How to compare the Public String [] value

[taurus22]

Hi guys,
i want to make a program in which i write the Months Strings via while into the checkbox.
I already did that but i have also to add an day if February is a loop day.

So my question is how to say java that if Months is equal to February & year is a leap year, add 1. (i didn't wrote the year code because it's not relevant for my problem.)

Here is my code:

public String[] Months ={"January","February","March","April","May", "June", "July", "August", "September", "Oktober", "November", "December"};
    public Asg1KeapYear() {
        initComponents();
         int MonthNo = 0;
while (MonthNo < Months.length) 
     {
	cbxMonth.addItem(Months[MonthNo]);
	 MonthNo = MonthNo + 1;
     }

The problem starts here: by Months.equals.

if  (((Months.equals ("February")) && (year % 400 == 0)) ||
    ((year % 4 == 0) && (year % 100 != 0)))
       {
       monthNum = monthNum + 1;
       }

Thank you in advance :)

EDIT: Netbeans shows me .equals() on incompatible types on Months.equals, do i have to declare it somehow?

[jim829]

What exactly is monthNum? Based on your supplied code, it is unclear why you need to check if the month
is February. You need to determine if the year is a leap year and then modify the number of days associated
with February.

Regards,
Jim

[taurus22]

i made also an array for the number of the days, monthNum is the solution. For example January has 31 days.

Here is the Code for that:

int[] monthNumber = {31, 28, 31, 30, 31, 30 , 31 , 31 , 30 , 31 ,30 ,31};
       int month = cbxMonth.getSelectedIndex();
       int monthNum = monthNumber[month];

I'm pretty sure i have to do it like that because the instruction is: If the month chosen is February, and the year chosen is a leap year, add 1 to the number of days for that month.

However thank you for your help

[jim829]

Then you don't need to compare to February. You already know that the number of days for February is index number 1. So
after you determine that the year is a leap year, just increment the appropriate number of days.

monthNumber[1]++;

Regards,
Jim

[taurus22]

Ah Thank you I'll try it :)

EDIT

It still shows me 28 days, this is the full code.

public class Asg1KeapYear extends javax.swing.JFrame {

  public String[] Months ={"January","February","March","April","May", "June", "July", "August", "September", "Oktober", "November", "December"};
    public Asg1KeapYear() {
        initComponents();
         int MonthNo = 0;
while (MonthNo < Months.length) 
     {
	cbxMonth.addItem(Months[MonthNo]);
	 MonthNo = MonthNo + 1;
     }
int year=1800;
while(year<2014)
{
cbxYear.addItem(year + 1);
year = year + 1;
}
    }

EDIT: I pasted the wrong code in I meant this: This was your solution right? I was in hurry sorry :)

int[] monthNumber = {31, 28, 31, 30, 31, 30 , 31 , 31 , 30 , 31 ,30 ,31};
       int month = cbxMonth.getSelectedIndex();
       int monthNum = monthNumber[month];
       int year = cbxYear.getSelectedIndex();
       if ((year % 400 == 0) || ((year % 4 == 0) && (year % 100 != 0)))
       {
        monthNumber[1]++;
       }
          
        txtResult.setText(monthNum + "" );
 }

[Norm]

this is the full code

Not sure what that means.
Could you arrange the code so it could be copied, compiled and executed for testing?

[taurus22]

Not sure what that means.
Could you arrange the code so it could be copied, compiled and executed for testing?

monthNumber[1]++;

maybe this will work but i recognized that even

monthNum = monthNum + 1

will not add + 1 to leap years.
I think there is a problem with comparing the year. I wrote the code with a loop which is below to get the years and months within the program and it works fine, but it doesn't work when i try comparing if year is a leap year or not.
So i can't compare the year from while with only

int years = cbxYear.getSelectedIndex();

Does somebody have a solution? :)

Sorry for my bad english

public class Asg1KeapYear extends javax.swing.JFrame {
 
  public String[] Months ={"January","February","March","April","May", "June", "July", "August", "September", "Oktober", "November", "December"};
    public Asg1KeapYear() {
        initComponents();
         int MonthNo = 0;
while (MonthNo < Months.length)
     {
    cbxMonth.addItem(Months[MonthNo]);
     MonthNo = MonthNo + 1;
     }
int year=1800;
while(year<2014)
{
cbxYear.addItem(year + 1);
year = year + 1;
}
    }

[Norm]

Please edit your post and wrap your code with code tags:
[code]
YOUR CODE GOES HERE
[/code]
to get highlighting and preserve formatting.

it doesn't work when i try comparing if year is a leap year or not.

