Java example source code file (Test7087570.java)

This example Java source code file (Test7087570.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

class, error, methodhandle, methodtype, ref_getfield, ref_invokeinterface, ref_invokespecial, ref_invokestatic, ref_invokevirtual, ref_newinvokespecial, ref_putfield, reflection, string, testmethoddata, tests, util

The Test7087570.java Java example source code

/*
 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

/* @test
 * @bug 7087570
 * @summary REF_invokeSpecial DMHs (which are unusual) get marked explicitly; tweak the MHI to use this bit
 *
 * @run main Test7087570
 */

import java.lang.invoke.*;
import java.lang.reflect.*;
import java.util.*;

import static java.lang.invoke.MethodHandles.*;
import static java.lang.invoke.MethodType.*;
import static java.lang.invoke.MethodHandleInfo.*;

public class Test7087570 {

    private static final TestMethodData[] TESTS = new TestMethodData[] {
        // field accessors
        data(DummyFieldHolder.class, "instanceField", getterMethodType(String.class), DummyFieldHolder.class, REF_getField),
        data(DummyFieldHolder.class, "instanceField", setterMethodType(String.class), DummyFieldHolder.class, REF_putField),
        data(DummyFieldHolder.class, "staticField", getterMethodType(Integer.class), DummyFieldHolder.class, REF_getStatic),
        data(DummyFieldHolder.class, "staticField", setterMethodType(Integer.class), DummyFieldHolder.class, REF_putStatic),
        data(DummyFieldHolder.class, "instanceByteField", getterMethodType(byte.class), DummyFieldHolder.class, REF_getField),
        data(DummyFieldHolder.class, "instanceByteField", setterMethodType(byte.class), DummyFieldHolder.class, REF_putField),

        // REF_invokeVirtual
        data(Object.class, "hashCode", methodType(int.class), Object.class, REF_invokeVirtual),

        // REF_invokeVirtual strength-reduced to REF_invokeSpecial,
        // test if it normalizes back to REF_invokeVirtual in MethodHandleInfo as expected
        data(String.class, "hashCode", methodType(int.class), String.class, REF_invokeVirtual),

        // REF_invokeStatic
        data(Collections.class, "sort", methodType(void.class, List.class), Collections.class, REF_invokeStatic),
        data(Arrays.class, "asList", methodType(List.class, Object[].class), Arrays.class, REF_invokeStatic), // varargs case

        // REF_invokeSpecial
        data(Object.class, "hashCode", methodType(int.class), Object.class, REF_invokeSpecial),

        // REF_newInvokeSpecial
        data(String.class, "<init>", methodType(void.class, char[].class), String.class, REF_newInvokeSpecial),
        data(DummyFieldHolder.class, "<init>", methodType(void.class, byte.class, Long[].class), DummyFieldHolder.class, REF_newInvokeSpecial), // varargs case

        // REF_invokeInterface
        data(List.class, "size", methodType(int.class), List.class, REF_invokeInterface)
    };

    public static void main(String... args) throws Throwable {
        testWithLookup();
        testWithUnreflect();
    }

    private static void doTest(MethodHandle mh, TestMethodData testMethod) {
        MethodHandleInfo mhi = LOOKUP.revealDirect(mh);

        System.out.printf("%s.%s: %s, nominal refKind: %s, actual refKind: %s\n",
                          testMethod.clazz.getName(), testMethod.name, testMethod.methodType,
                          referenceKindToString(testMethod.referenceKind),
                          referenceKindToString(mhi.getReferenceKind()));
        assertEquals(testMethod.name,           mhi.getName());
        assertEquals(testMethod.methodType,     mhi.getMethodType());
        assertEquals(testMethod.declaringClass, mhi.getDeclaringClass());
        assertEquals(testMethod.referenceKind == REF_invokeSpecial, isInvokeSpecial(mh));
        assertRefKindEquals(testMethod.referenceKind,  mhi.getReferenceKind());
    }

    private static void testWithLookup() throws Throwable {
        for (TestMethodData testMethod : TESTS) {
            MethodHandle mh = lookupFrom(testMethod);
            doTest(mh, testMethod);
        }
    }

    private static void testWithUnreflect() throws Throwable {
        for (TestMethodData testMethod : TESTS) {
            MethodHandle mh = unreflectFrom(testMethod);
            doTest(mh, testMethod);
        }
    }

    private static MethodType getterMethodType(Class<?> clazz) {
        return methodType(clazz);
    }

    private static MethodType setterMethodType(Class<?> clazz) {
        return methodType(void.class, clazz);
    }

    private static final Lookup LOOKUP = lookup();

    private static class TestMethodData {
        final Class<?> clazz;
        final String name;
        final MethodType methodType;
        final Class<?> declaringClass;
        final int referenceKind; // the nominal refKind

