Package org.apache.commons.lang3.function

Class Failable

  • public class Failable
extends Object
    This class provides utility functions, and classes for working with the 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 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 Consumer<O> with a 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

    • Method Detail

      • accept

        public static <T,​U,​E extends Throwable> void accept​(FailableBiConsumer<T,​U,​E> consumer,
                                                                T object1,
                                                                U object2)
        Consumes a consumer and rethrows any exception as a RuntimeException.
        Type Parameters:
        T - the type of the first argument the consumer accepts
        U - the type of the second argument the consumer accepts
        E - the type of checked exception the consumer may throw
        Parameters:
        consumer - the consumer to consume
        object1 - the first object to consume by consumer
        object2 - the second object to consume by consumer

      • accept

        public static <T,​E extends Throwable> void accept​(FailableConsumer<T,​E> consumer,
                                                        T object)
        Consumes a consumer and rethrows any exception as a RuntimeException.
        Type Parameters:
        T - the type the consumer accepts
        E - the type of checked exception the consumer may throw
        Parameters:
        consumer - the consumer to consume
        object - the object to consume by consumer

      • accept

        public static <E extends Throwable> void accept​(FailableDoubleConsumer<E> consumer,
                                                double value)
        Consumes a consumer and rethrows any exception as a RuntimeException.
        Type Parameters:
        E - the type of checked exception the consumer may throw
        Parameters:
        consumer - the consumer to consume
        value - the value to consume by consumer

      • accept

        public static <E extends Throwable> void accept​(FailableIntConsumer<E> consumer,
                                                int value)
        Consumes a consumer and rethrows any exception as a RuntimeException.
        Type Parameters:
        E - the type of checked exception the consumer may throw
        Parameters:
        consumer - the consumer to consume
        value - the value to consume by consumer

      • accept

        public static <E extends Throwable> void accept​(FailableLongConsumer<E> consumer,
                                                long value)
        Consumes a consumer and rethrows any exception as a RuntimeException.
        Type Parameters:
        E - the type of checked exception the consumer may throw
        Parameters:
        consumer - the consumer to consume
        value - the value to consume by consumer

      • apply

        public static <T,​U,​R,​E extends Throwable> R apply​(FailableBiFunction<T,​U,​R,​E> function,
                                                                    T input1,
                                                                    U input2)
        Applies a function and rethrows any exception as a RuntimeException.
        Type Parameters:
        T - the type of the first argument the function accepts
        U - the type of the second argument the function accepts
        R - the return type of the function
        E - the type of checked exception the function may throw
        Parameters:
        function - the function to apply
        input1 - the first input to apply function on
        input2 - the second input to apply function on
        Returns:
        the value returned from the function

      • apply

        public static <T,​R,​E extends Throwable> R apply​(FailableFunction<T,​R,​E> function,
                                                            T input)
        Applies a function and rethrows any exception as a RuntimeException.
        Type Parameters:
        T - the type of the argument the function accepts
        R - the return type of the function
        E - the type of checked exception the function may throw
        Parameters:
        function - the function to apply
        input - the input to apply function on
        Returns:
        the value returned from the function

      • applyAsDouble

        public static <E extends Throwable> double applyAsDouble​(FailableDoubleBinaryOperator<E> function,
                                                         double left,
                                                         double right)
        Applies a function and rethrows any exception as a RuntimeException.
        Type Parameters:
        E - the type of checked exception the function may throw
        Parameters:
        function - the function to apply
        left - the first input to apply function on
        right - the second input to apply function on
        Returns:
        the value returned from the function

      • asBiConsumer

        public static <T,​U> BiConsumer<T,​U> asBiConsumer​(FailableBiConsumer<T,​U,​?> consumer)
        Converts the given FailableBiConsumer into a standard BiConsumer.
        Type Parameters:
        T - the type of the first argument of the consumers
        U - the type of the second argument of the consumers
        Parameters:
        consumer - a failable BiConsumer
        Returns:
        a standard BiConsumer

