPnl = new JPanel(new BorderLayout());
pickCardTitlePnl = new JPanel();
cardPnl = new JPanel(new GridLayout(1, 5, 5, 5));
resultPnl = new JPanel();
optionPnl = new JPanel(new GridLayout(1, 3, 5, 5));
// Pick Card Panel
pickCardTitleLbl = new JLabel("Pick Your Card:");
pickCardPnl.add(pickCardTitleLbl, BorderLayout.NORTH);
card1Pic = new ImageIcon(card[1]);
card1Btn = new JButton(card1Pic);
cardPnl.add(card1Btn);
card1Btn.addActionListener(this);
card2Pic = new ImageIcon(card[2]);
card2Btn = new JButton(card2Pic);
cardPnl.add(card2Btn);
card2Btn.addActionListener(this);
card3Pic = new ImageIcon(card[3]);
card3Btn = new JButton(card3Pic);
cardPnl.add(card3Btn);
card3Btn.addActionListener(this);
card4Pic = new ImageIcon(card[4]);
card4Btn = new JButton(card4Pic);
cardPnl.add(card4Btn);
card4Btn.addActionListener(this);
card5Pic = new ImageIcon(card[5]);
card5Btn = new JButton(card5Pic);
cardPnl.add(card5Btn);
card5Btn.addActionListener(this);
// new ImageIcon(a1.getRandomNumber);
pickCardPnl.add(cardPnl, BorderLayout.CENTER);
card1Btn.setContentAreaFilled(false);
card1Btn.setBorder(BorderFactory.createEmptyBorder());
card2Btn.setContentAreaFilled(false);
card2Btn.setBorder(BorderFactory.createEmptyBorder());
card3Btn.setContentAreaFilled(false);
card3Btn.setBorder(BorderFactory.createEmptyBorder());
card4Btn.setContentAreaFilled(false);
card4Btn.setBorder(BorderFactory.createEmptyBorder());
card5Btn.setContentAreaFilled(false);
card5Btn.setBorder(BorderFactory.createEmptyBorder());
// Result Panel
setCard();
resultLbl = new JLabel("adasdadadasdasdasdasd");
resultPnl.add(resultLbl);
// Option Panel
restartBtn = new JButton("Restart");
optionPnl.add(restartBtn);
restartBtn.addActionListener(this);
showCardBtn = new JButton("Show Cards");
optionPnl.add(showCardBtn);
showCardBtn.addActionListener(this);
exitBtn = new JButton("Exit");
optionPnl.add(exitBtn);
exitBtn.addActionListener(this);
// Add panel into Bottom Panel
btmPnl.add(pickCardPnl, BorderLayout.NORTH);
btmPnl.add(resultPnl, BorderLayout.CENTER);
btmPnl.add(optionPnl, BorderLayout.SOUTH);
//
mainPnl.add(topPnl, BorderLayout.NORTH);
// add(midPNL, BorderLayout.CENTER);
mainPnl.add(btmPnl, BorderLayout.CENTER);
add(mainPnl);
// Menu bar
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Game");
menuBar.add(menu);
JMenuItem item3 = new JMenuItem("Change Name");
item3.addActionListener(this);
menu.add(item3);
JMenuItem item = new JMenuItem("Change Card Deck");
item.addActionListener(this);
menu.add(item);
JMenu subMenu = new JMenu("Change BackGround");
subMenu.addActionListener(this);
menu.add(subMenu);
JMenuItem subItem = new JMenuItem("Blue");
subItem.addActionListener(this);
subMenu.add(subItem);
JMenuItem subItem2 = new JMenuItem("Green");
subItem2.addActionListener(this);
subMenu.add(subItem2);
//
menu.addSeparator();
//
JMenuItem item4 = new JMenuItem("Quit");
item4.addActionListener(this);
menu.add(item4);
setJMenuBar(menuBar);
} //End of GameFrame
public void setCard() {
GenRandom g1 = new GenRandom();
g1.GenRandomCard();
int[] allCard = new int[11];
allCard = g1.getAllCard();
for (int i = 1; i <= 10; i++) {
card[i] = "image/card/" + allCard[i] + ".png";
}
}
public void setName() {
// name = JOptionPane.showInputDialog(null, "Please Enter Your Name", "Welcome", JOptionPane.QUESTION_MESSAGE) + ":";
}
public void actionPerformed(ActionEvent e) {
if (e.getSource() == card1Btn) {
playerBtn.setIcon(card1Pic);
card1Btn.setEnabled(false);
}
if (e.getSource() == card2Btn) {
playerBtn.setIcon(card2Pic);
card2Btn.setEnabled(false);
}
if (e.getSource() == card3Btn) {
playerBtn.setIcon(card3Pic);
card3Btn.setEnabled(false);
}
if (e.getSource() == card4Btn) {
playerBtn.setIcon(card4Pic);
card4Btn.setEnabled(false);
}
if (e.getSource() == card5Btn) {
playerBtn.setIcon(card5Pic);
card5Btn.setEnabled(false);
}
if (e.getSource() == restartBtn) {
new AePlayWave("sound/jet.wav").start();
JOptionPane.showMessageDialog(null, "Restart Button ");
}
if (e.getSource() == exitBtn) {
/* long start = System.currentTimeMillis();
long end = start + 4 * 1000; // 60 seconds * 1000 ms/sec
while (System.currentTimeMillis() < end) {
// run
new AePlayWave("sound/jet.wav").start();
}*/
System.exit(0);
}
}
}

Since you did not post an SSCCE, I will do it for you. This shows how to change the background color of a JFrame. Starting from this, you can start adding components to the JFrame and see where you go wrong, instead of letting us look at a few hundred lines of code.
import javax.swing.JFrame;
import java.awt.Color;
import java.awt.EventQueue;
public class ColoredFrame {
public static void main( String[] args ) {
EventQueue.invokeLater( new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame( "TestFrame" );
frame.getContentPane().setBackground( Color.PINK );
//frame contains nothing, so set size
frame.setSize( 200, 200 );
frame.setVisible( true );
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
}
} );
}
}

Just put your setVisible(true); at the end of your constructor.
Moreover you had added mainPnl on your JFrame, so changing colour of the JFrame will be useless,
so instead of writing
add(mainPnl);
in your GameFrame class, you better be using
setContentPane(mainPnl);
for frame1.getContentPane().setBackground(Color.YELLOW); to work.
Hope this might help
Regards

You should give background color to JPanel and then use this JPanel in your JFrame rather than giving direct background to your JFrame.

I know this is a very old question, but for others that are looking for the right answer this could also be written as following:
frame1.getContentPane().setBackground(new Color (255,255,102)); //or whatever color you want in the RGB range