Adding the Functions class as a helper for dealing with Java 8 Lambdas.
This commit is contained in:
Jochen Wiedmann (jwi)
parent
b00e65686e
commit
11d9eb47a4
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@ -46,6 +46,7 @@ The <action> type attribute can be add,update,fix,remove.
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<body>
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<release version="3.9" date="????-??-??" description="??">
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<action type="add" dev="jochen">Adding the Functions class.</action>
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<action issue="LANG-1416" type="update" dev="britter">Update to JUnit 5</action>
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<action issue="LANG-1417" type="update" dev="britter">Add @FunctionalInterface to ThreadPredicate and ThreadGroupPredicate</action>
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<action issue="LANG-1415" type="update" dev="britter">Update Java Language requirement to 1.8</action>
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@ -0,0 +1,144 @@
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.lang3;
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import java.io.IOException;
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import java.io.UncheckedIOException;
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import java.lang.reflect.Method;
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import java.lang.reflect.UndeclaredThrowableException;
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import java.util.ArrayList;
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import org.apache.commons.lang3.exception.ExceptionUtils;
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/** This class provides utility functions, and classes for working with the
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* {@code java.util.function} package, or more generally, with Java 8
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* lambdas.
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* More specifically, it attempts to address the fact that lambdas are supposed
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* not to throw Exceptions, at least not checked Exceptions, aka instances of
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* {@link Exception}. This enforces the use of constructs like
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* <pre>
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* Consumer<java.lang.reflect.Method> consumer = (m) -> {
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* try {
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* m.invoke(o, args);
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* } catch (Throwable t) {
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* throw Functions.rethrow(t);
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* }
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* };
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* </pre>
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* By replacing a {@link Consumer Consumer<O>} with a
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* {@link FailableConsumer FailableConsumer<O,? extends Throwable}, this can be
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* written like follows:
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* <pre>
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* Functions.accept((m) -> m.invoke(o,args));
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* </pre>
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* Obviously, the second version is much more concise and the spirit of
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* Lambda expressions is met better than the second version.
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*/
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public class Functions {
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@FunctionalInterface
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public interface FailableRunnable<T extends Throwable> {
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public void run() throws T;
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}
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@FunctionalInterface
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public interface FailableCallable<O,T extends Throwable> {
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public O call() throws T;
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}
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@FunctionalInterface
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public interface FailableConsumer<O,T extends Throwable> {
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public void accept(O pObject) throws T;
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}
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@FunctionalInterface
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public interface FailableBiConsumer<O1,O2,T extends Throwable> {
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public void accept(O1 pObject1, O2 pObject2) throws T;
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}
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@FunctionalInterface
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public interface FailableFunction<I,O,T extends Throwable> {
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public O apply(I pInput) throws T;
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}
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@FunctionalInterface
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public interface FailableBiFunction<I1,I2,O,T extends Throwable> {
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public O apply(I1 pInput1, I2 pInput2) throws T;
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}
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public static <T extends Throwable> void run(FailableRunnable<T> pRunnable) {
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try {
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pRunnable.run();
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} catch (Throwable t) {
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throw rethrow(t);
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}
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}
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public static <O,T extends Throwable> O call(FailableCallable<O,T> pCallable) {
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try {
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return pCallable.call();
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} catch (Throwable t) {
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throw rethrow(t);
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}
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}
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public static <O,T extends Throwable> void accept(FailableConsumer<O,T> pConsumer, O pObject) {
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try {
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pConsumer.accept(pObject);
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} catch (Throwable t) {
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throw rethrow(t);
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}
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}
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public static <O1,O2,T extends Throwable> void accept(FailableBiConsumer<O1,O2,T> pConsumer, O1 pObject1, O2 pObject2) {
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try {
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pConsumer.accept(pObject1, pObject2);
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} catch (Throwable t) {
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throw rethrow(t);
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}
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}
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public static <I,O,T extends Throwable> O apply(FailableFunction<I,O,T> pFunction, I pInput) {
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try {
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return pFunction.apply(pInput);
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} catch (Throwable t) {
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throw rethrow(t);
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}
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}
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public static <I1,I2,O,T extends Throwable> O apply(FailableBiFunction<I1,I2,O,T> pFunction, I1 pInput1, I2 pInput2) {
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try {
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return pFunction.apply(pInput1, pInput2);
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} catch (Throwable t) {
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throw rethrow(t);
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}
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}
