Provider (net.markenwerk:commons-interfaces 2.1.1 API)

Type Parameters:

Product - The type of the values to be provided.
```
public interface Provider<Product>
```
A Provider provides values of the corresponding product type.
Implementers may provide a new instance of the product each time provide() is called, but aren't requiered to do so. An instance of the product that has already been returned once, may be returned again for any or all following calls.
It is therefore not recommended to use Provides for products that are stateful unless the internal state of a values doesn't change the value. It is for example okay to use String as the product type, although instances are stateful (String instances store their hash value after it has been calculated for the first time and are therefore technically stateful), but it is not okay to use Iterator as the product type, because every call to Iterator.next() actually changes the Iterator instance.
Providers are intended to be used in situatuation, where a mechanism to retreive a value is more desirable than having the value from the start. Theese are usually, but not necessarily, situations where the following two conditions are met.
- It is not certein that the value will be used.
- It is likeley that it is a costly operation to create the value.
The second condition may only be true for the first call to provide() since Providers are allowed to cache and reuse the value.
Since:

1.0.0

Author:

Torsten Krause (tk at markenwerk dot net)

See Also:

Producer

- Method Summary
  
  All Methods Instance Methods Abstract Methods
  Modifier and Type Method and Description
  
  Product provide()
  Provides a product, This may be a costly operation.

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`Product`	`provide()` Provides a product, This may be a costly operation.

- Method Detail
  - provide
```
Product provide()
         throws ProvisioningException
```
    Provides a product, This may be a costly operation.
    Implementers may provide a new instance of the product each time this method is called, but aren't requiered to do so. An instance of the product that has already been returned once, may be returned again in any or all following calls.
    It lies in the responsibility of the caller, to handle unwanted null-values by replacing them with a sensible default value or throwing a NullPointerException.
    Implementers should catch any exception and wrap them in a ProvisioningException.
    
    Returns:
    
    The provided product.
    
    Throws:
    
    ProvisioningException - If the provisioning of the product failed.

Interface Provider<Product>

Method Summary

Method Detail

provide