CODEWITHSUNDEEP
javaanonymous-types
Ivan
Ivan

Reputation: 10372

Is there a functionality in Java similar to C#'s anonymous types?

I was wondering if there exists a similar functionality in Java similar to C#'s anonymous types:

var a = new {Count = 5, Message = "A string."};

Or does this concept go against the Java paradigm?

EDIT:

I suppose using Hashable() in Java is somewhat similar.

Upvotes: 18

Views: 8856

Answers (4)

koppor
koppor

Reputation: 20531

Yes! With Java 10's var feature:

var o = new Object(){
    int count = 5;
    String message = "A string.";
};
System.out.println(o.count);

More readings:

Upvotes: 0

David DeMar
David DeMar

Reputation: 2670

Java has a feature called local classes, which are somewhat similar. They're useful for creating a class or implementing an interface that doesn't really need to be known about outside of a particular method. The scope of the local class is limited by the code block that defines it.

public void doSomething() {
    class SomeLocalClass {
        public int count = 5;
        public String message = "A string.";
    }

    SomeLocalClass local = new SomeLocalClass();
    System.out.println(local.count);
    System.out.println(local.message);
}

Unlike anonymous types in C#, Java local classes and their fields have explicitly defined types, but I imagine they might have some overlapping use cases.

Upvotes: 4

zacheusz
zacheusz

Reputation: 8842

Maybe you mean sth like this:

Object o = new Object(){
    int count = 5;
    String message = "A string.";
};

@Commenters: of course this is a theoretical, very inconvenient example.

Probably OP may use Map:

Map<String,Object> a = new HashMap<String,Object>();
a.put("Count", 5);
a.put("Message", "A string.");

int count = (Integer)a.get("Count"); //better use Integer instead of int to avoid NPE
String message = (String)a.get("Message");

Upvotes: 11

Mike Samuel
Mike Samuel

Reputation: 120526

No. There is no equivalent. There is no typeless variable declaration (var) in Java that the Java compiler could fill in with the auto-generated type name to allow a.Count and a.Message to be accessed.

Upvotes: 15

Related Questions