Can C# style object initialization be used in Java?

Question

In C# it's possible to write:

MyClass obj = new MyClass()
{
    field1 = "hello",
    field2 = "world",
    field3 = new MyOtherClass()
    {
        etc....
    }
}

I can see that array initialization can be done in a similar way but can something similar to the above be done in Java too, and if so, what's the syntax?

Answer 1

That initialization syntax is not present in Java.

A similar approach is to use double brace initialization, where you create an anonymous inner sub class with an initializer block:

MyClass obj = new MyClass() {{
  // in Java these would be more like this: setFieldX(value);
  field1 = "hello";
  field2 = "world";
  field3 = new MyOtherClass() ...
}};

Be aware though, that you're actually creating a subclass.

Another approach is to create a builder for MyClass, and have code like this:

MyClass obj = new MyClassBuilder().
  withField1("hello").
  withField2("world").
  withField3(new MyOtherClass()).
  build();