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

  1. #1
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    Default 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).
    Last edited by Kranti1992; July 28th, 2012 at 05:46 AM.


  2. #2
    Junior Member hackthisred's Avatar
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    Default Re: What does this short part of a code do?

    It looks to be 'type casting' your passed in parameter 's2'
    f34r th3 kut3 1z

  3. #3
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    Default Re: What does this short part of a code do?

    Quote Originally Posted by Kranti1992 View Post
      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
    Last edited by Zaphod_b; July 28th, 2012 at 11:09 AM.

  4. #4
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    Default Re: What does this short part of a code do?

    About the return,
    return ((j1==js2.get_j1())&& (j2==js2.get_j2()));
    The function is from type Boolean, so it will either return true or false.
    The && sign is the AND operator. and the == sign is to check if 2 variables are equal to each other.
    j1 and j2 are probably some variables declared somewhere in the code.

    You should be able to draw a conclusion from this. If you are still having trouble finding out what it will return, respond.

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