Whether double wrapper class supports float argument?

Question

As per Java tutorials, Double Wrapper class supports String and Double as argument.

But I am able to use float argument. Check below code. Can some clarify this?

class test {

public static void main(String[] args)
{

    Double d=new Double(10.5f);

    Double d1=new Double("10.5f");

    System.out.println(d);  
    System.out.println(d1);

}   

}

Output:

10.5 10.5

Answer 1

Java automatically promotes float to double if needed (it's called a widening conversion).

See the JLS for details