diff --git a/java/src/main/java/io/nayuki/qrcodegen/QrCode.java b/java/src/main/java/io/nayuki/qrcodegen/QrCode.java
index 7013ed7..67d49f0 100644
--- a/java/src/main/java/io/nayuki/qrcodegen/QrCode.java
+++ b/java/src/main/java/io/nayuki/qrcodegen/QrCode.java
@@ -204,8 +204,6 @@ public final class QrCode {
 		return new QrCode(version, ecl, dataCodewords, mask);
 	}
 	
-	
-	
 	/*---- Instance fields ----*/
 	
 	// Public immutable scalar parameters:
diff --git a/java/src/main/java/io/nayuki/qrcodegen/QrSegmentAdvanced.java b/java/src/main/java/io/nayuki/qrcodegen/QrSegmentAdvanced.java
index 1efe7b5..6480897 100644
--- a/java/src/main/java/io/nayuki/qrcodegen/QrSegmentAdvanced.java
+++ b/java/src/main/java/io/nayuki/qrcodegen/QrSegmentAdvanced.java
@@ -64,14 +64,14 @@ public final class QrSegmentAdvanced {
 		// Check arguments
 		Objects.requireNonNull(text);
 		Objects.requireNonNull(ecl);
-		if (!(QrCode.MIN_VERSION <= minVersion && minVersion <= maxVersion && maxVersion <= QrCode.MAX_VERSION))
+		if (not_Valid_Version(minVersion, maxVersion))
 			throw new IllegalArgumentException("Invalid value");
 		
 		// Iterate through version numbers, and make tentative segments
 		List<QrSegment> segs = null;
 		int[] codePoints = toCodePoints(text);
 		for (int version = minVersion; ; version++) {
-			if (version == minVersion || version == 10 || version == 27)
+			if (is_valid_version(minVersion, version))
 				segs = makeSegmentsOptimally(codePoints, version);
 			assert segs != null;
 			
@@ -88,6 +88,16 @@ public final class QrSegmentAdvanced {
 			}
 		}
 	}
+
+
+	private static boolean is_valid_version(int minVersion, int version) {
+		return version == minVersion || version == 10 || version == 27;
+	}
+
+
+	private static boolean not_Valid_Version(int minVersion, int maxVersion) {
+		return !(QrCode.MIN_VERSION <= minVersion && minVersion <= maxVersion && maxVersion <= QrCode.MAX_VERSION);
+	}
 	
 	
 	// Returns a new list of segments that is optimal for the given text at the given version number.
@@ -123,22 +133,22 @@ public final class QrSegmentAdvanced {
 		
 		// Calculate costs using dynamic programming
 		for (int i = 0; i < codePoints.length; i++) {
-			int c = codePoints[i];
+			int cPoint = codePoints[i];
 			int[] curCosts = new int[numModes];
 			{  // Always extend a byte mode segment
-				curCosts[0] = prevCosts[0] + countUtf8Bytes(c) * 8 * 6;
+				curCosts[0] = prevCosts[0] + countUtf8Bytes(cPoint) * 8 * 6;
 				charModes[i][0] = modeTypes[0];
 			}
 			// Extend a segment if possible
-			if (QrSegment.ALPHANUMERIC_CHARSET.indexOf(c) != -1) {  // Is alphanumeric
+			if (is_alphanumeric(cPoint)) {  // Is alphanumeric
 				curCosts[1] = prevCosts[1] + 33;  // 5.5 bits per alphanumeric char
 				charModes[i][1] = modeTypes[1];
 			}
-			if ('0' <= c && c <= '9') {  // Is numeric
+			if (is_numeric(cPoint)) {  // Is numeric
 				curCosts[2] = prevCosts[2] + 20;  // 3.33 bits per digit
 				charModes[i][2] = modeTypes[2];
 			}
-			if (isKanji(c)) {
+			if (isKanji(cPoint)) {
 				curCosts[3] = prevCosts[3] + 78;  // 13 bits per Shift JIS char
 				charModes[i][3] = modeTypes[3];
 			}
@@ -147,7 +157,8 @@ public final class QrSegmentAdvanced {
 			for (int j = 0; j < numModes; j++) {  // To mode
 				for (int k = 0; k < numModes; k++) {  // From mode
 					int newCost = (curCosts[k] + 5) / 6 * 6 + headCosts[j];
-					if (charModes[i][k] != null && (charModes[i][j] == null || newCost < curCosts[j])) {
+					boolean is_notNull_or_lower = charModes[i][k] != null && (charModes[i][j] == null || newCost < curCosts[j]);
+					if (is_notNull_or_lower) {
 						curCosts[j] = newCost;
 						charModes[i][j] = modeTypes[k];
 					}
@@ -179,6 +190,16 @@ public final class QrSegmentAdvanced {
 		}
 		return result;
 	}
+
+
+	private static boolean is_numeric(int c) {
+		return '0' <= c && c <= '9';
+	}
+
+
+	private static boolean is_alphanumeric(int c) {
+		return QrSegment.ALPHANUMERIC_CHARSET.indexOf(c) != -1;
+	}
 	
 	
 	// Returns a new list of segments based on the given text and modes, such that
@@ -277,8 +298,7 @@ public final class QrSegmentAdvanced {
 	 */
 	public static boolean isEncodableAsKanji(String text) {
 		Objects.requireNonNull(text);
-		return text.chars().allMatch(
-			c -> isKanji((char)c));
+		return text.chars().allMatch(c -> isKanji((char)c));
 	}