커플링을 이용한 자연수 구현, 소수 구현, 명령형 프로그래밍

ClassifierAlpha.java

package functional.stage2;

import java.util.Iterator;

/**
 * 커플링을 이용한 자연수 분류기 
 * 
 * @author whitebeard-k
 *
 */
public class ClassifierAlpha extends FactorsBeta {

	public ClassifierAlpha(int number) {
		super(number);
	}

	public int sum() {
		Iterator<Integer> it = factors().iterator();
		int sum = 0;
		while (it.hasNext())
			sum += (Integer) it.next();
		return sum;
	}

	public boolean isPerfect() {
		return sum() - number == number;
	}

	public boolean isAbundant() {
		return sum() - number > number;
	}

	public boolean isDeficient() {
		return sum() - number < number;
	}
}

FactorsBeta.java

package functional.stage2;

import java.util.HashSet;
import java.util.Set;

/**
 * 커플링 슈퍼 클래스 
 * 
 * @author whitebeard-k
 *
 */
public class FactorsBeta {

	protected int number;

	public FactorsBeta(int number) {
		this.number = number;
	}

	public boolean isFactor(int potential_factor) {
		return number % potential_factor == 0;
	}

	public Set<Integer> factors() {
		HashSet<Integer> factors = new HashSet<>();
		for (int i = 1; i <= Math.sqrt(number); i++)
			if (isFactor(i)) {
				factors.add(i);
				factors.add(number / i);
			}

		return factors;
	}

}

PrimeAlpha.java

package functional.stage2;

import java.util.HashSet;
import java.util.Set;

/**
 * 커플링을 이용한 소수 구현 
 * 
 * @author whitebeard-k
 *
 */
public class PrimeAlpha extends FactorsBeta {
    
    public PrimeAlpha(int number) {
        super(number);
    }

    public boolean isPrime() {
        Set<Integer> primeSet = new HashSet<Integer>() {
            private static final long serialVersionUID = -8476421042584796116L;

            {
                add(1);
                add(number);
            }
        };
        return factors().equals(primeSet);
    }

}