What does "doesn't work" mean?
It never finds a leap year?
It finds the wrong year as a leap year?
It sometimes finds a leap year but misses other years?

Have you tried debugging the code to see what it is doing wrong?

[taurus22]

If i put in

monthNumber[1]++

nothing happens. But if i put in

MonthNo = MonthNo + 1;

which was only to try if leap years are adding one. Some none leap years like 1805 will get + 1 in months but not all of them.

[Norm]

If i put in
monthNumber[1]++
nothing happens.

Are you saying that the element at index 1 is not incremented? It will be incremented if that code is executed.

You need to post complete code that will compile, execute and show the problem. It is not possible to see what is wrong with only one line of code.

If the problem is with the leap year detection code, you need to write a special purpose testing program for debugging that code.

[taurus22]

Yeah i know but it doesn't increment. This is the complete code, made with netbeans

public class Asg1KeapYear extends javax.swing.JFrame {

  public String[] Months ={"January","February","March","April","May", "June", "July", "August", "September", "Oktober", "November", "December"};
    public Asg1KeapYear() {
        initComponents();
         int MonthNo = 0;
while (MonthNo < Months.length) 
     {
      cbxMonth.addItem(Months[MonthNo]);
	 MonthNo = MonthNo + 1;
     }
int year =1800;
while(year<2014)
{
cbxYear.addItem(year + 1);
year = year + 1;
}
                           }

 private void btnCalculateActionPerformed(java.awt.event.ActionEvent evt) {                                             
      
     

       int[] monthNumber = {31, 28, 31, 30, 31, 30 , 31 , 31 , 30 , 31 ,30 ,31};
       int month = cbxMonth.getSelectedIndex();
       int monthNum = monthNumber[month];
       int years = cbxYear.getSelectedIndex();
       
       if ((years % 400 == 0) || ((years % 4 == 0) && (years % 100 != 0)))
       {
        monthNumber[1]++;
       }
          
        txtResult.setText(monthNum + "" );
                                                                                                      }

and this is how the GUI looks

[jim829]

Yeah i know but it doesn't increment. This is the complete code, made with netbeans

That is not the complete code. Where are your cbx variables? Where's the code that displays the dialog windows?

Regards,
Jim

[taurus22]

aren't these the cbx variables?

   public String[] Months ={"January","February","March","April","May", "June", "July", "August", "September", "Oktober", "November", "December"};
    public Asg1KeapYear() {
        initComponents();
         int MonthNo = 0;
while (MonthNo < Months.length) 
     {
      cbxMonth.addItem(Months[MonthNo]);
	 MonthNo = MonthNo + 1;
     }
int year =1800;
while(year<2014)
{
cbxYear.addItem(year + 1);
year = year + 1;
}
                           }


}

regards taurus

[jim829]

Where are they declared? Where is your initComponents() method? Where do you add the Dialogs to the JFrame?
Normally, we don't want all the code but you aren't showing us enough to help you solve the problem.

Regards,
Jim

[taurus22]

Oh you want everything? Even things that are standard? Then here

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

package taulantasg1;

/**
 *
 * @author Taulant
 */
public class Asg1KeapYear extends javax.swing.JFrame {

  public String[] Months ={"January","February","March","April","May", "June", "July", "August", "September", "Oktober", "November", "December"};
    public Asg1KeapYear() {
        initComponents();
         int MonthNo = 0;
while (MonthNo < Months.length) 
     {
      cbxMonth.addItem(Months[MonthNo]);
	 MonthNo = MonthNo + 1;
     }
int year =1800;
while(year<2014)
{
cbxYear.addItem(year + 1);
year = year + 1;
}
                           }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        btnCalculate = new javax.swing.JButton();
        jLabel2 = new javax.swing.JLabel();
        txtResult = new javax.swing.JTextField();
        cbxMonth = new javax.swing.JComboBox();
        cbxYear = new javax.swing.JComboBox();
        jLabel3 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Taulant's leap year checker");

