Handler (linkki Utilities 2.3.10 API)

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
```
@FunctionalInterface
public interface Handler
```
A functional interface to proceed any operation. May be used to provide click handler or any other runnable action.
Handlers can be composed using the andThen(Handler) method.

Field Summary

Fields
Modifier and Type Field Description

static Handler NOP_HANDLER
A handler that does nothing.

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`default Handler`	`andThen(Handler after)`	Returns a composed handler that first executes this handler's `apply()` method and then the `apply()` method of the given handler.
`void`	`apply()`	Called when the handler should be applied.
`default Handler`	`compose(Handler before)`	Returns a composed handler that first applies the `before` handler, and then applies this handler.

- Field Detail
  - NOP_HANDLER
```
static final Handler NOP_HANDLER
```
    A handler that does nothing.
- Method Detail
  - apply
```
void apply()
```
    Called when the handler should be applied.
  - andThen
```
default Handler andThen(Handler after)
```
    Returns a composed handler that first executes this handler's apply() method and then the apply() method of the given handler.
    
    See Also:
    
    compose(Handler)
  - compose
```
default Handler compose(Handler before)
```
    Returns a composed handler that first applies the before handler, and then applies this handler. If evaluation of either handler throws an exception, it is relayed to the caller of the composed handler.
    
    Parameters:
    
    before - the handler to apply before this handler is applied
    
    Returns:
    
    a composed handler that first applies the before handler and then applies this handler
    
    Throws:
    
    NullPointerException - if before is null
    
    See Also:
    
    andThen(Handler)