1 /*
2 * Copyright (c) 2008, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.invoke;
27
28 import java.lang.constant.ClassDesc;
29 import java.lang.constant.MethodTypeDesc;
30 import java.lang.invoke.MethodHandles.Lookup;
31 import java.lang.module.ModuleDescriptor;
32 import java.lang.ref.WeakReference;
33 import java.lang.reflect.Method;
34 import java.lang.reflect.Modifier;
35 import java.lang.reflect.UndeclaredThrowableException;
36 import java.util.ArrayList;
37 import java.util.Arrays;
38 import java.util.Collections;
39 import java.util.HashSet;
40 import java.util.List;
41 import java.util.Objects;
42 import java.util.Set;
43 import java.util.WeakHashMap;
44 import java.util.concurrent.atomic.AtomicInteger;
45 import java.util.stream.Stream;
46
47 import jdk.internal.access.JavaLangReflectAccess;
48 import jdk.internal.access.SharedSecrets;
49 import java.lang.classfile.ClassHierarchyResolver;
50 import java.lang.classfile.ClassFile;
51 import java.lang.classfile.CodeBuilder;
52 import java.lang.classfile.TypeKind;
53
54 import jdk.internal.constant.ConstantUtils;
55 import jdk.internal.loader.ClassLoaders;
56 import jdk.internal.misc.PreviewFeatures;
57 import jdk.internal.module.Modules;
58 import jdk.internal.util.ClassFileDumper;
59
60 import static java.lang.constant.ConstantDescs.*;
61 import static java.lang.invoke.MethodHandleStatics.*;
62 import static java.lang.invoke.MethodType.methodType;
63 import static java.lang.module.ModuleDescriptor.Modifier.SYNTHETIC;
64 import static java.lang.classfile.ClassFile.*;
65 import static jdk.internal.constant.ConstantUtils.*;
66
67 /**
68 * This class consists exclusively of static methods that help adapt
69 * method handles to other JVM types, such as interfaces.
70 *
71 * @since 1.7
72 */
73 public final class MethodHandleProxies {
74
75 private MethodHandleProxies() { } // do not instantiate
76
77 /**
78 * Produces an instance of the given single-method interface which redirects
79 * its calls to the given method handle.
80 * <p>
81 * A single-method interface is an interface which declares a uniquely named method.
82 * When determining the uniquely named method of a single-method interface,
83 * the public {@code Object} methods ({@code toString}, {@code equals}, {@code hashCode})
84 * are disregarded as are any default (non-abstract) methods.
85 * For example, {@link java.util.Comparator} is a single-method interface,
86 * even though it re-declares the {@code Object.equals} method and also
87 * declares default methods, such as {@code Comparator.reverse}.
88 * <p>
89 * The interface must be public, not {@linkplain Class#isHidden() hidden},
90 * and not {@linkplain Class#isSealed() sealed}.
91 * No additional access checks are performed.
92 * <p>
93 * The resulting instance of the required type will respond to
94 * invocation of the type's uniquely named method by calling
95 * the given target on the incoming arguments,
96 * and returning or throwing whatever the target
97 * returns or throws. The invocation will be as if by
98 * {@code target.invoke}.
99 * The target's type will be checked before the
100 * instance is created, as if by a call to {@code asType},
101 * which may result in a {@code WrongMethodTypeException}.
102 * <p>
103 * The uniquely named method is allowed to be multiply declared,
104 * with distinct type descriptors. (E.g., it can be overloaded,
105 * or can possess bridge methods.) All such declarations are
106 * connected directly to the target method handle.
107 * Argument and return types are adjusted by {@code asType}
108 * for each individual declaration.
109 * <p>
110 * The wrapper instance will implement the requested interface
111 * and its super-types, but no other single-method interfaces.
112 * This means that the instance will not unexpectedly
113 * pass an {@code instanceof} test for any unrequested type.
114 * <p style="font-size:smaller;">
115 * <em>Implementation Note:</em>
116 * Therefore, each instance must implement a unique single-method interface.
117 * Implementations may not bundle together
118 * multiple single-method interfaces onto single implementation classes
119 * in the style of {@link java.desktop/java.awt.AWTEventMulticaster}.
120 * <p>
121 * The method handle may throw an <em>undeclared exception</em>,
122 * which means any checked exception (or other checked throwable)
123 * not declared by the requested type's single abstract method.
