2644 * If the returned method handle is invoked, the constructor's class will
2645 * be initialized, if it has not already been initialized.
2646 * <p><b>Example:</b>
2647 * {@snippet lang="java" :
2648 import static java.lang.invoke.MethodHandles.*;
2649 import static java.lang.invoke.MethodType.*;
2650 ...
2651 MethodHandle MH_newArrayList = publicLookup().findConstructor(
2652 ArrayList.class, methodType(void.class, Collection.class));
2653 Collection orig = Arrays.asList("x", "y");
2654 Collection copy = (ArrayList) MH_newArrayList.invokeExact(orig);
2655 assert(orig != copy);
2656 assertEquals(orig, copy);
2657 // a variable-arity constructor:
2658 MethodHandle MH_newProcessBuilder = publicLookup().findConstructor(
2659 ProcessBuilder.class, methodType(void.class, String[].class));
2660 ProcessBuilder pb = (ProcessBuilder)
2661 MH_newProcessBuilder.invoke("x", "y", "z");
2662 assertEquals("[x, y, z]", pb.command().toString());
2663 * }
2664 * @param refc the class or interface from which the method is accessed
2665 * @param type the type of the method, with the receiver argument omitted, and a void return type
2666 * @return the desired method handle
2667 * @throws NoSuchMethodException if the constructor does not exist
2668 * @throws IllegalAccessException if access checking fails
2669 * or if the method's variable arity modifier bit
2670 * is set and {@code asVarargsCollector} fails
2671 * @throws NullPointerException if any argument is null
2672 */
2673 public MethodHandle findConstructor(Class<?> refc, MethodType type) throws NoSuchMethodException, IllegalAccessException {
2674 if (refc.isArray()) {
2675 throw new NoSuchMethodException("no constructor for array class: " + refc.getName());
2676 }
2677 String name = ConstantDescs.INIT_NAME;
2678 MemberName ctor = resolveOrFail(REF_newInvokeSpecial, refc, name, type);
2679 return getDirectConstructor(refc, ctor);
2680 }
2681
2682 /**
2683 * Looks up a class by name from the lookup context defined by this {@code Lookup} object,
2684 * <a href="MethodHandles.Lookup.html#equiv">as if resolved</a> by an {@code ldc} instruction.
2685 * Such a resolution, as specified in JVMS {@jvms 5.4.3.1}, attempts to locate and load the class,
2686 * and then determines whether the class is accessible to this lookup object.
2687 * <p>
2688 * For a class or an interface, the name is the {@linkplain ClassLoader##binary-name binary name}.
2689 * For an array class of {@code n} dimensions, the name begins with {@code n} occurrences
2690 * of {@code '['} and followed by the element type as encoded in the
2691 * {@linkplain Class##nameFormat table} specified in {@link Class#getName}.
2692 * <p>
2693 * The lookup context here is determined by the {@linkplain #lookupClass() lookup class},
2694 * its class loader, and the {@linkplain #lookupModes() lookup modes}.
2695 *
2696 * @param targetName the {@linkplain ClassLoader##binary-name binary name} of the class
3823 assert(mh.viewAsTypeChecks(narrowType, true));
3824 return mh.copyWith(narrowType, mh.form);
3825 }
3826
3827 /** Check access and get the requested method. */
3828 private MethodHandle getDirectMethod(byte refKind, Class<?> refc, MemberName method, Lookup callerLookup) throws IllegalAccessException {
3829 final boolean doRestrict = true;
3830 return getDirectMethodCommon(refKind, refc, method, doRestrict, callerLookup);
3831 }
3832 /** Check access and get the requested method, for invokespecial with no restriction on the application of narrowing rules. */
3833 private MethodHandle getDirectMethodNoRestrictInvokeSpecial(Class<?> refc, MemberName method, Lookup callerLookup) throws IllegalAccessException {
3834 final boolean doRestrict = false;
3835 return getDirectMethodCommon(REF_invokeSpecial, refc, method, doRestrict, callerLookup);
3836 }
3837 /** Common code for all methods; do not call directly except from immediately above. */
3838 private MethodHandle getDirectMethodCommon(byte refKind, Class<?> refc, MemberName method,
3839 boolean doRestrict,
3840 Lookup boundCaller) throws IllegalAccessException {
3841 checkMethod(refKind, refc, method);
3842 assert(!method.isMethodHandleInvoke());
3843
3844 if (refKind == REF_invokeSpecial &&
3845 refc != lookupClass() &&
3846 !refc.isInterface() && !lookupClass().isInterface() &&
3847 refc != lookupClass().getSuperclass() &&
3848 refc.isAssignableFrom(lookupClass())) {
3849 assert(!method.getName().equals(ConstantDescs.INIT_NAME)); // not this code path
3850
3851 // Per JVMS 6.5, desc. of invokespecial instruction:
3852 // If the method is in a superclass of the LC,
3853 // and if our original search was above LC.super,
3854 // repeat the search (symbolic lookup) from LC.super
3855 // and continue with the direct superclass of that class,
3856 // and so forth, until a match is found or no further superclasses exist.
3857 // FIXME: MemberName.resolve should handle this instead.
3858 Class<?> refcAsSuper = lookupClass();
3859 MemberName m2;
3860 do {
3861 refcAsSuper = refcAsSuper.getSuperclass();
3862 m2 = new MemberName(refcAsSuper,
3863 method.getName(),
|
2644 * If the returned method handle is invoked, the constructor's class will
2645 * be initialized, if it has not already been initialized.
