EventExpression (Apama API Documentation 10.15.3.4)

java.lang.Object
- com.apama.jmon.EventExpression

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

PreparedEventExpression
```
public class EventExpression
extends java.lang.Object
implements java.io.Serializable
```
Instances of this class are declared to represent an "Event Expression" as defined in the Apama reference manual "The JMON Application Framework".

An example expression is:
```
    NewsItem("ACME", *):news -> StockTick("ACME", *)
 
```
In this example the matching NewsItem event is tagged as 'news'. This means that the NewsItem event that caused the match will be available to the MatchListener from the fired MatchEvent by calling evt.getMatchingEvent("news");

When the expression is matched, all registered listeners will be informed. An object implementing the MatchListener interface may be registered by calling the addMatchListener method, and deregistered by calling the removeMatchListener method.
See Also:

Serialized Form

Constructor Summary

Constructors
Constructor Description

EventExpression(java.lang.String eventExpressionString)
Constructor to create a new instance with the given immutable expression string.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`addMatchListener(MatchListener listenerToAdd)`	Add a listener to be notified when the match occurs for this event expression.
`java.lang.String`	`getEventExpressionString()`	Get the String value of the EventExpression.
`void`	`removeAllMatchListeners()`	Remove all previously registered match listeners.
`void`	`removeMatchListener(MatchListener listenerToRemove)`	Remove a match listener that was previously registered.
`java.lang.String`	`toString()`

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - EventExpression
```
public EventExpression(java.lang.String eventExpressionString)
```
    Constructor to create a new instance with the given immutable expression string.
    
    Parameters:
    
    eventExpressionString - The event expression to be used.
- Method Detail
  - getEventExpressionString
```
public java.lang.String getEventExpressionString()
```
    Get the String value of the EventExpression.
    
    Returns:
    
    value of the EventExpression
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
    
    See Also:
    
    getEventExpressionString()
  - addMatchListener
```
public void addMatchListener(MatchListener listenerToAdd)
```
    Add a listener to be notified when the match occurs for this event expression.
    
    Parameters:
    
    listenerToAdd - an object implementing the MatchListener interface to be notified when matches occur for this expression.
  - removeMatchListener
```
public void removeMatchListener(MatchListener listenerToRemove)
```
    Remove a match listener that was previously registered.
    
    Parameters:
    
    listenerToRemove - an object implementing the MatchListener interface to be removed from the notification list for this expression.
  - removeAllMatchListeners
```
public void removeAllMatchListeners()
```
    Remove all previously registered match listeners.