124 * If this happens, the throwable will be wrapped in an instance of
125 * {@link java.lang.reflect.UndeclaredThrowableException UndeclaredThrowableException}
126 * and thrown in that wrapped form.
127 * <p>
128 * Like {@link java.lang.Integer#valueOf Integer.valueOf},
129 * {@code asInterfaceInstance} is a factory method whose results are defined
130 * by their behavior.
131 * It is not guaranteed to return a new instance for every call.
132 * <p>
133 * Because of the possibility of {@linkplain java.lang.reflect.Method#isBridge bridge methods}
134 * and other corner cases, the interface may also have several abstract methods
135 * with the same name but having distinct descriptors (types of returns and parameters).
136 * In this case, all the methods are bound in common to the one given target.
137 * The type check and effective {@code asType} conversion is applied to each
138 * method type descriptor, and all abstract methods are bound to the target in common.
139 * Beyond this type check, no further checks are made to determine that the
140 * abstract methods are related in any way.
141 * <p>
142 * Future versions of this API may accept additional types,
143 * such as abstract classes with single abstract methods.
144 * Future versions of this API may also equip wrapper instances
145 * with one or more additional public "marker" interfaces.
146 *
147 * @param <T> the desired type of the wrapper, a single-method interface
148 * @param intfc a class object representing {@code T}
149 * @param target the method handle to invoke from the wrapper
150 * @return a correctly-typed wrapper for the given target
151 * @throws NullPointerException if either argument is null
152 * @throws IllegalArgumentException if the {@code intfc} is not a
153 * valid argument to this method
154 * @throws WrongMethodTypeException if the target cannot
155 * be converted to the type required by the requested interface
156 */
157 @SuppressWarnings("doclint:reference") // cross-module links
158 public static <T> T asInterfaceInstance(final Class<T> intfc, final MethodHandle target) {
159 if (!intfc.isInterface() || !Modifier.isPublic(intfc.getModifiers()))
160 throw newIllegalArgumentException("not a public interface", intfc.getName());
161 if (intfc.isSealed())
162 throw newIllegalArgumentException("a sealed interface", intfc.getName());
163 if (intfc.isHidden())
164 throw newIllegalArgumentException("a hidden interface", intfc.getName());
165 Objects.requireNonNull(target);
166 final MethodHandle mh = target;
167
168 // Define one hidden class for each interface. Create an instance of
169 // the hidden class for a given target method handle which will be
170 // accessed via getfield. Multiple instances may be created for a
171 // hidden class. This approach allows the generated hidden classes
172 // more shareable.
173 //
174 // The implementation class is weakly referenced; a new class is
175 // defined if the last one has been garbage collected.
176 //
177 // An alternative approach is to define one hidden class with the
178 // target method handle as class data and the target method handle
179 // is loaded via ldc/condy. If more than one target method handles
180 // are used, the extra classes will pollute the same type profiles.
181 // In addition, hidden classes without class data is more friendly
182 // for pre-generation (shifting the dynamic class generation from
183 // runtime to an earlier phrase).