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public static RuntimeException rethrow(Throwable pThrowable) {
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if (pThrowable == null) {
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throw new NullPointerException("The Throwable must not be null.");
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} else {
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if (pThrowable instanceof RuntimeException) {
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throw (RuntimeException) pThrowable;
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} else if (pThrowable instanceof Error) {
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throw (Error) pThrowable;
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} else if (pThrowable instanceof IOException) {
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throw new UncheckedIOException((IOException) pThrowable);
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} else {
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throw new UndeclaredThrowableException(pThrowable);
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}
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}
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}
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public static void test() throws Exception {
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run(() -> ArrayList.class.newInstance());
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}
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}
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@ -0,0 +1,232 @@
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package org.apache.commons.lang3;
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import static org.junit.jupiter.api.Assertions.*;
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import java.io.IOException;
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import java.io.UncheckedIOException;
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import java.lang.reflect.UndeclaredThrowableException;
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import org.junit.jupiter.api.Test;
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class FunctionsTest {
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public static class SomeException extends Exception {
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private static final long serialVersionUID = -4965704778119283411L;
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private Throwable t;
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public SomeException(String pMsg) {
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super(pMsg);
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}
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public void setThrowable(Throwable pThrowable) {
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t = pThrowable;
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}
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public void test() throws Throwable {
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if (t != null) {
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throw t;
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}
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}
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}
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public static class Testable {
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private Throwable t;
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public Testable(Throwable pTh) {
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t = pTh;
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}
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public void setThrowable(Throwable pThrowable) {
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t = pThrowable;
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}
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public void test() throws Throwable {
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test(t);
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}
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public void test(Throwable pThrowable) throws Throwable {
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if (pThrowable != null) {
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throw pThrowable;
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}
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}
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public Integer testInt() throws Throwable {
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return testInt(t);
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}
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public Integer testInt(Throwable pThrowable) throws Throwable {
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if (pThrowable != null) {
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throw pThrowable;
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}
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return 0;
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}
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}
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public static class FailureOnOddInvocations {
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private static int invocation;
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public FailureOnOddInvocations() throws SomeException {
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final int i = ++invocation;
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if (i % 2 == 1) {
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throw new SomeException("Odd Invocation: " + i);
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}
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}
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}
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@Test
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void testRunnable() {
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FailureOnOddInvocations.invocation = 0;
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try {
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Functions.run(() -> new FailureOnOddInvocations());
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fail("Expected Exception");
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} catch (UndeclaredThrowableException e) {
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final Throwable cause = e.getCause();
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assertNotNull(cause);
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assertTrue(cause instanceof SomeException);
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assertEquals("Odd Invocation: 1", cause.getMessage());
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}
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Functions.run(() -> new FailureOnOddInvocations());
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}
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@Test
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void testCallable() {
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FailureOnOddInvocations.invocation = 0;
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try {
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Functions.call(() -> new FailureOnOddInvocations());
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fail("Expected Exception");
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} catch (UndeclaredThrowableException e) {
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final Throwable cause = e.getCause();
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assertNotNull(cause);
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assertTrue(cause instanceof SomeException);
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assertEquals("Odd Invocation: 1", cause.getMessage());
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}
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final FailureOnOddInvocations instance = Functions.call(() -> new FailureOnOddInvocations());
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assertNotNull(instance);
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}
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@Test
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void testAcceptConsumer() {
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final IllegalStateException ise = new IllegalStateException();
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final Testable testable = new Testable(ise);
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try {
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Functions.accept((t) -> t.test(), testable);
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fail("Expected Exception");
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} catch (IllegalStateException e) {
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assertSame(ise, e);
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}
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final Error error = new OutOfMemoryError();
