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Thread: Generics

  1. #1
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    Default Generics

    I'm having trouble figuring out how to properly define Generics. Could you let me know what I'm doing wrong here?

    public class MyClass1<T>
    {
      private final MyClass2<T> myobject;
      private final T startValue;
     
      public MyClass1(T value, MyClass2<T> obj)
      {
        startValue = value;
        myobject = obj;
      }
      public void run()
      {
        for ( T i = startValue; i < startValue+3; i++ )
          myobject.run(i);
      }
    }

    Then I call it with this:
    MyClass1<int>  myclass1i = new MyClass1<int> ( 1 , myObj);
    MyClass1<char> myclass1c = new MyClass1<char>('a', myObj);

    I'm sure there are some syntax mistakes, but there is also the problem that i++ isn't recognized. This would be easy in C++ as I'd just have to ensure that any classes which act as the template type need to have ++ overloaded (int and char do support these). I'd only get a compiler error if I used an object which doesn't support this. I'm not sure that it's this easy in Java.


  2. #2
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    Default Re: Generics

    Primitives (int, char, double, etc.) can't replace generic class variables. Use the wrapper classes if you must.

  3. #3
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    Default Re: Generics

    That is certainly too bad. Thanks for the response.

  4. #4
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    Default Re: Generics

    Don't be discouraged. The wrapper classes, Integer, Double, Character, etc. should allow you to do what you need. Or, perhaps you don't need generics at all. Maybe you can achieve the desired result by simply overloading some methods and/or constructors.

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