Fixed out-of-bounds array read in fast Java implementation.

Readme.markdown

@@ -69,7 +69,7 @@ for (int y = 0; y < qr1.size; y++) {
 License
 -------
 
-Copyright © 2025 Project Nayuki. (MIT License)  
+Copyright © 2026 Project Nayuki. (MIT License)  
 [https://www.nayuki.io/page/qr-code-generator-library](https://www.nayuki.io/page/qr-code-generator-library)
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of

java-fast/io/nayuki/fastqrcodegen/QrSegmentAdvanced.java

@@ -130,7 +130,7 @@ public final class QrSegmentAdvanced {
 				charModes[i][0] = modeTypes[0];
 			}
 			// Extend a segment if possible
-			if (QrSegment.ALPHANUMERIC_MAP[c] != -1) {  // Is alphanumeric
+			if (c < QrSegment.ALPHANUMERIC_MAP.length && QrSegment.ALPHANUMERIC_MAP[c] != -1) {  // Is alphanumeric
 				curCosts[1] = prevCosts[1] + 33;  // 5.5 bits per alphanumeric char
 				charModes[i][1] = modeTypes[1];
 			}