Package org.apache.commons.lang3.function

Class MethodInvokers

java.lang.Object
org.apache.commons.lang3.function.MethodInvokers
public final class MethodInvokers extends Object
Converts Method objects to lambdas.

More specifically, produces instances of single-method interfaces which redirect calls to methods; see asInterfaceInstance(Class, Method).

Calling supplier methods with no arguments

If the interface's single-method defines no arguments, use asFunction(Method) and then apply the function passing in the object to receive the method call.

For example to invoke String.length(): 


 final Method method = String.class.getMethod("length");
 final Function<String, Integer> function = MethodInvokers.asFunction(method);
 assertEquals(3, function.apply("ABC"));

Calling function methods with one argument

If the interface's single-method defines one argument, use asBiFunction(Method) and then apply the function passing in the object to receive the method call. The second argument to the function is the only argument to the method.

For example to invoke String.charAt(int): 


 final Method method = String.class.getMethod("charAt", int.class);
 final BiFunction<String, Integer, Character> function = MethodInvokers.asBiFunction(method);
 assertEquals('C', function.apply("ABC", 2));
Since:
3.13.0

  • Method Details

    • asBiConsumer

      public static <T, U> BiConsumer<T,U> asBiConsumer(Method method)
      Produces a BiConsumer for a given consumer Method. For example, a classic setter method (as opposed to a fluent setter). You call the BiConsumer with two arguments: (1) the object receiving the method call, and (2) the method argument.
      Type Parameters:
      T - the type of the first argument to the operation: The type containing the Method.
      U - the type of the second argument to the operation: The type of the method argument.
      Parameters:
      method - the method to invoke.
      Returns:
      a correctly-typed wrapper for the given target.

    • asBiFunction

      public static <T, U, R> BiFunction<T,U,R> asBiFunction(Method method)
      Produces a BiFunction for a given a function Method. You call the BiFunction with two arguments: (1) the object receiving the method call, and (2) the method argument. The BiFunction return type must match the method's return type.

      For example to invoke String.charAt(int): 

      
 final Method method = String.class.getMethod("charAt", int.class);
 final BiFunction<String, Integer, Character> function = MethodInvokers.asBiFunction(method);
 assertEquals('C', function.apply("ABC", 2));
      Type Parameters:
      T - the type of the first argument to the function: The type containing the method.
      U - the type of the second argument to the function: the method argument type.
      R - the type of the result of the function: The method return type.
      Parameters:
      method - the method to invoke.
      Returns:
      a correctly-typed wrapper for the given target.

    • asFailableBiConsumer

      public static <T, U> FailableBiConsumer<T,U,Throwable> asFailableBiConsumer(Method method)
      Produces a FailableBiConsumer for a given consumer Method. For example, a classic setter method (as opposed to a fluent setter). You call the FailableBiConsumer with two arguments: (1) the object receiving the method call, and (2) the method argument.
      Type Parameters:
      T - the type of the first argument to the operation: The type containing the Method.
      U - the type of the second argument to the operation: The type of the method argument.
      Parameters:
      method - the method to invoke.
      Returns:
      a correctly-typed wrapper for the given target.

    • asFailableBiFunction

      public static <T, U, R> FailableBiFunction<T,U,R,Throwable> asFailableBiFunction(Method method)
      Produces a FailableBiFunction for a given a function Method. You call the FailableBiFunction with two arguments: (1) the object receiving the method call, and (2) the method argument. The BiFunction return type must match the method's return type.
      Type Parameters:
      T - the type of the first argument to the function: The type containing the method.
      U - the type of the second argument to the function: the method argument type.
      R - the type of the result of the function: The method return type.
      Parameters:
      method - the method to invoke.
      Returns:
      a correctly-typed wrapper for the given target.

    • asFailableFunction

      public static <T, R> FailableFunction<T,R,Throwable> asFailableFunction(Method method)
      Produces a FailableFunction for a given a supplier Method. You call the Function with one argument: the object receiving the method call. The FailableFunction return type must match the method's return type.
      Type Parameters:
      T - the type of the first argument to the function: The type containing the method.
      R - the type of the result of the function: The method return type.
      Parameters:
      method - the method to invoke.
      Returns:
      a correctly-typed wrapper for the given target.

    • asFailableSupplier

      public static <R> FailableSupplier<R,Throwable> asFailableSupplier(Method method)
      Produces a FailableSupplier for a given a supplier Method. The FailableSupplier return type must match the method's return type.

      Only works with static methods.

      Type Parameters:
      R - The Method return type.
      Parameters:
      method - the method to invoke.
      Returns:
      a correctly-typed wrapper for the given target.

    • asFunction

      public static <T, R> Function<T,R> asFunction(Method method)
      Produces a Function for a given a supplier Method. You call the Function with one argument: the object receiving the method call. The Function return type must match the method's return type.

      For example to invoke String.length(): 

      
 final Method method = String.class.getMethod("length");
 final Function<String, Integer> function = MethodInvokers.asFunction(method);
 assertEquals(3, function.apply("ABC"));
      Type Parameters:
      T - the type of the first argument to the function: The type containing the method.
      R - the type of the result of the function: The method return type.
      Parameters:
      method - the method to invoke.
      Returns:
      a correctly-typed wrapper for the given target.

    • asInterfaceInstance

      public static <T> T asInterfaceInstance(Class<T> interfaceClass, Method method)
      Produces an instance of the given single-method interface which redirects its calls to the given method.

      For the definition of "single-method", see MethodHandleProxies.asInterfaceInstance(Class, MethodHandle).

      Type Parameters:
      T - The interface type.
      Parameters:
      interfaceClass - a class object representing T.
      method - the method to invoke.
      Returns:
      a correctly-typed wrapper for the given target.
      See Also:

    • asSupplier

      public static <R> Supplier<R> asSupplier(Method method)
      Produces a Supplier for a given a supplier Method. The Supplier return type must match the method's return type.

      Only works with static methods.

      Type Parameters:
      R - The Method return type.
      Parameters:
      method - the method to invoke.
      Returns:
      a correctly-typed wrapper for the given target.