184 Class<?> proxyClass = getProxyClass(intfc); // throws IllegalArgumentException
185 Lookup lookup = new Lookup(proxyClass);
186 Object proxy;
187 try {
188 MethodHandle constructor = lookup.findConstructor(proxyClass,
189 MT_void_Lookup_MethodHandle_MethodHandle)
190 .asType(MT_Object_Lookup_MethodHandle_MethodHandle);
191 proxy = constructor.invokeExact(lookup, target, mh);
192 } catch (Throwable ex) {
193 throw uncaughtException(ex);
194 }
195 assert proxy.getClass().getModule().isNamed() : proxy.getClass() + " " + proxy.getClass().getModule();
196 return intfc.cast(proxy);
197 }
198
199 private record MethodInfo(MethodTypeDesc desc, List<ClassDesc> thrown, String fieldName) {}
200
201 private static final ClassFileDumper DUMPER = ClassFileDumper.getInstance(
202 "jdk.invoke.MethodHandleProxies.dumpClassFiles", "DUMP_MH_PROXY_CLASSFILES");
203
204 private static final Set<Class<?>> WRAPPER_TYPES = Collections.newSetFromMap(new WeakHashMap<>());
205 private static final ClassValue<WeakReferenceHolder<Class<?>>> PROXIES = new ClassValue<>() {
206 @Override
207 protected WeakReferenceHolder<Class<?>> computeValue(Class<?> intfc) {
208 return new WeakReferenceHolder<>(newProxyClass(intfc));
209 }
210 };
211
212 private static Class<?> newProxyClass(Class<?> intfc) {
213 List<MethodInfo> methods = new ArrayList<>();
214 Set<Class<?>> referencedTypes = new HashSet<>();
215 referencedTypes.add(intfc);
216 String uniqueName = null;
217 int count = 0;
218 for (Method m : intfc.getMethods()) {
219 if (!Modifier.isAbstract(m.getModifiers()))
220 continue;
221
222 if (isObjectMethod(m))
223 continue;
224
225 // ensure it's SAM interface
226 String methodName = m.getName();
227 if (uniqueName == null) {
228 uniqueName = methodName;
229 } else if (!uniqueName.equals(methodName)) {
230 // too many abstract methods
231 throw newIllegalArgumentException("not a single-method interface", intfc.getName());
232 }
233
234 // the field name holding the method handle for this method
235 String fieldName = "m" + count++;
236 var md = methodTypeDesc(m.getReturnType(), JLRA.getExecutableSharedParameterTypes(m));
237 var thrown = JLRA.getExecutableSharedExceptionTypes(m);
238 var exceptionTypeDescs =
239 thrown.length == 0 ? DEFAULT_RETHROWS
240 : Stream.concat(DEFAULT_RETHROWS.stream(),
241 Arrays.stream(thrown).map(ConstantUtils::referenceClassDesc))
242 .distinct().toList();
243 methods.add(new MethodInfo(md, exceptionTypeDescs, fieldName));
244
245 // find the types referenced by this method
246 addElementType(referencedTypes, m.getReturnType());
247 addElementTypes(referencedTypes, JLRA.getExecutableSharedParameterTypes(m));
248 addElementTypes(referencedTypes, JLRA.getExecutableSharedExceptionTypes(m));
249 }
250
251 if (uniqueName == null)
252 throw newIllegalArgumentException("no method in ", intfc.getName());
253
254 // create a dynamic module for each proxy class, which needs access
255 // to the types referenced by the members of the interface including
256 // the parameter types, return type and exception types
257 var loader = intfc.getClassLoader();
258 Module targetModule = newDynamicModule(loader, referencedTypes);
259
260 // generate a class file in the package of the dynamic module
261 String packageName = targetModule.getName();
262 String intfcName = intfc.getName();
263 int i = intfcName.lastIndexOf('.');
264 // jdk.MHProxy#.Interface
265 String className = packageName + "." + (i > 0 ? intfcName.substring(i + 1) : intfcName);
266 byte[] template = createTemplate(loader, binaryNameToDesc(className),
267 referenceClassDesc(intfc), uniqueName, methods);
268 // define the dynamic module to the class loader of the interface
269 var definer = new Lookup(intfc).makeHiddenClassDefiner(className, template, DUMPER);
270
271 Lookup lookup = definer.defineClassAsLookup(true);
272 // cache the wrapper type
273 var ret = lookup.lookupClass();
274 WRAPPER_TYPES.add(ret);
275 return ret;
276 }
277
278 private static final class WeakReferenceHolder<T> {
279 private volatile WeakReference<T> ref;
280
281 WeakReferenceHolder(T value) {
282 set(value);
283 }
284
285 void set(T value) {
286 ref = new WeakReference<>(value);
287 }
288
289 T get() {
290 return ref.get();
291 }
292 }
293
294 private static Class<?> getProxyClass(Class<?> intfc) {
295 WeakReferenceHolder<Class<?>> r = PROXIES.get(intfc);
296 Class<?> cl = r.get();
297 if (cl != null)
298 return cl;
299
300 // avoid spinning multiple classes in a race
301 synchronized (r) {
302 cl = r.get();
303 if (cl != null)
304 return cl;
305
306 // If the referent is cleared, create a new value and update cached weak reference.
