I am attempting to create a basic grid layout in a tabbed pane with a menu bar.
The menu bar will have a basic File JMenu with an exit menuItem and a Color JMenu that will change the color of the font and background color.
One tab will calculate the PMT function as used in Excel.
The second tab will calculate Future Value as used in Excel.
The Final Tab is a simple help layout.
When trying to view the layout and basic functionality i receive a NullPointerException. The Exception seems to be called at line 208 ( which is where the TextArea will display the calculations for the PMT function ) at line 52 ( which is where createPage1() is called ) and at line 263 ( which is where mainframe is instantiated as Finance ).
The last of which i don't truly understand it purpose nor its functionality. This is a work in progress and no formulas have been added nor have all the actionListeners been added. The only thing I want now is to be able to view the Layout.
public class Finance extends JFrame{
private JTabbedPane tabPane;
private JPanel panel1;
private JPanel panel2;
private JPanel panel3;
private JMenuBar menuBar;
private JMenu fileMenu;
private JMenu colorMenu;
private JMenuItem exitItem;
private JRadioButtonMenuItem blueItem;
private JRadioButtonMenuItem blackItem;
private JRadioButtonMenuItem redItem;
private JRadioButtonMenuItem whiteItem;
private JRadioButtonMenuItem defItem;
private JButton calc1;
private JButton calc2;
TextArea text;
public Finance(){
setTitle("Finance");
setBackground(Color.GRAY);
JPanel topPanel = new JPanel();
topPanel.setLayout(new BorderLayout());
getContentPane().add(topPanel);
createPage1();
createPage2();
createPage3();
tabPane = new JTabbedPane();
tabPane.addTab("Loan Payment", panel1);
tabPane.addTab("Future Value", panel2);
tabPane.addTab("Help", panel3);
topPanel.add(tabPane, BorderLayout.CENTER);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
buildMenuBar();
pack();
}
public void buildMenuBar(){
menuBar = new JMenuBar();
buildFileMenu();
buildColorMenu();
menuBar.add(fileMenu);
menuBar.add(colorMenu);
setJMenuBar(menuBar);
}
public void buildFileMenu(){
exitItem = new JMenuItem("Exit");
exitItem.setMnemonic(KeyEvent.VK_X);
exitItem.addActionListener(new ExitListener());
// Create a JMenu object for the File menu.
fileMenu = new JMenu("File");
fileMenu.setMnemonic(KeyEvent.VK_F);
// Add the Exit menu item to the File menu.
fileMenu.add(exitItem);
}
public void buildColorMenu(){
defItem = new JRadioButtonMenuItem("Deafult", true);
defItem.setMnemonic(KeyEvent.VK_D);
defItem.addActionListener(new ColorListener());
blueItem = new JRadioButtonMenuItem("Blue");
blueItem.setMnemonic(KeyEvent.VK_B);
blueItem.addActionListener(new ColorListener());
blackItem = new JRadioButtonMenuItem("Black");
blackItem.setMnemonic(KeyEvent.VK_L);
blackItem.addActionListener(new ColorListener());
whiteItem = new JRadioButtonMenuItem("White");
whiteItem.setMnemonic(KeyEvent.VK_W);
whiteItem.addActionListener(new ColorListener());
redItem = new JRadioButtonMenuItem("Red");
redItem.setMnemonic(KeyEvent.VK_R);
redItem.addActionListener(new ColorListener());
ButtonGroup group = new ButtonGroup();
group.add(blueItem);
group.add(blackItem);
group.add(whiteItem);
group.add(redItem);
colorMenu = new JMenu("Color");
colorMenu.setMnemonic(KeyEvent.VK_C);
colorMenu.add(defItem);
colorMenu.addSeparator();
colorMenu.add(blueItem);
colorMenu.add(blackItem);
colorMenu.add(whiteItem);
colorMenu.add(redItem);
}
private class ExitListener implements ActionListener{
public void actionPerformed(ActionEvent e){
System.exit(0);
}
}
private class ColorListener implements ActionListener{
