All Downloads are FREE. Search and download functionalities are using the official Maven repository.

org.apache.commons.lang3.function.Failable Maven / Gradle / Ivy

There is a newer version: 4.1.4
Show newest version
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.lang3.function;

import java.io.IOException;
import java.io.UncheckedIOException;
import java.lang.reflect.UndeclaredThrowableException;
import java.util.Collection;
import java.util.Objects;
import java.util.concurrent.Callable;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.BiPredicate;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.stream.Stream;

import org.apache.commons.lang3.stream.Streams.FailableStream;

/**
 * This class provides utility functions, and classes for working with the {@code java.util.function} package, or more
 * generally, with Java 8 lambdas. More specifically, it attempts to address the fact that lambdas are supposed not to
 * throw Exceptions, at least not checked Exceptions, AKA instances of {@link Exception}. This enforces the use of
 * constructs like:
 *
 * 
 * Consumer<java.lang.reflect.Method-> consumer = m -> {
 *     try {
 *         m.invoke(o, args);
 *     } catch (Throwable t) {
 *         throw Failable.rethrow(t);
 *     }
 * };
 * 
* *

* By replacing a {@link java.util.function.Consumer Consumer<O>} with a {@link FailableConsumer * FailableConsumer<O,? extends Throwable>}, this can be written like follows: *

* *
 * Functions.accept((m) -> m.invoke(o, args));
 * 
* *

* Obviously, the second version is much more concise and the spirit of Lambda expressions is met better than the second * version. *

