명령형, 자연수 분류기 , 소수 분류기

ClassifierAlpha.java

package functional.stage1;

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

/**
 * 명령형 자연수 분류기
 * 
 * @author whitebeard-k
 *
 */
public class ClassifierAlpha {
	private int number;

	public ClassifierAlpha(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;
	}

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

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

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

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

PrimeAlpha.java

package functional.stage1;

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

/**
 * 명령형 소수 찾기
 * 
 * @author whitebeard-k
 *
 */
public class PrimeAlpha {
	private int number;

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

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

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

	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;
	}
}