ComboBox help


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Thread: ComboBox help

  1. #1
    Join Date
    Feb 2009
    Posts
    3

    ComboBox help

    I am trying to add a drop down combo box for my program but I am having trouble adding items to the combo box. can anyone tell me what i am doing wrong or what I need to add/change.
    Code:
    //imports required packages
    import java.awt.*;                      //to create buttons
    import javax.swing.*;                   //imports java swing
    import java.awt.event.ActionEvent;      //imports event action events
    import java.awt.event.ActionListener;   //imports event action listener for the event
    import java.text.DecimalFormat;         //to import decimal format for money
    
    class mortgageCalculatorMcCabe3 extends JFrame implements ActionListener {
    
    	//Fields for user input
    	JTextField principalAmount = new JTextField(15);
    	JTextField yearlyInterestRate = new JTextField(15);
    	JTextField numberOfYears = new JTextField(15);
    	JTextField monthlyPayments = new JTextField(15);
    	JLabel validateLabel = new JLabel();
    	public JComboBox MortIntRate;
    
    	/*Declaring and initializing variables*/
    	int term = 0;
    	double principleAmount = 0;
    	String ArrayTerm [] = {"7", "15", "30"};
    	String ArrayInterestRate [] = {"5.35", "5.5", "5.75"};
    
    mortgageCalculatorMcCabe3() {
    	
    	//Sets the title at the top of program 
    	super("Ryan's Mortgage Calculator");	
    	
    	Panel comboBox = new Panel();
    	JComboBox interestRateList, termList;
    	   
    	//Sets the size of the Frame
    	setSize(350, 225);
    	setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    	Container pane = getContentPane();
    	FlowLayout flow = new FlowLayout(FlowLayout.RIGHT);
    	pane.setLayout(flow);
    
    	//Creates Labels and Fields for row 1 
    	JPanel row1 = new JPanel();
    	JLabel principalLabel = new JLabel("Loan Amount:");
    	row1.add(principalLabel);
    	row1.add(principalAmount);
    	pane.add(row1);
    	
    	//Creates Labels and Fields for row 2
    	JPanel row2 = new JPanel();
    	JLabel numYearsLabel = new JLabel("Term of Loan(Years):");
    	row2.add(numYearsLabel);
    	row2.add(numberOfYears);
    	pane.add(row2);
    
    	////Creates Labels and Fields for row 3
    	JPanel row3 = new JPanel();
    	JLabel yearIntrateLabel = new JLabel("Interest Rate:");
    	row3.add(yearIntrateLabel);
    	row3.add(yearlyInterestRate);
    	pane.add(row3);
    
    	////Creates Labels and Fields for row 4
    	JPanel row4 = new JPanel();
    	JLabel monthlyPaymentsLabel = new JLabel("Total Monthly Payment:");
    	row4.add(monthlyPaymentsLabel);
    	row4.add(monthlyPayments);
    	pane.add(row4);
    	setContentPane(pane);
    	setVisible(true);
    
    	//Creates Labels and Fields for row 5
    	JPanel row5 = new JPanel();
    	JButton calculate = new JButton("Calculate");
    	calculate.addActionListener(this);
    	row5.add(calculate);
    	pane.add(row5);
    	JButton reset = new JButton("Clear");
    	reset.addActionListener(this);
    	row5.add(reset);
    	pane.add(row5);
    	JButton exit = new JButton("Exit");
    	exit.addActionListener(this);
    	row5.add(exit);
    	pane.add(row5);
    	
    	termList = new JComboBox(ArrayTerm);
    	termList.setSelectedIndex(0);
    	termList.addItemListener(this);
    		
    
    		interestRateList = new JComboBox(ArrayInterestRate);
    		interestRateList.setSelectedIndex(0);
    		interestRateList.addItemListener(this);		
    
    		/*Setup list*/
    		comboBox.add(loanTerm);
    		comboBox.add(termList);		
    		comboBox.add(loanInterest);
    		comboBox.add(interestRateList);
    		
    }
    //This parts performs the Actions for the Calculate, Clear & Exit buttons
    public void actionPerformed(ActionEvent event) {
    	String command = event.getActionCommand();
    		if (command == "Calculate")
    			compute();
    
    		if (command == "Clear")
    			clearAllFields();
    		
    		if (command == "Exit")
    			exit();}
    
    void compute()
    {
    
    	try{
    
    		validateLabel.setText("");
    		validateLabel.validate();
    
    	Double yearIntrate = new Double (yearlyInterestRate.getText());
    	Double principal = new Double (principalAmount.getText());
    	Integer numYears = new Integer (numberOfYears.getText());
    
    	double payFreq = 12;
    	double interestRateMonths;
    	double monthlyPayment;
    	double numPayments;
    
    //results and formula's
    interestRateMonths = (yearIntrate.doubleValue() / 100) / payFreq;
    numPayments = payFreq * numYears.intValue();
    
    double temp = Math.pow(1 + interestRateMonths, (-1*numPayments));
    monthlyPayment = principal.doubleValue() * interestRateMonths / (1 - (temp));
    
    //Format used to set two decimal places.
    DecimalFormat currency = new DecimalFormat("$0.00");
    
    monthlyPayments.setText(currency.format(monthlyPayment));
    
    //if user submit non valid information it provides an error.
    } catch(Exception error)
    {
    validateLabel.setText("Invalid Entry! Try again.");
    }
    }
    
    //to clear the fields back to beginning
    void clearAllFields(){
    	principalAmount.setText("");
    	yearlyInterestRate.setText("");
    	numberOfYears.setText("");
    	monthlyPayments.setText("");
    }
    //exit program
    void exit(){
    	System.exit(0);
    
    }
    
    public static void main(String[] arguments)
    {
    mortgageCalculatorMcCabe3 mortgageCalculatorMcCabe3 = new mortgageCalculatorMcCabe3 ();
          }
    }//end program
    Last edited by Hack; 02-26-2009 at 09:49 AM. Reason: Added Code Tags

  2. #2
    Join Date
    Mar 2007
    Location
    Bangalore, India
    Posts
    247
    What did you do to add items, and what error did you get?

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