      • asBiFunction

        public static <T,​U,​R> BiFunction<T,​U,​R> asBiFunction​(FailableBiFunction<T,​U,​R,​?> function)
        Converts the given FailableBiFunction into a standard BiFunction.
        Type Parameters:
        T - the type of the first argument of the input of the functions
        U - the type of the second argument of the input of the functions
        R - the type of the output of the functions
        Parameters:
        function - a FailableBiFunction
        Returns:
        a standard BiFunction

      • asBiPredicate

        public static <T,​U> BiPredicate<T,​U> asBiPredicate​(FailableBiPredicate<T,​U,​?> predicate)
        Converts the given FailableBiPredicate into a standard BiPredicate.
        Type Parameters:
        T - the type of the first argument used by the predicates
        U - the type of the second argument used by the predicates
        Parameters:
        predicate - a FailableBiPredicate
        Returns:
        a standard BiPredicate

      • asCallable

        public static <V> Callable<V> asCallable​(FailableCallable<V,​?> callable)
        Converts the given FailableCallable into a standard Callable.
        Type Parameters:
        V - the type used by the callables
        Parameters:
        callable - a FailableCallable
        Returns:
        a standard Callable

      • asConsumer

        public static <T> Consumer<T> asConsumer​(FailableConsumer<T,​?> consumer)
        Converts the given FailableConsumer into a standard Consumer.
        Type Parameters:
        T - the type used by the consumers
        Parameters:
        consumer - a FailableConsumer
        Returns:
        a standard Consumer

      • asFunction

        public static <T,​R> Function<T,​R> asFunction​(FailableFunction<T,​R,​?> function)
        Converts the given FailableFunction into a standard Function.
        Type Parameters:
        T - the type of the input of the functions
        R - the type of the output of the functions
        Parameters:
        function - a {code FailableFunction}
        Returns:
        a standard Function

      • asPredicate

        public static <T> Predicate<T> asPredicate​(FailablePredicate<T,​?> predicate)
        Converts the given FailablePredicate into a standard Predicate.
        Type Parameters:
        T - the type used by the predicates
        Parameters:
        predicate - a FailablePredicate
        Returns:
        a standard Predicate

      • asSupplier

        public static <T> Supplier<T> asSupplier​(FailableSupplier<T,​?> supplier)
        Converts the given FailableSupplier into a standard Supplier.
        Type Parameters:
        T - the type supplied by the suppliers
        Parameters:
        supplier - a FailableSupplier
        Returns:
        a standard Supplier

      • call

        public static <V,​E extends Throwable> V call​(FailableCallable<V,​E> callable)
        Calls a callable and rethrows any exception as a RuntimeException.
        Type Parameters:
        V - the return type of the callable
        E - the type of checked exception the callable may throw
        Parameters:
        callable - the callable to call
        Returns:
        the value returned from the callable

      • get

        public static <T,​E extends Throwable> T get​(FailableSupplier<T,​E> supplier)
        Invokes a supplier, and returns the result.
        Type Parameters:
        T - The suppliers output type.
        E - The type of checked exception, which the supplier can throw.
        Parameters:
        supplier - The supplier to invoke.
        Returns:
        The object, which has been created by the supplier

      • getAsBoolean

        public static <E extends Throwable> boolean getAsBoolean​(FailableBooleanSupplier<E> supplier)
        Invokes a boolean supplier, and returns the result.
        Type Parameters:
        E - The type of checked exception, which the supplier can throw.
        Parameters:
        supplier - The boolean supplier to invoke.
        Returns:
        The boolean, which has been created by the supplier

      • getAsDouble

        public static <E extends Throwable> double getAsDouble​(FailableDoubleSupplier<E> supplier)
        Invokes a double supplier, and returns the result.
        Type Parameters:
        E - The type of checked exception, which the supplier can throw.
        Parameters:
        supplier - The double supplier to invoke.
        Returns:
        The double, which has been created by the supplier

      • getAsInt

        public static <E extends Throwable> int getAsInt​(FailableIntSupplier<E> supplier)
        Invokes an int supplier, and returns the result.
        Type Parameters:
        E - The type of checked exception, which the supplier can throw.
        Parameters:
        supplier - The int supplier to invoke.
        Returns:
        The int, which has been created by the supplier

