enum CatColor { BLACK, GREY, ORANGE, CALICO, TORTOISESHELL }
class Cat {
    String name;
    CatColor color;
    double clawSharpness;  // in range [0.0, 1.0], with 1.0 being razor-sharp.
    


    public static void main(String... __) {
        tryMutatePrimitiveVars();
        tryMutateObjectVars();
        }

    static void tryMutatePrimitiveVars() {
        int n = 32;
        System.out.println( "n before: " + n );
        tripleArg(n);
        System.out.println( "n after:  " + n );
        System.out.println( "We note that other methods CANNOT change our local var `n`." );
        System.out.println( "" );
        }

    static int tripleArg( int k ) { 
        System.out.println( "   tripleArg: k=" + k );
        k = 3*k;
        System.out.println( "   tripleArg: k=" + k );
        return k; 
        }
    



    static void tryMutateObjectVars() {
        Cat meowser = new Cat( "Mr Purrscratch", CatColor.ORANGE, 0.8 );

        System.out.println("meowser holds " + meowser.toString() 
                         + " which prints as " + meowser.myToString() );

        System.out.println("Uh-oh, painting the cat black:");
        meowser.setColor(CatColor.BLACK);
        System.out.println("meowser holds " + meowser.toString() 
                         + " which prints as " + meowser.myToString() );
        System.out.println( "Other methods CANNOT change my local var `meowser`, but CAN change the memory that meowser points to." );

        System.out.println("\nNow calling assignToArg:");
        assignToArg(meowser);
        System.out.println("meowser holds " + meowser.toString() 
                         + " which prints as " + meowser.myToString() );
        System.out.println( "Other methods CANNOT change my local var `meowser`." );
        }
            


    static void assignToArg( Cat some_kat ) {
	System.out.println( "   assignToArg: some_kat=" + some_kat.toString()
                          + ", which prints as " + some_kat.myToString() );
        some_kat = new Cat( "Kat", CatColor.TORTOISESHELL, 0.4 );
	System.out.println( "   assignToArg: some_kat=" + some_kat.toString()
                          + ", which prints as " + some_kat.myToString() );
        }

    void setColor( /* Cat this, */ CatColor _color ) {
        this.color = _color;
        }



    public String myToString( /* Cat this */ ) {
        return "new Cat( "
             + "\"" + this.name   + "\", "
             + this.color  + ", "
             + this.clawSharpness + " "
             + ")";
        }


    public Cat( String _name, CatColor _color, double _clawSharpness ) {
        this.name          = _name;
        this.color         = _color;
        this.clawSharpness = _clawSharpness;
        }

    }