Java example source code file (PrimesTest.java)

This example Java source code file (PrimesTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

alejandro, alpern's, below_2, dario, exception, hashset, list, not_primes, primes, primes_set, primestest, test, throwable, util

The PrimesTest.java Java example source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.math3.primes;


import java.util.HashSet;
import java.util.List;

import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.junit.Assert;
import org.junit.Test;

public class PrimesTest {

    public static final int[] PRIMES = {//primes here have been verified one by one using Dario Alejandro Alpern's tool, see http://www.alpertron.com.ar/ECM.HTM
            2,3,5,7,11,13,17,19,23,29,31,43,47,53,71,73,79,89,97,
            107,137,151,157,271,293,331,409,607,617,683,829,
            1049,1103,1229,1657,
            2039,2053,//around first boundary in miller-rabin
            2251,2389,2473,2699,3271,3389,3449,5653,6449,6869,9067,9091,
            11251,12433,12959,22961,41047,46337,65413,80803,91577,92693,
            118423,656519,795659,
            1373639,1373677,//around second boundary in miller-rabin
            588977,952381,
            1013041,1205999,2814001,
            22605091,
            25325981,25326023,//around third boundary in miller-rabin
            100000007,715827881,
            2147483647//Integer.MAX_VALUE
            };

    public static final int[] NOT_PRIMES = {//composite chosen at random + particular values used in algorithms such as boundaries for millerRabin
            4,6,8,9,10,12,14,15,16,18,20,21,22,24,25,
            275,
            2037,2041,2045,2046,2047,2048,2049,2051,2055,//around first boundary in miller-rabin
            9095,
            463465,
            1373637,1373641,1373651,1373652,1373653,1373654,1373655,1373673,1373675,1373679,//around second boundary in miller-rabin
            25325979,25325983,25325993,25325997,25325999,25326001,25326003,25326007,25326009,25326011,25326021,25326025,//around third boundary in miller-rabin
            100000005,
            1073741341,1073741823,2147473649,2147483641,2147483643,2147483645,2147483646};

    public static final int[] BELOW_2 = {
            Integer.MIN_VALUE,-1,0,1};

    void assertPrimeFactorsException(int n, Throwable expected) {
        try {
            Primes.primeFactors(n);
            Assert.fail("Exception not thrown");
        } catch (Throwable e) {
            Assert.assertEquals(expected.getClass(), e.getClass());
            if (expected.getMessage() != null) {
                Assert.assertEquals(expected.getMessage(), e.getMessage());
            }
        }
    }
    void assertNextPrimeException(int n, Throwable expected){
        try {
            Primes.nextPrime(n);
            Assert.fail("Exception not thrown");
        } catch(Throwable e) {
            Assert.assertEquals(expected.getClass(), e.getClass());
            if (expected.getMessage() != null) {
                Assert.assertEquals(expected.getMessage(), e.getMessage());
            }
        }
    }

    @Test
    public void testNextPrime() {

        Assert.assertEquals(2, Primes.nextPrime(0));
        Assert.assertEquals(2, Primes.nextPrime(1));
        Assert.assertEquals(2, Primes.nextPrime(2));
        Assert.assertEquals(3, Primes.nextPrime(3));
        Assert.assertEquals(5, Primes.nextPrime(4));
        Assert.assertEquals(5, Primes.nextPrime(5));

        for (int i = 0; i < SmallPrimes.PRIMES.length - 1; i++) {
            for (int j = SmallPrimes.PRIMES[i] + 1; j <= SmallPrimes.PRIMES[i + 1]; j++) {
                Assert.assertEquals(SmallPrimes.PRIMES[i+1], Primes.nextPrime(j));
            }
        }

        Assert.assertEquals(25325981, Primes.nextPrime(25325981));
        for (int i = 25325981 + 1; i <= 25326023; i++) {
            Assert.assertEquals(25326023, Primes.nextPrime(i));
        }

        Assert.assertEquals(Integer.MAX_VALUE, Primes.nextPrime(Integer.MAX_VALUE - 10));
        Assert.assertEquals(Integer.MAX_VALUE, Primes.nextPrime(Integer.MAX_VALUE - 1));
        Assert.assertEquals(Integer.MAX_VALUE, Primes.nextPrime(Integer.MAX_VALUE));

        assertNextPrimeException(Integer.MIN_VALUE, new MathIllegalArgumentException(LocalizedFormats.NUMBER_TOO_SMALL,Integer.MIN_VALUE,0));
        assertNextPrimeException(-1, new MathIllegalArgumentException(LocalizedFormats.NUMBER_TOO_SMALL,-1,0));
        assertNextPrimeException(-13, new MathIllegalArgumentException(LocalizedFormats.NUMBER_TOO_SMALL,-13,0));
    }

    @Test
    public void testIsPrime() throws Exception {
        for (int i : BELOW_2) {
            Assert.assertFalse(Primes.isPrime(i));
        }
        for (int i:NOT_PRIMES) {
            Assert.assertFalse(Primes.isPrime(i));
        }
        for (int i:PRIMES) {
            Assert.assertTrue(Primes.isPrime(i));
        }
    }

    static int sum(List<Integer> numbers){
        int out = 0;
        for (int i:numbers) {
            out += i;
        }
        return out;
    }
    static int product(List<Integer> numbers) {
        int out = 1;
        for (int i : numbers) {
            out *= i;
        }
        return out;
    }
    static final HashSet<Integer> PRIMES_SET = new HashSet();
    static {
        for (int p : PRIMES) {
            PRIMES_SET.add(p);
        }
    }
    static void checkPrimeFactors(List<Integer> factors){
        for (int p : factors) {
            if (!PRIMES_SET.contains(p)) {
                Assert.fail("Not found in primes list: " + p);
            }
        }
    }

    @Test
    public void testPrimeFactors() throws Exception {
        for (int i : BELOW_2) {
            assertPrimeFactorsException(i, new MathIllegalArgumentException(LocalizedFormats.NUMBER_TOO_SMALL,i,2));
        }
        for (int i : NOT_PRIMES) {
            List<Integer> factors = Primes.primeFactors(i);
            checkPrimeFactors(factors);
            int prod = product(factors);
            Assert.assertEquals(i, prod);
        }
        for (int i : PRIMES) {
            List<Integer> factors = Primes.primeFactors(i);
            Assert.assertEquals(i, (int)factors.get(0));
            Assert.assertEquals(1, factors.size());
        }
    }
}