Singleton (Weld SPIs for container integration 3.1.SP4 API)

```
public interface Singleton<T>
```
Holds a reference to an application singleton. This singleton is used internally by Weld to store various application scoped objects. This allows Weld to operate as a shared library. In a shared mode, the same instance of Weld implementation is used by all the applications in a server environment. In the exclusive mode, each application loads a separate copy of Weld implementation at the application level. Alternative implementations of Singleton can be used as required

Author:

Sanjeeb.Sahoo@Sun.COM, Pete Muir

See Also:

SingletonProvider

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`clear(String id)`	Clear the singleton
`T`	`get(String id)`	Access the singleton
`boolean`	`isSet(String id)`	Check if the singleton is set
`void`	`set(String id, T object)`	Store a singleton

- Method Detail
  - get
```
T get(String id)
```
    Access the singleton
    
    Parameters:
    
    id - singleton identifier
    
    Returns:
    
    a singleton object
    
    Throws:
    
    IllegalStateException - if the singleton is not set
  - isSet
```
boolean isSet(String id)
```
    Check if the singleton is set
    
    Parameters:
    
    id - singleton identifier
    
    Returns:
    
    true if the singleton is set
  - set
```
void set(String id,
         T object)
```
    Store a singleton
    
    Parameters:
    
    id - singleton identifier
    
    object - the object to store
  - clear
```
void clear(String id)
```
    Clear the singleton
    
    Parameters:
    
    id - singleton identifier