* * @since 3.11 */ public class Failable { /** * Consumes a consumer and rethrows any exception as a {@link RuntimeException}. * * @param consumer the consumer to consume * @param object1 the first object to consume by {@code consumer} * @param object2 the second object to consume by {@code consumer} * @param the type of the first argument the consumer accepts * @param the type of the second argument the consumer accepts * @param the type of checked exception the consumer may throw */ public static void accept(final FailableBiConsumer consumer, final T object1, final U object2) { run(() -> consumer.accept(object1, object2)); } /** * Consumes a consumer and rethrows any exception as a {@link RuntimeException}. * * @param consumer the consumer to consume * @param object the object to consume by {@code consumer} * @param the type the consumer accepts * @param the type of checked exception the consumer may throw */ public static void accept(final FailableConsumer consumer, final T object) { run(() -> consumer.accept(object)); } /** * Consumes a consumer and rethrows any exception as a {@link RuntimeException}. * * @param consumer the consumer to consume * @param value the value to consume by {@code consumer} * @param the type of checked exception the consumer may throw */ public static void accept(final FailableDoubleConsumer consumer, final double value) { run(() -> consumer.accept(value)); } /** * Consumes a consumer and rethrows any exception as a {@link RuntimeException}. * * @param consumer the consumer to consume * @param value the value to consume by {@code consumer} * @param the type of checked exception the consumer may throw */ public static void accept(final FailableIntConsumer consumer, final int value) { run(() -> consumer.accept(value)); } /** * Consumes a consumer and rethrows any exception as a {@link RuntimeException}. * * @param consumer the consumer to consume * @param value the value to consume by {@code consumer} * @param the type of checked exception the consumer may throw */ public static void accept(final FailableLongConsumer consumer, final long value) { run(() -> consumer.accept(value)); } /** * Applies a function and rethrows any exception as a {@link RuntimeException}. * * @param function the function to apply * @param input1 the first input to apply {@code function} on * @param input2 the second input to apply {@code function} on * @param the type of the first argument the function accepts * @param the type of the second argument the function accepts * @param the return type of the function * @param the type of checked exception the function may throw * @return the value returned from the function */ public static R apply(final FailableBiFunction function, final T input1, final U input2) { return get(() -> function.apply(input1, input2)); } /** * Applies a function and rethrows any exception as a {@link RuntimeException}. * * @param function the function to apply * @param input the input to apply {@code function} on * @param the type of the argument the function accepts * @param the return type of the function * @param the type of checked exception the function may throw * @return the value returned from the function */ public static R apply(final FailableFunction function, final T input) { return get(() -> function.apply(input)); } /** * Applies a function and rethrows any exception as a {@link RuntimeException}. * * @param function the function to apply * @param left the first input to apply {@code function} on * @param right the second input to apply {@code function} on * @param the type of checked exception the function may throw * @return the value returned from the function */ public static double applyAsDouble(final FailableDoubleBinaryOperator function, final double left, final double right) { return getAsDouble(() -> function.applyAsDouble(left, right)); } /** * Converts the given {@link FailableBiConsumer} into a standard {@link BiConsumer}. * * @param the type of the first argument of the consumers * @param the type of the second argument of the consumers * @param consumer a failable {@code BiConsumer} * @return a standard {@code BiConsumer} */ public static BiConsumer asBiConsumer(final FailableBiConsumer consumer) { return (input1, input2) -> accept(consumer, input1, input2); } /** * Converts the given {@link FailableBiFunction} into a standard {@link BiFunction}. * * @param the type of the first argument of the input of the functions * @param the type of the second argument of the input of the functions * @param the type of the output of the functions * @param function a {@code FailableBiFunction} * @return a standard {@code BiFunction} */ public static BiFunction asBiFunction(final FailableBiFunction function) { return (input1, input2) -> apply(function, input1, input2); } /** * Converts the given {@link FailableBiPredicate} into a standard {@link BiPredicate}. * * @param the type of the first argument used by the predicates * @param the type