CODEWITHSUNDEEP
javadatecalendar
Edgars
Edgars

Reputation: 953

How to output all months between begining of period and the end of the period. using Calendar class

I am creating programm that uses this class to retrieve current date. In order to work with that I need to get back some time in past. For example, today is 3.11.2013 user selects 18 month period, so I am using this code:

Calendar ca =Calendar.getInstance();
ca.add(Calendar.MONTH, -n);

Where the n variable stands for user input (months). Works great. But now I want to retrieve each month and show that on screen like this:

September,2012
October,2012
.....
.....
November, 2013

I tried to create loop, but I can't understand how I can realy make for each loop run add 1 month to start date. Update:

int i =0;
    Calendar ca =Calendar.getInstance();//iegūstam pašreizējo laiku
    ca.add(Calendar.MONTH, -n);
    ca.set(Calendar.DAY_OF_MONTH, 1);

while (i<n)
        {


            int month_n = ca.get(Calendar.MONTH);   
            int year_n = ca.get(Calendar.YEAR);

            try {//iegūstam datus ko rakstīt failā
                //record.setDate(5);//uzstādam vērtības
                record.setIncome(input.nextDouble());
                record.setAtv(atv_sum);
                record.setSumAtv(atv_sum+45.00);
                double iedz=(((record.getIncome()-record.getSumAtv())/100)*24);//iedz ienakuma nodoklis
                double soc_apd=(((record.getIncome()-record.getSumAtv())/100)*11);//sociālās apdr.nodoklis
                double netto =record.getIncome()-(iedz+soc_apd);

            if(record.getIncome()>0){
                    output.format("%-10s%-20s%-20s%-20s%-20s%-20s%-20s%-20s\n",
                                year_n,
                                month_n,
                                record.getIncome(),
                                record.getAtv(),
                                record.getSumAtv(),
                                iedz,soc_apd,netto);//null pointer exception
                                     }
            else
            {
                System.out.println("Kļūda alga ievadīta zem 0");
                input.nextLine();
            }           
            }
            catch ( FormatterClosedException formatterClosedException ){
                System.err.println("Kļūda rakstot failā");
                return;
            }
            catch (NoSuchElementException elementException){
                System.err.println("Nepareizs ievads. Mēģiniet vēlreiz");
                input.nextLine();
            }
        //  System.out.printf("%s  \n", "Ievadiet mēneša ienākumus ");
            ca.add(Calendar.MONTH, 1);
                i++;

        }

Thanks :)

Upvotes: 0

Views: 67

Answers (1)

JB Nizet
JB Nizet

Reputation: 691715

Calendar ca = Calendar.getInstance(); // this is NOW

// set the date to the first of the month, to avoid surprises if the current date is 31.
ca.set(Calendar.DAY_OF_MONTH, 1);

// go n months before the first of this month
ca.add(Calendar.MONTH, -n);

for (int i = 0; i < n; i++) {
    // todo: format the date as you want and print it. See SimpleDateFormat

    // go to the next month
    ca.add(Calendar.MONTH, 1);
}

Upvotes: 2

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