307 cl = newProxyClass(intfc);
308 r.set(cl);
309 return cl;
310 }
311 }
312
313 private static final List<ClassDesc> DEFAULT_RETHROWS = List.of(referenceClassDesc(RuntimeException.class), referenceClassDesc(Error.class));
314 private static final ClassDesc CD_UndeclaredThrowableException = referenceClassDesc(UndeclaredThrowableException.class);
315 private static final ClassDesc CD_IllegalAccessException = referenceClassDesc(IllegalAccessException.class);
316 private static final MethodTypeDesc MTD_void_Throwable = MethodTypeDesc.of(CD_void, CD_Throwable);
317 private static final MethodType MT_void_Lookup_MethodHandle_MethodHandle =
318 methodType(void.class, Lookup.class, MethodHandle.class, MethodHandle.class);
319 private static final MethodType MT_Object_Lookup_MethodHandle_MethodHandle =
320 MT_void_Lookup_MethodHandle_MethodHandle.changeReturnType(Object.class);
321 private static final MethodType MT_MethodHandle_Object = methodType(MethodHandle.class, Object.class);
322 private static final MethodTypeDesc MTD_void_Lookup_MethodHandle_MethodHandle
323 = methodTypeDesc(MT_void_Lookup_MethodHandle_MethodHandle);
324 private static final MethodTypeDesc MTD_void_Lookup = MethodTypeDesc.of(CD_void, CD_MethodHandles_Lookup);
325 private static final MethodTypeDesc MTD_MethodHandle_MethodType = MethodTypeDesc.of(CD_MethodHandle, CD_MethodType);
326 private static final MethodTypeDesc MTD_Class = MethodTypeDesc.of(CD_Class);
327 private static final MethodTypeDesc MTD_int = MethodTypeDesc.of(CD_int);
328 private static final MethodTypeDesc MTD_String = MethodTypeDesc.of(CD_String);
329 private static final MethodTypeDesc MTD_void_String = MethodTypeDesc.of(CD_void, CD_String);
330 private static final String TARGET_NAME = "target";
331 private static final String TYPE_NAME = "interfaceType";
332 private static final String ENSURE_ORIGINAL_LOOKUP = "ensureOriginalLookup";
333
334 /**
335 * Creates an implementation class file for a given interface. One implementation class is
336 * defined for each interface.
337 *
338 * @param ifaceDesc the given interface
339 * @param methodName the name of the single abstract method
340 * @param methods the information for implementation methods
341 * @return the bytes of the implementation classes
342 */
343 private static byte[] createTemplate(ClassLoader loader, ClassDesc proxyDesc, ClassDesc ifaceDesc,
344 String methodName, List<MethodInfo> methods) {
345 return ClassFile.of(ClassHierarchyResolverOption.of(ClassHierarchyResolver.ofClassLoading(loader == null ?
346 ClassLoaders.platformClassLoader() : loader)))
347 .build(proxyDesc, clb -> {
348 clb.withSuperclass(CD_Object)
349 .withFlags((PreviewFeatures.isEnabled() ? ACC_IDENTITY : 0) | ACC_FINAL | ACC_SYNTHETIC)
350 .withInterfaceSymbols(ifaceDesc)
351 // static and instance fields
352 .withField(TYPE_NAME, CD_Class, ACC_PRIVATE | ACC_STATIC | ACC_FINAL)
353 .withField(TARGET_NAME, CD_MethodHandle, ACC_PRIVATE | ACC_FINAL);
354 for (var mi : methods) {
355 clb.withField(mi.fieldName, CD_MethodHandle, ACC_PRIVATE | ACC_FINAL);
356 }
357
358 // <clinit>
359 clb.withMethodBody(CLASS_INIT_NAME, MTD_void, ACC_STATIC, cob -> {
360 cob.loadConstant(ifaceDesc)
361 .putstatic(proxyDesc, TYPE_NAME, CD_Class)
362 .return_();
363 });
364
365 // <init>(Lookup, MethodHandle target, MethodHandle callerBoundTarget)
366 clb.withMethodBody(INIT_NAME, MTD_void_Lookup_MethodHandle_MethodHandle, 0, cob -> {
367 cob.aload(0)
368 .invokespecial(CD_Object, INIT_NAME, MTD_void)
369 // call ensureOriginalLookup to verify the given Lookup has access