of the second argument used by the predicates * @param predicate a {@code FailableBiPredicate} * @return a standard {@code BiPredicate} */ public static BiPredicate asBiPredicate(final FailableBiPredicate predicate) { return (input1, input2) -> test(predicate, input1, input2); } /** * Converts the given {@link FailableCallable} into a standard {@link Callable}. * * @param the type used by the callables * @param callable a {@code FailableCallable} * @return a standard {@code Callable} */ public static Callable asCallable(final FailableCallable callable) { return () -> call(callable); } /** * Converts the given {@link FailableConsumer} into a standard {@link Consumer}. * * @param the type used by the consumers * @param consumer a {@code FailableConsumer} * @return a standard {@code Consumer} */ public static Consumer asConsumer(final FailableConsumer consumer) { return input -> accept(consumer, input); } /** * Converts the given {@link FailableFunction} into a standard {@link Function}. * * @param the type of the input of the functions * @param the type of the output of the functions * @param function a {code FailableFunction} * @return a standard {@code Function} */ public static Function asFunction(final FailableFunction function) { return input -> apply(function, input); } /** * Converts the given {@link FailablePredicate} into a standard {@link Predicate}. * * @param the type used by the predicates * @param predicate a {@code FailablePredicate} * @return a standard {@code Predicate} */ public static Predicate asPredicate(final FailablePredicate predicate) { return input -> test(predicate, input); } /** * Converts the given {@link FailableRunnable} into a standard {@link Runnable}. * * @param runnable a {@code FailableRunnable} * @return a standard {@code Runnable} */ public static Runnable asRunnable(final FailableRunnable runnable) { return () -> run(runnable); } /** * Converts the given {@link FailableSupplier} into a standard {@link Supplier}. * * @param the type supplied by the suppliers * @param supplier a {@code FailableSupplier} * @return a standard {@code Supplier} */ public static Supplier asSupplier(final FailableSupplier supplier) { return () -> get(supplier); } /** * Calls a callable and rethrows any exception as a {@link RuntimeException}. * * @param callable the callable to call * @param the return type of the callable * @param the type of checked exception the callable may throw * @return the value returned from the callable */ public static V call(final FailableCallable callable) { return get(callable::call); } /** * Invokes a supplier, and returns the result. * * @param supplier The supplier to invoke. * @param The suppliers output type. * @param The type of checked exception, which the supplier can throw. * @return The object, which has been created by the supplier */ public static T get(final FailableSupplier supplier) { try { return supplier.get(); } catch (final Throwable t) { throw rethrow(t); } } /** * Invokes a boolean supplier, and returns the result. * * @param supplier The boolean supplier to invoke. * @param The type of checked exception, which the supplier can throw. * @return The boolean, which has been created by the supplier */ public static boolean getAsBoolean(final FailableBooleanSupplier supplier) { try { return supplier.getAsBoolean(); } catch (final Throwable t) { throw rethrow(t); } } /** * Invokes a double supplier, and returns the result. * * @param supplier The double supplier to invoke. * @param The type of checked exception, which the supplier can throw. * @return The double, which has been created by the supplier */ public static double getAsDouble(final FailableDoubleSupplier supplier) { try { return supplier.getAsDouble(); } catch (final Throwable t) { throw rethrow(t); } } /** * Invokes an int supplier, and returns the result. * * @param supplier The int supplier to invoke. * @param The type of checked exception, which the supplier can throw. * @return The int, which has been created by the supplier */ public static int getAsInt(final FailableIntSupplier supplier) { try { return supplier.getAsInt(); } catch (final Throwable t) { throw rethrow(t); } } /** * Invokes a long supplier, and returns the result. * * @param supplier The long supplier to invoke. * @param The type of checked exception, which the supplier can throw. * @return The long, which has been created by the supplier */ public static long getAsLong(final FailableLongSupplier supplier) { try { return supplier.getAsLong(); } catch (final Throwable t) { throw rethrow(t); } } /** * Invokes a short supplier, and returns the result. * * @param supplier The short supplier to invoke. * @param The type of checked exception, which the supplier can throw. * @return The short, which has been created by the supplier */ public static short getAsShort(final FailableShortSupplier supplier) { try { return supplier.getAsShort(); } catch (final Throwable t) { throw rethrow(t); } } /** *