public void actionPerformed(ActionEvent e){
if(blackItem.isSelected()){
panel1.setForeground(Color.WHITE);
panel2.setForeground(Color.WHITE);
panel3.setForeground(Color.WHITE);
panel1.setBackground(Color.BLACK);
panel2.setBackground(Color.BLACK);
panel3.setBackground(Color.BLACK);
}
else if(redItem.isSelected()){
panel1.setForeground(Color.WHITE);
panel2.setForeground(Color.WHITE);
panel3.setForeground(Color.WHITE);
panel1.setBackground(Color.RED);
panel2.setBackground(Color.RED);
panel3.setBackground(Color.RED);
}
else if(whiteItem.isSelected()){
panel1.setForeground(Color.BLACK);
panel2.setForeground(Color.BLACK);
panel3.setForeground(Color.BLACK);
panel1.setBackground(Color.WHITE);
panel2.setBackground(Color.WHITE);
panel3.setBackground(Color.WHITE);
}
else if(blueItem.isSelected()){
panel1.setForeground(Color.WHITE);
panel2.setForeground(Color.WHITE);
panel3.setForeground(Color.WHITE);
panel1.setBackground(Color.BLUE);
panel2.setBackground(Color.BLUE);
panel3.setBackground(Color.BLUE);
}
else if(defItem.isSelected()){
panel1.setForeground(Color.GRAY);
panel2.setForeground(Color.GRAY);
panel3.setForeground(Color.GRAY);
panel1.setBackground(Color.BLACK);
panel2.setBackground(Color.BLACK);
panel3.setBackground(Color.BLACK);
}
}
}
public void createPage1(){
panel1 = new JPanel();
panel1.setLayout(new GridLayout(5, 2));
calc1 = new JButton("Calculate Payments");
JTextField loan = new JTextField();
JTextField months = new JTextField();
JTextField irp1 = new JTextField();
JTextField pymnt = new JTextField();
text = new TextArea();
panel1.add(new JLabel("Loan Amount:"));
panel1.add(loan);
panel1.add(new JLabel("Payment Length in Months:"));
panel1.add(months);
panel1.add(new JLabel("Interest Rate Percentage:"));
panel1.add(irp1);
panel1.add(new JLabel("Payment Amount (Fixed):"));
panel1.add(pymnt);
panel1.add(calc1);
panel2.add(text);
}
public void createPage2(){
panel2 = new JPanel();
panel2.setLayout(new GridLayout(5,2));
calc2 = new JButton("Calculate Future Value");
JTextField length = new JTextField();
JTextField value = new JTextField();
JTextField monthly = new JTextField();
JTextField irp2 = new JTextField();
JTextField fv = new JTextField();
panel2.add(new JLabel("Initial Value:"));
panel2.add(value);
panel2.add(new JLabel("Monthly Contribution:"));
panel2.add(monthly);
panel2.add(new JLabel("Interest Rate Percentage:"));
panel2.add(irp2);
panel2.add(new JLabel("Length in Years:"));
panel2.add(length);
panel1.add(calc2);
panel2.add(fv);
}
public void createPage3(){
panel3 = new JPanel();
panel3.setLayout(new GridLayout(3,3));
JButton button1 = new JButton("Input");
JButton button2 = new JButton("Output");
JButton button3 = new JButton("Input");
JButton button4 = new JButton("Output");
JButton button5 = new JButton("Navigation");
JButton button6 = new JButton("Information");
panel3.add(new JLabel("Loan Payment:"));
panel3.add(button1);
panel3.add(button2);
panel3.add(new JLabel("Future Value:"));
panel3.add(button3);
panel3.add(button4);
panel3.add(new JLabel("Basic Info:"));
panel3.add(button5);
panel3.add(button6);
}
public static void main(String args[]){
@SuppressWarnings("unused")
Finance mainFrame = new Finance();
}
The complete output is as follows:
Exception in thread "main" java.lang.NullPointerException
at Finance.createPage1(Finance.java:208)
at Finance.<init>(Finance.java:52)
at Finance.main(Finance.java:263)
All Help is welcome and appreciated. I am more looking for the reason of the error and general ways to fix it than for a specific solution. Feel free to be as judgmental of the coding as you wish, but if something can be simplified or altered please comment on how to do so.
