java - Object to list -> why do I have to create a new object? -

i understand why following happens:

datatype bank

public class bank {     string blz; string name;      public string getblz() {         return blz;     }     public void setblz(string blz) {         this.blz = blz;     }     public string getname() {         return name;     }     public void setname(string name) {         this.name = name;     }     } 

this works expected:

public list<bank> getsearchresult() {                 list<bank> banks = new arraylist<>();         bank bank = new bank();         bank.setblz("1");         bank.setname("berlin");         banks.add(bank);         bank = new bank();         bank.setblz("8");         bank.setname("münchen");         banks.add(bank);         return banks;     } 

the list hast first element 1 / berlin , second 8 / münchen. don't understand:

public list<bank> getsearchresult() {                     list<bank> banks = new arraylist<>();         bank bank = new bank();         bank.setblz("1");         bank.setname("berlin");         banks.add(bank);         //bank = new bank();         bank.setblz("8");         bank.setname("münchen");         banks.add(bank);         return banks;     } 

if don't create new object bank shown above, list contains 2 times 8 / münchen. why happen? don't understand this, because when add first element contains 1 / berlin. overwrite values , add second.

thanks

you're modifying existing list. list allows duplication, won't prevent add objects same value twice. prevent duplicates can this:

myhashset = new hashset<bank>(bank); 

and then:

banks = new list<bank>(myhashset); 

set doesn't allow duplication.