        public TestMethodData(Class<?> clazz, String name,
                        MethodType methodType, Class<?> declaringClass,
                        int referenceKind) {
            this.clazz = clazz;
            this.name = name;
            this.methodType = methodType;
            this.declaringClass = declaringClass;
            this.referenceKind = referenceKind;
        }
    }

    private static TestMethodData data(Class<?> clazz, String name,
                                       MethodType methodType, Class<?> declaringClass,
                                       int referenceKind) {
        return new TestMethodData(clazz, name, methodType, declaringClass, referenceKind);
    }

    private static MethodHandle lookupFrom(TestMethodData testMethod)
            throws NoSuchMethodException, NoSuchFieldException, IllegalAccessException {
        switch (testMethod.referenceKind) {
        case REF_getField:
            return LOOKUP.findGetter(testMethod.clazz, testMethod.name, testMethod.methodType.returnType());
        case REF_putField:
            return LOOKUP.findSetter(testMethod.clazz, testMethod.name, testMethod.methodType.parameterType(0));
        case REF_getStatic:
            return LOOKUP.findStaticGetter(testMethod.clazz, testMethod.name, testMethod.methodType.returnType());
        case REF_putStatic:
            return LOOKUP.findStaticSetter(testMethod.clazz, testMethod.name, testMethod.methodType.parameterType(0));
        case REF_invokeVirtual:
        case REF_invokeInterface:
            return LOOKUP.findVirtual(testMethod.clazz, testMethod.name, testMethod.methodType);
        case REF_invokeStatic:
            return LOOKUP.findStatic(testMethod.clazz, testMethod.name, testMethod.methodType);
        case REF_invokeSpecial:
            Class<?> thisClass = LOOKUP.lookupClass();
            MethodHandle smh = LOOKUP.findSpecial(testMethod.clazz, testMethod.name, testMethod.methodType, thisClass);
            noteInvokeSpecial(smh);
            return smh;
        case REF_newInvokeSpecial:
            return LOOKUP.findConstructor(testMethod.clazz, testMethod.methodType);
        default:
            throw new Error("ERROR: unexpected referenceKind in test data");
        }
    }

    private static MethodHandle unreflectFrom(TestMethodData testMethod)
            throws NoSuchMethodException, NoSuchFieldException, IllegalAccessException {
        switch (testMethod.referenceKind) {
        case REF_getField:
        case REF_getStatic: {
                Field f = testMethod.clazz.getDeclaredField(testMethod.name);
                return LOOKUP.unreflectGetter(f);
            }
        case REF_putField:
        case REF_putStatic: {
                Field f = testMethod.clazz.getDeclaredField(testMethod.name);
                return LOOKUP.unreflectSetter(f);
            }
        case REF_invokeVirtual:
        case REF_invokeStatic:
        case REF_invokeInterface: {
                Method m = testMethod.clazz.getDeclaredMethod(testMethod.name, testMethod.methodType.parameterArray());
                return LOOKUP.unreflect(m);
            }
        case REF_invokeSpecial: {
                Method m = testMethod.clazz.getDeclaredMethod(testMethod.name, testMethod.methodType.parameterArray());
                Class<?> thisClass = LOOKUP.lookupClass();
                MethodHandle smh = LOOKUP.unreflectSpecial(m, thisClass);
                noteInvokeSpecial(smh);
                return smh;
            }
        case REF_newInvokeSpecial: {
                Constructor c = testMethod.clazz.getDeclaredConstructor(testMethod.methodType.parameterArray());
                return LOOKUP.unreflectConstructor(c);
            }
        default:
            throw new Error("ERROR: unexpected referenceKind in test data");
        }
    }

    private static List<MethodHandle> specialMethodHandles = new ArrayList<>();
    private static void noteInvokeSpecial(MethodHandle mh) {
        specialMethodHandles.add(mh);
        assert(isInvokeSpecial(mh));
    }
    private static boolean isInvokeSpecial(MethodHandle mh) {
        return specialMethodHandles.contains(mh);
    }

    private static void assertRefKindEquals(int expect, int observed) {
        if (expect == observed) return;

        String msg = "expected " + referenceKindToString(expect) +
                     " but observed " + referenceKindToString(observed);
        System.out.println("FAILED: " + msg);
        throw new AssertionError(msg);
    }

    private static void assertEquals(Object expect, Object observed) {
        if (java.util.Objects.equals(expect, observed)) return;

        String msg = "expected " + expect + " but observed " + observed;
        System.out.println("FAILED: " + msg);
        throw new AssertionError(msg);
    }
}

class DummyFieldHolder {
    public static Integer staticField;
    public String instanceField;
    public byte instanceByteField;

    public DummyFieldHolder(byte unused1, Long... unused2) {
    }
}