Question

Based on the post Calculating difference in days between dates

How do I feed the vectors vE and vS with random dates and then return the difference between your dates? Recalling that vS must be greater than vE? Actually, I should separate into two methods: a randomized dates and other calculates the difference.

/*
 * Randomizacao
 */
package random04DiferencaDataVetor;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;

public class Random04DiferencaDataVetor {

    public static void main(String[] args) throws ParseException {


        final long intervalo = 1000000000;
        Random rnd = new Random();
        String[] vE = new String[5];
        String[] vS = new String[5];
        for (int i = 0; i < vE.length; i++) {
            /*
             * arrumar vetores para gerar datas aleatorias
             * lembrando que vS deve ser maior que vE
             */
            retornaData();
        }
    }

    static void retornaData() throws ParseException {
        final long intervalo = 1000000000;
        Random rnd = new Random();
        // formatando as datas
        DateFormat formato = new SimpleDateFormat("yyyy");
        Date anoE = formato.parse("2012");
        long timeE = anoE.getTime();
        Date anoS = formato.parse("2013");
        long timeS = anoS.getTime();
        // define o intervalo de datas em 1 ano
        long tempoIntervalo = timeE - timeS;
        // randomiza a data de entrada
        long rndTempoE = timeE + (long) (rnd.nextDouble() * tempoIntervalo);
        // data entrada
        String dataE = new SimpleDateFormat("hh:mm dd/MM/yyyy").format(rndTempoE);
        // randomiza a data de saida
        long rndTempoS = rndTempoE + (long) (rnd.nextDouble() * intervalo * 2);
        // data de saida
        String dataS = new SimpleDateFormat("hh:mm dd/MM/yyyy").format(rndTempoS);
        // formato de data
        SimpleDateFormat sdf = new SimpleDateFormat("hh:mm dd/MM/yyyy");
        try {
            Date dataEnt = sdf.parse(dataE);
            Date dataSaida = sdf.parse(dataS);
            long differenceMilliSeconds = dataSaida.getTime() - dataEnt.getTime();
            long days = differenceMilliSeconds / 1000 / 60 / 60 / 24;
            long hours = (differenceMilliSeconds % (1000 * 60 * 60 * 24)) / 1000 / 60 / 60;
            long minutes = (differenceMilliSeconds % (1000 * 60 * 60)) / 1000 / 60;
            System.out.println(days + " days, " + hours + " hours, " + minutes + " minutes.");
        } catch (ParseException e) {
            e.printStackTrace();
        }
    }
}

Answer 1

1. You have declared Array not the Vector. You may use `Vector declaration as below:

    Vector<String> vE = new Vector<String>();
    Vector<String> vS = new Vector<String>();
   

   But you may want to use List/ArrayList in place of Vector as below:

    List<String> vE = new ArrayList<String>();
    List<String> vS = new ArrayList<String>();
   

2. To add the date strings in the vectors, you can use add method as below:

    String dateString1 = "01/01/2012";
    vE.add(dateString1);
   

3. To add 5 dates your Vector vE, you may do as below:

    for (int i = 0; i < 5; i++) {
       int day = 1+ rnd.nextInt(28); //day from 1 to 28
       int month = 1+rnd.nextInt(12); //day from 1 to 12
       int year = 2000 +rnd.nextInt(13); //year from 2000 to 2012
       String dateString = month+"/"+day+"/"year;
       vE.add(dateString);
    }
   

4. You may want to pass Vector vE in your retornaData(); method to compute the differences:

        //call in `main` method  outside the `for` loop as:
        retornaData(vE);
   
        //change method signature as 
        static void retornaData(Vector<String> vE) throws ParseException {
   

5. Inside retornaData(), you may want to retrieve two date string and compute the difference:

       String date1 = vE.get(0);//use some index
       String date2 = vE.get(1); //use some index
   
        //compute the difference between date1 and date2
   

If you could use English in your sample program, I may try advising further corrections/improvements.