370 .aload(1)
371 .invokestatic(proxyDesc, ENSURE_ORIGINAL_LOOKUP, MTD_void_Lookup)
372 // this.target = target;
373 .aload(0)
374 .aload(2)
375 .putfield(proxyDesc, TARGET_NAME, CD_MethodHandle);
376
377 // method handles adjusted to the method type of each method
378 for (var mi : methods) {
379 // this.m<i> = callerBoundTarget.asType(xxType);
380 cob.aload(0)
381 .aload(3)
382 .loadConstant(mi.desc)
383 .invokevirtual(CD_MethodHandle, "asType", MTD_MethodHandle_MethodType)
384 .putfield(proxyDesc, mi.fieldName, CD_MethodHandle);
385 }
386
387 // complete
388 cob.return_();
389 });
390
391 // private static void ensureOriginalLookup(Lookup) checks if the given Lookup
392 // has ORIGINAL access to this class, i.e. the lookup class is this class;
393 // otherwise, IllegalAccessException is thrown
394 clb.withMethodBody(ENSURE_ORIGINAL_LOOKUP, MTD_void_Lookup, ACC_PRIVATE | ACC_STATIC, cob -> {
395 var failLabel = cob.newLabel();
396 // check lookupClass
397 cob.aload(0)
398 .invokevirtual(CD_MethodHandles_Lookup, "lookupClass", MTD_Class)
399 .loadConstant(proxyDesc)
400 .if_acmpne(failLabel)
401 // check original access
402 .aload(0)
403 .invokevirtual(CD_MethodHandles_Lookup, "lookupModes", MTD_int)
404 .loadConstant(Lookup.ORIGINAL)
405 .iand()
406 .ifeq(failLabel)
407 // success
408 .return_()
409 // throw exception
410 .labelBinding(failLabel)
411 .new_(CD_IllegalAccessException)
412 .dup()
413 .aload(0) // lookup
414 .invokevirtual(CD_Object, "toString", MTD_String)
415 .invokespecial(CD_IllegalAccessException, INIT_NAME, MTD_void_String)
416 .athrow();
417 });
418
419 // implementation methods
420 for (MethodInfo mi : methods) {
421 // no need to generate thrown exception attribute
422 clb.withMethodBody(methodName, mi.desc, ACC_PUBLIC, cob -> cob
423 .trying(bcb -> {
424 // return this.handleField.invokeExact(arguments...);
425 bcb.aload(0)
426 .getfield(proxyDesc, mi.fieldName, CD_MethodHandle);
427 for (int j = 0; j < mi.desc.parameterCount(); j++) {
428 bcb.loadLocal(TypeKind.from(mi.desc.parameterType(j)),
429 bcb.parameterSlot(j));
430 }
431 bcb.invokevirtual(CD_MethodHandle, "invokeExact", mi.desc)
432 .return_(TypeKind.from(mi.desc.returnType()));
433 }, ctb -> ctb
434 // catch (Error | RuntimeException | Declared ex) { throw ex; }
435 .catchingMulti(mi.thrown, CodeBuilder::athrow)
436 // catch (Throwable ex) { throw new UndeclaredThrowableException(ex); }
437 .catchingAll(cb -> cb
438 .new_(CD_UndeclaredThrowableException)
439 .dup_x1()
440 .swap()
441 .invokespecial(CD_UndeclaredThrowableException,
442 INIT_NAME, MTD_void_Throwable)
443 .athrow()
444 )
445 ));
446 }
447 });
448 }
449
450 private static MethodHandle bindCaller(MethodHandle target, Class<?> hostClass) {
451 return MethodHandleImpl.bindCaller(target, hostClass).withVarargs(target.isVarargsCollector());
452 }
453
454 /**
455 * Determines if the given object was produced by a call to {@link #asInterfaceInstance asInterfaceInstance}.
456 * @param x any reference
457 * @return true if the reference is not null and points to an object produced by {@code asInterfaceInstance}
458 */
459 public static boolean isWrapperInstance(Object x) {
460 return x != null && WRAPPER_TYPES.contains(x.getClass());
461 }
462
463 /**
464 * Produces or recovers a target method handle which is behaviorally
465 * equivalent to the unique method of this wrapper instance.
466 * The object {@code x} must have been produced by a call to {@link #asInterfaceInstance asInterfaceInstance}.
467 * This requirement may be tested via {@link #isWrapperInstance isWrapperInstance}.
