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How to define a shared member variable in an enumeration?

I want to reference the enum method to retrieve an algorithm class so that I can lazily load a new instance of the algorithm for use in the strategy design template.

In this example, I use enumeration to refer to three different classes of strategies that calculate the Fibonacci numbers: RecursiveFibonacciGenerator, IterativeFibonacciGeneratorand MemoizedFibonacciGenerator(all of which are inherited from FibonacciGenerator).

The code (with lines generating errors commented out with intent) is as follows:

package com.example.strategy;

public class Fibonacci {
    private enum Algorithm {
        RECURSIVE (RecursiveFibonacciGenerator.class),
        ITERATIVE (IterativeFibonacciGenerator.class),
        MEMOIZED (MemoizedFibonacciGenerator.class);

        private final Class<T> algorithmClass; // Declare class of same type as constructor
        private final T instance; // Declare instance of class defined in constructor
        private <T extends FibonacciGenerator> Algorithm(Class<T> algorithmClass) {
            this.algorithmClass = algorithmClass;
        }

        public T getInstance() {
            if (this.instance == null) {
                this.instance = this.algorithmClass.newInstance();
            }
            return this.instance;
        }
    }

    public Integer getTerm(Integer termNumber) {
        profileGenerator(termNumber, Algorithm.RECURSIVE);
        profileGenerator(termNumber, Algorithm.ITERATIVE);
        return profileGenerator(termNumber, Algorithm.MEMOIZED);
    }

    private Integer profileGenerator(Integer termNumber, Algorithm algorithm) {
        System.out.print("Computing term using " + algorithm.toString() + " algorithm... ");
        Long startTimeMilliseconds = System.currentTimeMillis();
        Integer term = algorithm.getInstance().generateTerm(termNumber);
        Long endTimeMilliseconds = System.currentTimeMillis();
        Long computationTimeMilliseconds = endTimeMilliseconds - startTimeMilliseconds;
        System.out.println("term computed in " + computationTimeMilliseconds + " milliseconds");
    }
}

I would like to know how I can use this constructor enumto store a member variable of a type Class<T>.

Edit: Added full code to clarify intent

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source share
5
public enum Algorithm {
    RECURSIVE(FibonacciGenerator.RecursiveFibonacciGenerator.class),
    ITERATIVE(FibonacciGenerator.IterativeFibonacciGenerator.class),
    MEMOIZED(FibonacciGenerator.MemoizedFibonacciGenerator.class);

    private final Class<? extends FibonacciGenerator> algorithmClass;

    private <T extends FibonacciGenerator> Algorithm(Class<T> algorithmClass) {
        this.algorithmClass = algorithmClass;
    }
}

, ?

- , , , . , ?

+4

:

public enum Algorithm {
    RECURSIVE (new RecursiveFibonacciGenerator()),
    ITERATIVE (new IterativeFibonacciGenerator()),
    MEMOIZED (new MemoizedFibonacciGenerator());

    private <T extends FibonacciGenerator> Algorithm(T algorithm) {}
}
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. - , , :

private final FibonacciGenerator _instance;

private Algorithm(FibonacciGenerator instance) {
    _instance = instance;
}

getFibonacciGenerator(). , generics, , . ""

+1

, , -:

public enum Algorithm {
  RECURSIVE (RecursiveFibonacciGenerator.class),
  ITERATIVE (IterativeFibonacciGenerator.class),
  MEMOIZED (MemoizedFibonacciGenerator.class);

  private Class<? extends FibonacciGenerator> strategy;

  private Algorithm(Class<? extends FibonacciGenerator> algorithmClass) {
    this.strategy = algorithmClass;
  }

  Class<? extends FibonacciGenerator> getStrategy() {
    return strategy;
  }
}
0

:

package com.example.strategy;

public class Fibonacci {
    private enum Algorithm {
        UNDEFINED (null),
        RECURSIVE (RecursiveFibonacciGenerator.class),
        ITERATIVE (IterativeFibonacciGenerator.class),
        MEMOIZED (MemoizedFibonacciGenerator.class);

        private final Class<? extends FibonacciGenerator> algorithmClass;
        private FibonacciGenerator instance;
        private <T extends FibonacciGenerator> Algorithm(Class<T> algorithmClass) {
            this.algorithmClass = algorithmClass;
        }

        public FibonacciGenerator getInstance() {
            if (this.instance == null) {
                try {
                    this.instance = this.algorithmClass.newInstance();
                } catch (InstantiationException e) {
                    e.printStackTrace();
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                }
            }
            return this.instance;
        }
    }

    public Integer getTerm(Integer termNumber) {
        return profileGenerator(termNumber, Algorithm.MEMOIZED);
    }

    private Integer profileGenerator(Integer termNumber, Algorithm algorithm) {
        System.out.print("Computing term using " + algorithm.toString() + " algorithm... ");
        Long startTimeMilliseconds = System.currentTimeMillis();
        Integer term = algorithm.getInstance().generateTerm(termNumber);
        Long endTimeMilliseconds = System.currentTimeMillis();
        Long computationTimeMilliseconds = endTimeMilliseconds - startTimeMilliseconds;
        System.out.println("term computed in " + computationTimeMilliseconds + " milliseconds");
        return term;
    }
}
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