fixes GitHub Issue 462 (Internal class issues in the Java 21)

1 files changed, 6 insertions, 3 deletions

diff --git a/src/main/javassist/bytecode/MethodParametersAttribute.java b/src/main/javassist/bytecode/MethodParametersAttribute.java
index b9c252a9..f78f6c72 100644
--- a/src/main/javassist/bytecode/MethodParametersAttribute.java
+++ b/src/main/javassist/bytecode/MethodParametersAttribute.java
@@ -32,7 +32,8 @@ public class MethodParametersAttribute extends AttributeInfo {
         byte[] data = new byte[names.length * 4 + 1];
         data[0] = (byte)names.length;
         for (int i = 0; i < names.length; i++) {
-            ByteArray.write16bit(cp.addUtf8Info(names[i]), data, i * 4 + 1);
+            String name = names[i];
+            ByteArray.write16bit(name == null ? 0 : cp.addUtf8Info(name), data, i * 4 + 1);
             ByteArray.write16bit(flags[i], data, i * 4 + 3);
         }
 
@@ -61,7 +62,8 @@ public class MethodParametersAttribute extends AttributeInfo {
      * @param i         the position of the parameter.
      */
     public String parameterName(int i) {
-        return getConstPool().getUtf8Info(name(i));
+        int index = name(i);
+        return index == 0 ? null : getConstPool().getUtf8Info(index);
     }
 
     /**
@@ -87,7 +89,8 @@ public class MethodParametersAttribute extends AttributeInfo {
         String[] names = new String[s];
         int[] flags = new int[s];
         for (int i = 0; i < s; i++) {
-            names[i] = cp.getUtf8Info(name(i));
+            int index = name(i);
+            names[i] = index == 0 ? null : cp.getUtf8Info(index);
             flags[i] = accessFlags(i);
         }