Generating a new instance of a List in C# -

i have problem using c#, if initialize list, lets list<t> examplelist using pre-existing list, lets tomodify this: list<t> examplelist = new list<t>(tomodify). when later modify tomodify list newly created list modifies itself. if passes value reference shouldn't value of examplelist stay same since generated other one?

tldr: value of list initialize using list(second list) changes when change second list. come java background , can't understand why happens. have use clone?

let use example :

        list<a> firstlist = new list<a>()         {             new a() { id = 3 },             new a() { id = 5 }         };          list<a> secondlist = new list<a>(firstlist);          secondlist[1].id = 999;          console.writeline(firstlist[1].id); 

output : 999

the main reason though create new list<t> object (yes collection object well) points new memory allocated in managed heap still works references same objects.

to create list of new (!) objects same values need clone elements somehow, 1 way use linq .select() method create new objects , tolist() method convert list :

        list<a> firstlist = new list<a>()         {             new a() { id = 3 },             new a() { id = 5 }         };          list<a> secondlist = firstlist.select(el => new a() { id = el.id }).tolist();          secondlist[1].id = 999;          console.writeline(firstlist[1].id); 

output : 5