comment on required Java version

Author: TilmanNeumann

src/main/java/de/tilman_neumann/jml/factor/pollardRho/PollardRhoBrentMontgomery64.java

@@ -1,6 +1,6 @@
 /*
  * java-math-library is a Java library focused on number theory, but not necessarily limited to it. It is based on the PSIQS 4.0 factoring project.
- * Copyright (C) 2018-2024 Tilman Neumann - tilman.neumann@web.de
+ * Copyright (C) 2018-2025 Tilman Neumann - tilman.neumann@web.de
  *
  * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.
@@ -46,7 +46,7 @@ public class PollardRhoBrentMontgomery64 extends FactorAlgorithm {
 	private static final Logger LOG = LogManager.getLogger(PollardRhoBrentMontgomery64.class);
 	private static final boolean DEBUG = false;
 
-	private static final Rng RNG = new Rng();
+	private static final Rng RNG = new Rng(); // the numbers produced by java.util.Random.nextLong(bound) have better quality, but that needs Java 17
 
 	// The reducer R is 2^64, but the only constant still required is the half of it.
 	private static final long R_HALF = 1L << 63;

src/main/java/de/tilman_neumann/jml/factor/pollardRho/PollardRhoBrentMontgomery64MH.java

@@ -1,6 +1,6 @@
 /*
  * java-math-library is a Java library focused on number theory, but not necessarily limited to it. It is based on the PSIQS 4.0 factoring project.
- * Copyright (C) 2018-2024 Tilman Neumann - tilman.neumann@web.de
+ * Copyright (C) 2018-2025 Tilman Neumann - tilman.neumann@web.de
  *
  * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.
@@ -50,7 +50,7 @@ public class PollardRhoBrentMontgomery64MH extends FactorAlgorithm {
 	private static final Logger LOG = LogManager.getLogger(PollardRhoBrentMontgomery64MH.class);
 	private static final boolean DEBUG = false;
 
-	private static final Rng RNG = new Rng();
+	private static final Rng RNG = new Rng(); // the numbers produced by java.util.Random.nextLong(bound) have better quality, but that needs Java 17
 
 	// The reducer R is 2^64, but the only constant still required is the half of it.
 	private static final long R_HALF = 1L << 63;

src/main/java/de/tilman_neumann/jml/factor/pollardRho/PollardRhoBrentMontgomery64MHInlined.java

@@ -1,6 +1,6 @@
 /*
  * java-math-library is a Java library focused on number theory, but not necessarily limited to it. It is based on the PSIQS 4.0 factoring project.
- * Copyright (C) 2018-2024 Tilman Neumann - tilman.neumann@web.de
+ * Copyright (C) 2018-2025 Tilman Neumann - tilman.neumann@web.de
  *
  * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.
@@ -50,7 +50,7 @@ public class PollardRhoBrentMontgomery64MHInlined extends FactorAlgorithm {
 	private static final Logger LOG = LogManager.getLogger(PollardRhoBrentMontgomery64MHInlined.class);
 	private static final boolean DEBUG = false;
 
-	private static final Rng RNG = new Rng();
+	private static final Rng RNG = new Rng(); // the numbers produced by java.util.Random.nextLong(bound) have better quality, but that needs Java 17
 
 	// The reducer R is 2^64, but the only constant still required is the half of it.
 	private static final long R_HALF = 1L << 63;

src/main/java/de/tilman_neumann/jml/random/Rng.java

@@ -57,15 +57,15 @@ public Rng(long seed) {
 	 * @return random int in the desired range
 	 */
 	public int nextInt(int minValue, int maxValue) {
-		int diff = maxValue - minValue;
-		if (diff < 1) throw new IllegalArgumentException("maxValue=" + maxValue + " must be bigger than minValue=" + minValue);
-		int rand = nextInt(diff); // 0...(diff-1)
-		return minValue + rand;
+		return minValue + nextInt(maxValue - minValue);
 	}
 
 	/**
 	 * Creates a random long from the uniform distribution U[0, maxValue-1].
 	 * The only requirement is maxValue > 0.
+	 * 
+	 * The numbers produced by java.util.Random.nextLong(bound) have better quality, but that needs Java 17.
+	 * 
 	 * @param maxValue
 	 * @return random long in the desired range
 	 */
@@ -94,10 +94,7 @@ public long nextLong(long maxValue) {
 	 * @return random long in the desired range
 	 */
 	public long nextLong(long minValue, long maxValue) {
-		long diff = maxValue - minValue;
-		if (diff < 1) throw new IllegalArgumentException("maxValue=" + maxValue + " must be bigger than minValue=" + minValue);
-		long rand = nextLong(diff); // 0...(diff-1)
-		return minValue + rand;
+		return minValue + nextLong(maxValue - minValue);
 	}
 
 	/**

src/test/java/de/tilman_neumann/jml/random/RngPerformanceTest.java

@@ -123,12 +123,12 @@ private static void testNextIntWithLowerUpperBound() {
 		/*
 		if (TEST_SLOW) {
 			for (int i=0; i<NCOUNT; i++) {
-				secureRandom.nextInt(LOWER_INT, UPPER_INT); // XXX which Java version is required ?
+				secureRandom.nextInt(LOWER_INT, UPPER_INT); // needs Java 17
 			}
 			LOG.debug("SecureRandom.nextInt(" + LOWER_INT + ", " + UPPER_INT + ") took " + timer.capture() + " ms");
 		}
 		for (int i=0; i<NCOUNT; i++) {
-			random.nextInt(LOWER_INT, UPPER_INT); // XXX which Java version is required ?
+			random.nextInt(LOWER_INT, UPPER_INT); // needs Java 17
 		}
 		LOG.debug("Random.nextInt(" + LOWER_INT + ", " + UPPER_INT + ") took " + timer.capture() + " ms");
 		*/