468 * @param x any reference
469 * @return a method handle implementing the unique method
470 * @throws IllegalArgumentException if the reference x is not to a wrapper instance
471 */
472 public static MethodHandle wrapperInstanceTarget(Object x) {
473 if (!isWrapperInstance(x))
474 throw new IllegalArgumentException("not a wrapper instance: " + x);
475
476 try {
477 Class<?> type = x.getClass();
478 MethodHandle getter = new Lookup(type).findGetter(type, TARGET_NAME, MethodHandle.class)
479 .asType(MT_MethodHandle_Object);
480 return (MethodHandle) getter.invokeExact(x);
481 } catch (Throwable ex) {
482 throw uncaughtException(ex);
483 }
484 }
485
486 /**
487 * Recovers the unique single-method interface type for which this wrapper instance was created.
488 * The object {@code x} must have been produced by a call to {@link #asInterfaceInstance asInterfaceInstance}.
489 * This requirement may be tested via {@link #isWrapperInstance isWrapperInstance}.
490 * @param x any reference
491 * @return the single-method interface type for which the wrapper was created
492 * @throws IllegalArgumentException if the reference x is not to a wrapper instance
493 */
494 public static Class<?> wrapperInstanceType(Object x) {
495 if (!isWrapperInstance(x))
496 throw new IllegalArgumentException("not a wrapper instance: " + x);
497
498 try {
499 Class<?> type = x.getClass();
500 MethodHandle originalTypeField = new Lookup(type).findStaticGetter(type, TYPE_NAME, Class.class);
501 return (Class<?>) originalTypeField.invokeExact();
502 } catch (Throwable e) {
503 throw uncaughtException(e);
504 }
505 }
506
507 private static final JavaLangReflectAccess JLRA = SharedSecrets.getJavaLangReflectAccess();
508 private static final AtomicInteger counter = new AtomicInteger();
509
510 private static String nextModuleName() {
511 return "jdk.MHProxy" + counter.incrementAndGet();
512 }
513
514 /**
515 * Create a dynamic module defined to the given class loader and has
516 * access to the given types.
517 * <p>
518 * The dynamic module contains only one single package named the same as
519 * the name of the dynamic module. It's not exported or open.
520 */
521 private static Module newDynamicModule(ClassLoader ld, Set<Class<?>> types) {
522 Objects.requireNonNull(types);
523
524 // create a dynamic module and setup module access
525 String mn = nextModuleName();
526 ModuleDescriptor descriptor = ModuleDescriptor.newModule(mn, Set.of(SYNTHETIC))
527 .packages(Set.of(mn))
528 .build();
529
530 Module dynModule = Modules.defineModule(ld, descriptor, null);
531 Module javaBase = Object.class.getModule();
532
533 Modules.addReads(dynModule, javaBase);
534 Modules.addOpens(dynModule, mn, javaBase);
535
536 for (Class<?> c : types) {
537 ensureAccess(dynModule, c);
538 }
539 return dynModule;
540 }
541
542 private static boolean isObjectMethod(Method m) {
543 return switch (m.getName()) {
544 case "toString" -> m.getReturnType() == String.class
545 && m.getParameterCount() == 0;
546 case "hashCode" -> m.getReturnType() == int.class
547 && m.getParameterCount() == 0;
548 case "equals" -> m.getReturnType() == boolean.class
549 && m.getParameterCount() == 1
550 && JLRA.getExecutableSharedParameterTypes(m)[0] == Object.class;
551 default -> false;
552 };
553 }
554
555 /*
556 * Ensure the given module can access the given class.
557 */
558 private static void ensureAccess(Module target, Class<?> c) {
559 Module m = c.getModule();
560 // add read edge and qualified export for the target module to access
561 if (!target.canRead(m)) {
562 Modules.addReads(target, m);
563 }
564 String pn = c.getPackageName();
565 if (!m.isExported(pn, target)) {
566 Modules.addExports(m, pn, target);
567 }
568 }
569
570 private static void addElementTypes(Set<Class<?>> types, Class<?>... classes) {
571 for (var cls : classes) {
572 addElementType(types, cls);
573 }
574 }
575
576 private static void addElementType(Set<Class<?>> types, Class<?> cls) {
577 Class<?> e = cls;
578 while (e.isArray()) {
579 e = e.getComponentType();
580 }
581
582 if (!e.isPrimitive()) {
583 types.add(e);
584 }
585 }
586 }