2646 * <p><b>Example:</b>
2647 * {@snippet lang="java" :
2648 import static java.lang.invoke.MethodHandles.*;
2649 import static java.lang.invoke.MethodType.*;
2650 ...
2651 MethodHandle MH_newArrayList = publicLookup().findConstructor(
2652 ArrayList.class, methodType(void.class, Collection.class));
2653 Collection orig = Arrays.asList("x", "y");
2654 Collection copy = (ArrayList) MH_newArrayList.invokeExact(orig);
2655 assert(orig != copy);
2656 assertEquals(orig, copy);
2657 // a variable-arity constructor:
2658 MethodHandle MH_newProcessBuilder = publicLookup().findConstructor(
2659 ProcessBuilder.class, methodType(void.class, String[].class));
2660 ProcessBuilder pb = (ProcessBuilder)
2661 MH_newProcessBuilder.invoke("x", "y", "z");
2662 assertEquals("[x, y, z]", pb.command().toString());
2663 * }
2664 *
2665 *
2666 * @param refc the class or interface from which the method is accessed
2667 * @param type the type of the method, with the receiver argument omitted, and a void return type
2668 * @return the desired method handle
2669 * @throws NoSuchMethodException if the constructor does not exist
2670 * @throws IllegalAccessException if access checking fails
2671 * or if the method's variable arity modifier bit
2672 * is set and {@code asVarargsCollector} fails
2673 * @throws NullPointerException if any argument is null
2674 */
2675 public MethodHandle findConstructor(Class<?> refc, MethodType type) throws NoSuchMethodException, IllegalAccessException {
2676 if (refc.isArray()) {
2677 throw new NoSuchMethodException("no constructor for array class: " + refc.getName());
2678 }
2679 if (type.returnType() != void.class) {
2680 throw new NoSuchMethodException("Constructors must have void return type: " + refc.getName());
2681 }
2682 String name = ConstantDescs.INIT_NAME;
2683 MemberName ctor = resolveOrFail(REF_newInvokeSpecial, refc, name, type);
2684 return getDirectConstructor(refc, ctor);
2685 }
2686
2687 /**
2688 * Looks up a class by name from the lookup context defined by this {@code Lookup} object,
2689 * <a href="MethodHandles.Lookup.html#equiv">as if resolved</a> by an {@code ldc} instruction.
2690 * Such a resolution, as specified in JVMS {@jvms 5.4.3.1}, attempts to locate and load the class,
2691 * and then determines whether the class is accessible to this lookup object.
2692 * <p>
2693 * For a class or an interface, the name is the {@linkplain ClassLoader##binary-name binary name}.
2694 * For an array class of {@code n} dimensions, the name begins with {@code n} occurrences
2695 * of {@code '['} and followed by the element type as encoded in the
2696 * {@linkplain Class##nameFormat table} specified in {@link Class#getName}.
2697 * <p>
2698 * The lookup context here is determined by the {@linkplain #lookupClass() lookup class},
2699 * its class loader, and the {@linkplain #lookupModes() lookup modes}.
2700 *
2701 * @param targetName the {@linkplain ClassLoader##binary-name binary name} of the class
3828 assert(mh.viewAsTypeChecks(narrowType, true));
3829 return mh.copyWith(narrowType, mh.form);
3830 }
3831
3832 /** Check access and get the requested method. */
3833 private MethodHandle getDirectMethod(byte refKind, Class<?> refc, MemberName method, Lookup callerLookup) throws IllegalAccessException {
3834 final boolean doRestrict = true;
3835 return getDirectMethodCommon(refKind, refc, method, doRestrict, callerLookup);
3836 }
3837 /** Check access and get the requested method, for invokespecial with no restriction on the application of narrowing rules. */
3838 private MethodHandle getDirectMethodNoRestrictInvokeSpecial(Class<?> refc, MemberName method, Lookup callerLookup) throws IllegalAccessException {
3839 final boolean doRestrict = false;
3840 return getDirectMethodCommon(REF_invokeSpecial, refc, method, doRestrict, callerLookup);
3841 }
3842 /** Common code for all methods; do not call directly except from immediately above. */
3843 private MethodHandle getDirectMethodCommon(byte refKind, Class<?> refc, MemberName method,
3844 boolean doRestrict,
3845 Lookup boundCaller) throws IllegalAccessException {
3846 checkMethod(refKind, refc, method);
3847 assert(!method.isMethodHandleInvoke());
3848 if (refKind == REF_invokeSpecial &&
3849 refc != lookupClass() &&
3850 !refc.isInterface() && !lookupClass().isInterface() &&
3851 refc != lookupClass().getSuperclass() &&
3852 refc.isAssignableFrom(lookupClass())) {
3853 assert(!method.getName().equals(ConstantDescs.INIT_NAME)); // not this code path
3854
3855 // Per JVMS 6.5, desc. of invokespecial instruction:
3856 // If the method is in a superclass of the LC,
3857 // and if our original search was above LC.super,
3858 // repeat the search (symbolic lookup) from LC.super
3859 // and continue with the direct superclass of that class,
3860 // and so forth, until a match is found or no further superclasses exist.
3861 // FIXME: MemberName.resolve should handle this instead.
3862 Class<?> refcAsSuper = lookupClass();
3863 MemberName m2;
3864 do {
3865 refcAsSuper = refcAsSuper.getSuperclass();
3866 m2 = new MemberName(refcAsSuper,
3867 method.getName(),
|