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comparison src/fschmidt/util/java/ClassUtils.java @ 68:00520880ad02

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add fschmidt source
author Franklin Schmidt <fschmidt@gmail.com>
date Sun, 05 Oct 2025 17:24:15 -0600
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67:9d0fefce6985 68:00520880ad02
1 package fschmidt.util.java;
2
3 import java.lang.reflect.Method;
4 import java.util.Arrays;
5 import java.util.HashMap;
6 import java.util.Map;
7 import java.util.WeakHashMap;
8
9
10 public final class ClassUtils {
11
12 private ClassUtils() {} // never
13
14 private static final class Key {
15 private final String name;
16 private final Class[] parameterTypes;
17
18 private Key(Method m) {
19 this(m.getName(),m.getParameterTypes());
20 }
21
22 private Key(String name,Class[] parameterTypes) {
23 this.name = name;
24 this.parameterTypes = parameterTypes;
25 }
26
27 public boolean equals(Object obj) {
28 if( !(obj instanceof Key) )
29 return false;
30 Key key = (Key)obj;
31 return key.name.equals(name) && Arrays.equals(key.parameterTypes,parameterTypes);
32 }
33
34 public int hashCode() {
35 return name.hashCode()+31*Arrays.hashCode(parameterTypes);
36 }
37 }
38
39 private static final Map<Class,FutureValue<Map<Key,Method>>> cache = new WeakHashMap<Class,FutureValue<Map<Key,Method>>>();
40
41 // return null if not found
42 public static Method getMethod(final Class cls,String name,Class... parameterTypes) {
43 FutureValue<Map<Key,Method>> ft;
44 synchronized(cache) {
45 ft = cache.get(cls);
46 if( ft==null ) {
47 ft = new FutureValue<Map<Key,Method>>() {
48 protected Map<Key,Method> compute() {
49 Map<Key,Method> map = new HashMap<Key,Method>();
50 for( Method m : cls.getMethods() ) {
51 Method m2 = map.put(new Key(m),m);
52 if( m2 != null )
53 throw new RuntimeException("duplicate methods "+m+" and "+m2);
54 }
55 return map;
56 }
57 };
58 cache.put(cls,ft);
59 }
60 }
61 Key key = new Key(name,parameterTypes);
62 return ft.get().get(key);
63 }
64
65 }