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testable.setThrowable(error);
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try {
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Functions.accept((t) -> t.test(), testable);
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} catch (OutOfMemoryError e) {
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assertSame(error, e);
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}
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final IOException ioe = new IOException("Unknown I/O error");
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testable.setThrowable(ioe);
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try {
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Functions.accept((t) -> t.test(), testable);
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fail("Expected Exception");
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} catch (UncheckedIOException e) {
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final Throwable t = e.getCause();
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assertNotNull(t);
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assertTrue(t instanceof IOException);
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assertSame(ioe, t);
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}
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testable.setThrowable(null);
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Functions.accept((t) -> t.test(), testable);
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}
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@Test
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void testAcceptBiConsumer() {
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final IllegalStateException ise = new IllegalStateException();
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final Testable testable = new Testable(null);
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try {
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Functions.accept((t1,t2) -> t1.test(t2), testable, ise);
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fail("Expected Exception");
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} catch (IllegalStateException e) {
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assertSame(ise, e);
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}
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final Error error = new OutOfMemoryError();
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try {
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Functions.accept((t1,t2) -> t1.test(t2), testable, error);
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} catch (OutOfMemoryError e) {
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assertSame(error, e);
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}
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final IOException ioe = new IOException("Unknown I/O error");
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testable.setThrowable(ioe);
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try {
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Functions.accept((t1,t2) -> t1.test(t2), testable, ioe);
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fail("Expected Exception");
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} catch (UncheckedIOException e) {
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final Throwable t = e.getCause();
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assertNotNull(t);
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assertTrue(t instanceof IOException);
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assertSame(ioe, t);
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}
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testable.setThrowable(null);
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Functions.accept((t1,t2) -> t1.test(t2), testable, (Throwable) null);
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}
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@Test
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public void testApplyFunction() {
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final IllegalStateException ise = new IllegalStateException();
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final Testable testable = new Testable(ise);
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try {
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Functions.apply((t) -> t.testInt(), testable);
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fail("Expected Exception");
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} catch (IllegalStateException e) {
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assertSame(ise, e);
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}
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final Error error = new OutOfMemoryError();
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testable.setThrowable(error);
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try {
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Functions.apply((t) -> t.testInt(), testable);
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} catch (OutOfMemoryError e) {
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assertSame(error, e);
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}
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final IOException ioe = new IOException("Unknown I/O error");
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testable.setThrowable(ioe);
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try {
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Functions.apply((t) -> t.testInt(), testable);
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fail("Expected Exception");
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} catch (UncheckedIOException e) {
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final Throwable t = e.getCause();
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assertNotNull(t);
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assertTrue(t instanceof IOException);
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assertSame(ioe, t);
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}
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testable.setThrowable(null);
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final Integer i = Functions.apply((t) -> t.testInt(), testable);
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assertNotNull(i);
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assertEquals(0, i.intValue());
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}
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@Test
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public void testApplyBiFunction() {
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final IllegalStateException ise = new IllegalStateException();
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final Testable testable = new Testable(null);
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try {
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Functions.apply((t1,t2) -> t1.testInt(t2), testable, ise);
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fail("Expected Exception");
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} catch (IllegalStateException e) {
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assertSame(ise, e);
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}
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final Error error = new OutOfMemoryError();
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try {
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Functions.apply((t1,t2) -> t1.testInt(t2), testable, error);
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} catch (OutOfMemoryError e) {
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assertSame(error, e);
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}
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final IOException ioe = new IOException("Unknown I/O error");
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try {
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Functions.apply((t1,t2) -> t1.testInt(t2), testable, ioe);
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fail("Expected Exception");
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} catch (UncheckedIOException e) {
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final Throwable t = e.getCause();
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assertNotNull(t);
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assertTrue(t instanceof IOException);
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assertSame(ioe, t);
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}
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final Integer i = Functions.apply((t1,t2) -> t1.testInt(t2), testable, (Throwable) null);
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assertNotNull(i);
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assertEquals(0, i.intValue());
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}
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}
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