      • getAsLong

        public static <E extends Throwable> long getAsLong​(FailableLongSupplier<E> supplier)
        Invokes a long supplier, and returns the result.
        Type Parameters:
        E - The type of checked exception, which the supplier can throw.
        Parameters:
        supplier - The long supplier to invoke.
        Returns:
        The long, which has been created by the supplier

      • getAsShort

        public static <E extends Throwable> short getAsShort​(FailableShortSupplier<E> supplier)
        Invokes a short supplier, and returns the result.
        Type Parameters:
        E - The type of checked exception, which the supplier can throw.
        Parameters:
        supplier - The short supplier to invoke.
        Returns:
        The short, which has been created by the supplier

      • rethrow

        public static RuntimeException rethrow​(Throwable throwable)

        Rethrows a Throwable as an unchecked exception. If the argument is already unchecked, namely a RuntimeException or Error then the argument will be rethrown without modification. If the exception is IOException then it will be wrapped into a UncheckedIOException. In every other cases the exception will be wrapped into a 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 return statement from a value returning method.

        Parameters:
        throwable - The throwable to rethrow ossibly wrapped into an unchecked exception
        Returns:
        Never returns anything, this method never terminates normally.

      • run

        public static <E extends Throwable> void run​(FailableRunnable<E> runnable)
        Runs a runnable and rethrows any exception as a RuntimeException.
        Type Parameters:
        E - the type of checked exception the runnable may throw
        Parameters:
        runnable - The runnable to run

      • test

        public static <T,​U,​E extends Throwable> boolean test​(FailableBiPredicate<T,​U,​E> predicate,
                                                                 T object1,
                                                                 U object2)
        Tests a predicate and rethrows any exception as a RuntimeException.
        Type Parameters:
        T - the type of the first argument the predicate tests
        U - the type of the second argument the predicate tests
        E - the type of checked exception the predicate may throw
        Parameters:
        predicate - the predicate to test
        object1 - the first input to test by predicate
        object2 - the second input to test by predicate
        Returns:
        the boolean value returned by the predicate

      • test

        public static <T,​E extends Throwable> boolean test​(FailablePredicate<T,​E> predicate,
                                                         T object)
        Tests a predicate and rethrows any exception as a RuntimeException.
        Type Parameters:
        T - the type of argument the predicate tests
        E - the type of checked exception the predicate may throw
        Parameters:
        predicate - the predicate to test
        object - the input to test by predicate
        Returns:
        the boolean value returned by the predicate

      • tryWithResources

        @SafeVarargs
public static void tryWithResources​(FailableRunnable<? extends Throwable> action,
                                    FailableConsumer<Throwable,​? extends Throwable> errorHandler,
                                    FailableRunnable<? extends Throwable>... resources)
        A simple try-with-resources implementation, that can be used, if your objects do not implement the AutoCloseable interface. The method executes the action. The method guarantees, that all the 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 Throwable is rethrown. Example use: 
         final FileInputStream fis = new FileInputStream("my.file");
 Functions.tryWithResources(useInputStream(fis), null, () -> fis.close());
        Parameters:
        action - The action to execute. This object will always be invoked.
        errorHandler - An optional error handler, which will be invoked finally, if any error occurred. The error handler will receive the first error, AKA Throwable.
        resources - The resource actions to execute. All resource actions will be invoked, in the given order. A resource action is an instance of FailableRunnable, which will be executed.
        See Also:
        tryWithResources(FailableRunnable, FailableRunnable...)

      • tryWithResources

        @SafeVarargs
public static void tryWithResources​(FailableRunnable<? extends Throwable> action,
                                    FailableRunnable<? extends Throwable>... resources)
        A simple try-with-resources implementation, that can be used, if your objects do not implement the AutoCloseable interface. The method executes the action. The method guarantees, that all the 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 Throwable is rethrown. Example use: 
         final FileInputStream fis = new FileInputStream("my.file");
 Functions.tryWithResources(useInputStream(fis), () -> fis.close());
        Parameters:
        action - The action to execute. This object will always be invoked.
        resources - The resource actions to execute. All resource actions will be invoked, in the given order. A resource action is an instance of FailableRunnable, which will be executed.
        See Also:
        tryWithResources(FailableRunnable, FailableConsumer, FailableRunnable...)