java GregorianDates

Hello I defined this fuction in class Ergazomenos
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public String toString() {
return "First name is: " + this.onoma +
" Last name is: " + this.epitheto +
"Iperoria is " +this.Iperoria + //1, 1970 00:00:00.000 GMT
"Imerominia proslipsis is " +this.getImerominiaProslipsis()+
"Imeromonia gensis is " +this.getImerominiaGennisis()+
"Afm is"+this.afm +
// "Imerominia apolisis is" +this.imerominiaApolisis.+
"Vassikos misthos is" +this.vasikosMisthos +
"Minaies apodoxes ergazoemon einai " +this.minaiesApodoxes()+
"Taxes ergazomenou einai "+this.tax();

in main I use gregorian calendar like this:
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gnk1[0]= new GenikosDieuthintis("sakis", "mistoxidis", 15000,
100, new GregorianCalendar(1100,02,06),new GregorianCalendar(1100,02,06), 441,
new GregorianCalendar(1100,02,06), 1000, "takis",
new GregorianCalendar(1100,02,06), new GregorianCalendar(1100,02,06),
100, 44, 44,
40);

but the dates are wrong when I run the program.
What should I do?