        jLabel1.setFont(new java.awt.Font("Tahoma", 0, 14)); // NOI18N
        jLabel1.setText("Month:");

        btnCalculate.setText("Calculate...");
        btnCalculate.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnCalculateActionPerformed(evt);
            }
        });

        jLabel2.setFont(new java.awt.Font("Tahoma", 0, 14)); // NOI18N
        jLabel2.setText("Result:");

        txtResult.setForeground(new java.awt.Color(255, 0, 0));

        jLabel3.setFont(new java.awt.Font("Tahoma", 0, 14)); // NOI18N
        jLabel3.setText("Year:");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(43, 43, 43)
                        .addComponent(jLabel2))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(32, 32, 32)
                        .addComponent(jLabel1)))
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 85, Short.MAX_VALUE)
                        .addComponent(txtResult, javax.swing.GroupLayout.PREFERRED_SIZE, 242, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(22, 22, 22))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(45, 45, 45)
                        .addComponent(cbxMonth, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addComponent(jLabel3)
                        .addGap(37, 37, 37)
                        .addComponent(cbxYear, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(64, 64, 64))))
            .addGroup(layout.createSequentialGroup()
                .addGap(32, 32, 32)
                .addComponent(btnCalculate)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(26, 26, 26)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1)
                    .addComponent(cbxMonth, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(cbxYear, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jLabel3))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(btnCalculate)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 17, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel2)
                    .addComponent(txtResult, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(30, 30, 30))
        );

        pack();
    }// </editor-fold>                        

    private void btnCalculateActionPerformed(java.awt.event.ActionEvent evt) {                                             
      

       int[] monthNumber = {31, 28, 31, 30, 31, 30 , 31 , 31 , 30 , 31 ,30 ,31};
       int month = cbxMonth.getSelectedIndex();
       int monthNum = monthNumber[month];
       int years = cbxYear.getSelectedIndex();
       
       if ((years % 400 == 0) || ((years % 4 == 0) && (years % 100 != 0)))
       {
        monthNumber[1]++;
       }
          
        txtResult.setText(monthNum + "" );
         
    










     
	

    }                                            

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see [url=http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html]How to Set the Look and Feel (The Javaâ„¢ Tutorials > Creating a GUI With JFC/Swing > Modifying the Look and Feel)[/url] 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(Asg1KeapYear.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Asg1KeapYear.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Asg1KeapYear.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Asg1KeapYear.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Asg1KeapYear().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton btnCalculate;
    private javax.swing.JComboBox cbxMonth;
    private javax.swing.JComboBox cbxYear;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JTextField txtResult;
    // End of variables declaration                   
}

Regards Taurus

[jim829]

Ok, now I know what the problems are:

First, now that I see what is going on, you do need to check the month. But use the index instead of the name.
Second, you can use monthNum instead of the way I told you because that is what you are setting in the dialog.
Just add 1 to monthNum like you did before. I will post that code since I contributed to doing it another way.

if (month == 1 && ((years % 400 == 0) || ((years % 4 == 0) && (years % 100 != 0)))) {
         monthNum++;
}

txtResult.setText(monthNum + "");

The real problem is in your year (you should have printed it out to make certain you were retrieving the year).
What you are getting is the index of the year in the combo box. So you need to add the base year to the index
to get the actual year. Your base year is 1801 so add that to years.

In the future you should sprinkle print statements throughout your code to verify your variables. It is the basic
and most powerful debugging tool I know.

Regards,
Jim

[JosAH]

[CODE]
int years = cbxYear.getSelectedIndex();

If you select year, say, 1801, the selected will be 0 (which is not a year).

kind regards,

Jos

[Norm]

As Jim said, printing the value of years would have shown you what the code was doing.

[jim829]

And a couple more things regarding JComboBoxes.

1. JComboBox is a generic type so you should specify the type of the values.

cbxMonth = new javax.swing.JComboBox<Integer>();
cbxYear = new javax.swing.JComboBox<Integer>();

2. It would have been better to use cbxYear.getSelectedItem(). Then you
don't need to worry about the base year as you are now getting the
selected year.

Regards,
Jim

[taurus22]

Thank you very much, it works now with :)

int years = (int) cbxYear.getSelectedItem();