* Rethrows a {@link Throwable} as an unchecked exception. If the argument is already unchecked, namely a * {@code RuntimeException} or {@code Error} then the argument will be rethrown without modification. If the * exception is {@code IOException} then it will be wrapped into a {@code UncheckedIOException}. In every other * cases the exception will be wrapped into a {@code * UndeclaredThrowableException} *

* *

* Note that there is a declared return type for this method, even though it never returns. The reason for that is * to support the usual pattern: *

* *
     * throw rethrow(myUncheckedException);
     * 
* *

* instead of just calling the method. This pattern may help the Java compiler to recognize that at that point an * exception will be thrown and the code flow analysis will not demand otherwise mandatory commands that could * follow the method call, like a {@code return} statement from a value returning method. *

* * @param throwable The throwable to rethrow ossibly wrapped into an unchecked exception * @return Never returns anything, this method never terminates normally. */ public static RuntimeException rethrow(final Throwable throwable) { Objects.requireNonNull(throwable, "throwable"); if (throwable instanceof RuntimeException) { throw (RuntimeException) throwable; } else if (throwable instanceof Error) { throw (Error) throwable; } else if (throwable instanceof IOException) { throw new UncheckedIOException((IOException) throwable); } else { throw new UndeclaredThrowableException(throwable); } } /** * Runs a runnable and rethrows any exception as a {@link RuntimeException}. * * @param runnable The runnable to run * @param the type of checked exception the runnable may throw */ public static void run(final FailableRunnable runnable) { try { runnable.run(); } catch (final Throwable t) { throw rethrow(t); } } /** * Converts the given collection into a {@link FailableStream}. The {@link FailableStream} consists of the * collections elements. Shortcut for * *
     * Functions.stream(collection.stream());
     * 
* * @param collection The collection, which is being converted into a {@link FailableStream}. * @param The collections element type. (In turn, the result streams element type.) * @return The created {@link FailableStream}. */ public static FailableStream stream(final Collection collection) { return new FailableStream<>(collection.stream()); } /** * Converts the given stream into a {@link FailableStream}. The {@link FailableStream} consists of the same * elements, than the input stream. However, failable lambdas, like {@link FailablePredicate}, * {@link FailableFunction}, and {@link FailableConsumer} may be applied, rather than {@link Predicate}, * {@link Function}, {@link Consumer}, etc. * * @param stream The stream, which is being converted into a {@link FailableStream}. * @param The streams element type. * @return The created {@link FailableStream}. */ public static FailableStream stream(final Stream stream) { return new FailableStream<>(stream); } /** * Tests a predicate and rethrows any exception as a {@link RuntimeException}. * * @param predicate the predicate to test * @param object1 the first input to test by {@code predicate} * @param object2 the second input to test by {@code predicate} * @param the type of the first argument the predicate tests * @param the type of the second argument the predicate tests * @param the type of checked exception the predicate may throw * @return the boolean value returned by the predicate */ public static boolean test(final FailableBiPredicate predicate, final T object1, final U object2) { return getAsBoolean(() -> predicate.test(object1, object2)); } /** * Tests a predicate and rethrows any exception as a {@link RuntimeException}. * * @param predicate the predicate to test * @param object the input to test by {@code predicate} * @param the type of argument the predicate tests * @param the type of checked exception the predicate may throw * @return the boolean value returned by the predicate */ public static boolean test(final FailablePredicate predicate, final T object) { return getAsBoolean(() -> predicate.test(object)); } /** * A simple try-with-resources implementation, that can be used, if your objects do not implement the * {@link AutoCloseable} interface. The method executes the {@code action}. The method guarantees, that all * the {@code resources} are being executed, in the given order, afterwards, and regardless of success, or failure. * If either the original action, or any of the resource action fails, then the first failure (AKA * {@link Throwable} is rethrown. Example use: * *
     * final FileInputStream fis = new FileInputStream("my.file");
     * Functions.tryWithResources(useInputStream(fis), null, () -> fis.close());
     * 
* * @param action The action to execute. This object will always be invoked. * @param errorHandler An optional error handler, which will be invoked finally, if any error occurred. The error * handler will receive the first error, AKA {@link Throwable}. * @param resources The resource actions to execute. All resource actions will be invoked, in the given * order. A resource action is an instance of {@link FailableRunnable}, which will be executed. * @see #tryWithResources(FailableRunnable, FailableRunnable...) */ @SafeVarargs public static void tryWithResources(final FailableRunnable action, final FailableConsumer errorHandler, final FailableRunnable... resources) { final FailableConsumer actualErrorHandler; if (errorHandler == null) { actualErrorHandler = Failable::rethrow; } else { actualErrorHandler = errorHandler; } if (resources != null) { for (final FailableRunnable failableRunnable : resources) { Objects.requireNonNull(failableRunnable, "runnable"); } } Throwable th = null; try { action.run(); } catch (final Throwable t) { th = t; } if (resources != null) { for (final FailableRunnable runnable : resources) { try { runnable.run(); } catch (final Throwable t) { if (th == null) { th = t; } } } } if (th != null) { try { actualErrorHandler.accept(th); } catch (final Throwable t) { throw rethrow(t); } } } /** * A simple try-with-resources implementation, that can be used, if your objects do not implement the * {@link AutoCloseable} interface. The method executes the {@code action}. The method guarantees, that all * the {@code resources} are being executed, in the given order, afterwards, and regardless of success, or failure. * If either the original action, or any of the resource action fails, then the first failure (AKA * {@link Throwable} is rethrown. Example use: * *
     * final FileInputStream fis = new FileInputStream("my.file");
     * Functions.tryWithResources(useInputStream(fis), () -> fis.close());
     * 
* * @param action The action to execute. This object will always be invoked. * @param resources The resource actions to execute. All resource actions will be invoked, in the given * order. A resource action is an instance of {@link FailableRunnable}, which will be executed. * @see #tryWithResources(FailableRunnable, FailableConsumer, FailableRunnable...) */ @SafeVarargs public static void tryWithResources(final FailableRunnable action, final FailableRunnable... resources) { tryWithResources(action, null, resources); } private Failable() { // empty } }