Thread: What does this short part of a code do?

  public boolean same_State (Search_State s2) {
    Jugs_State js2= (Jugs_State) s2;
 
    return ((j1==js2.get_j1())&& (j2==js2.get_j2()));
    }

I just want to know what the part :

Jugs_State js2= (Jugs_State) s2;

does.

I know you can create an object by e.g. Classname object = new Classname() but
what is this "(Jugs_State)" in the brackets and why is there no "new" and why is
there a new variable "s2" after that.

Finally, what is the return doing at the end?

Thanks a lot, I just need a general answer of what the code is doing
not exactly what my classes do (that's why I haven't included all the code
it's long).

It looks to be 'type casting' your passed in parameter 's2'

Originally Posted by Kranti1992

  public boolean same_State (Search_State s2) {
    Jugs_State js2= (Jugs_State) s2;
    return ((j1==js2.get_j1())&& (j2==js2.get_j2()));

I just want to know what the part :

Jugs_State js2= (Jugs_State) s2;

does.

Jugs_State is apparently a subclass of Search_State. The data type of the function's parameter is Search_State, but the function apparently requires the Jugs_State methods get_j1() and get_j2() to calculate its return value.

The object s2 already exists so the code in the function declares a reference variable of type Jugs_State named js2. It can't set js2 equal to s2 directly since they are different data types.

That's why a cast is required. This type of casting is valid since the objects are compatible.

There is no "new" in the declaration of js2 because it is not creating a new object, it is referring to the object that is the function's parameter.

Reference: Java Tutorial: Inheritance


Cheers!

Z