--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/fschmidt/util/java/ClassUtils.java	Sun Oct 05 17:24:15 2025 -0600
@@ -0,0 +1,65 @@
+package fschmidt.util.java;
+
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.WeakHashMap;
+
+
+public final class ClassUtils {
+
+	private ClassUtils() {}  // never
+
+	private static final class Key {
+		private final String name;
+		private final Class[] parameterTypes;
+
+		private Key(Method m) {
+			this(m.getName(),m.getParameterTypes());
+		}
+
+		private Key(String name,Class[] parameterTypes) {
+			this.name = name;
+			this.parameterTypes = parameterTypes;
+		}
+
+		public boolean equals(Object obj) {
+			if( !(obj instanceof Key) )
+				return false;
+			Key key = (Key)obj;
+			return key.name.equals(name) && Arrays.equals(key.parameterTypes,parameterTypes);
+		}
+
+		public int hashCode() {
+			return name.hashCode()+31*Arrays.hashCode(parameterTypes);
+		}
+	}
+
+	private static final Map<Class,FutureValue<Map<Key,Method>>> cache = new WeakHashMap<Class,FutureValue<Map<Key,Method>>>();
+
+	// return null if not found
+	public static Method getMethod(final Class cls,String name,Class... parameterTypes) {
+		FutureValue<Map<Key,Method>> ft;
+		synchronized(cache) {
+			ft = cache.get(cls);
+			if( ft==null ) {
+				ft = new FutureValue<Map<Key,Method>>() {
+					protected Map<Key,Method> compute() {
+						Map<Key,Method> map = new HashMap<Key,Method>();
+						for( Method m : cls.getMethods() ) {
+							Method m2 = map.put(new Key(m),m);
+							if( m2 != null )
+								throw new RuntimeException("duplicate methods "+m+" and "+m2);
+						}
+						return map;
+					}
+				};
+				cache.put(cls,ft);
+			}
+		}
+		Key key = new Key(name,parameterTypes);
+		return ft.get().get(key);
+	}
+
+}