org.cactoos.scalar

Class Retry<T>

java.lang.Object

org.cactoos.scalar.Retry<T>

Type Parameters:

T - Type of output

All Implemented Interfaces:

Scalar<T>

public final class Retry<T>
extends Object
implements Scalar<T>

Func that will try a few times before throwing an exception.

 new RetryScalar<>(
     () -> {
         if (new SecureRandom().nextDouble() > 0.3d) {
             throw new IllegalArgumentException("May happen");
         }
         return 0;
     },
     5
 ).value() // will try to run 5 times before throwing an exception
 

There is no thread-safety guarantee.

This class implements Scalar, which throws a checked Exception. This may not be convenient in many cases. To make it more convenient and get rid of the checked exception you can use the Unchecked decorator. Or you may use IoChecked to wrap it in an IOException.

Since:

0.9

Constructor Summary

Constructors

Constructor and Description
Retry(Scalar<T> scalar) Ctor.
Retry(Scalar<T> scalar, Duration wait) Ctor.
Retry(Scalar<T> scalar, Func<Integer,Boolean> exit) Ctor.
Retry(Scalar<T> scalar, Func<Integer,Boolean> exit, Duration wait) Ctor.
Retry(Scalar<T> scalar, int attempts) Ctor.
Retry(Scalar<T> scalar, int attempts, Duration wait) Ctor.

Method Summary

Modifier and Type	Method and Description
T	value() Convert it to the value.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Retry

public Retry(Scalar<T> scalar)

Ctor.

Parameters:

scalar - Scalar original

Retry

public Retry(Scalar<T> scalar,
             Duration wait)

Ctor.

Parameters:

scalar - Scalar original

wait - The Duration to wait between attempts

Retry

public Retry(Scalar<T> scalar,
             int attempts)

Ctor.

Parameters:

scalar - Scalar original

attempts - Maximum number of attempts

Retry

public Retry(Scalar<T> scalar,
             int attempts,
             Duration wait)

Ctor.

Parameters:

scalar - Scalar original

attempts - Maximum number of attempts

wait - The Duration to wait between attempts

Retry

public Retry(Scalar<T> scalar,
             Func<Integer,Boolean> exit)

Ctor.

Parameters:

scalar - Func original

exit - Exit condition, returns TRUE if there is no reason to try

Retry

public Retry(Scalar<T> scalar,
             Func<Integer,Boolean> exit,
             Duration wait)

Ctor.

Parameters:

scalar - Func original

exit - Exit condition, returns TRUE if there is no reason to try

wait - The Duration to wait between attempts

Method Detail

value

public T value()
        throws Exception

Description copied from interface: Scalar

Convert it to the value.

Specified by:

value in interface Scalar<T>

Returns:

The value

Throws:

Exception - If fails