Class Negate
- All Implemented Interfaces:
Serializable
,EachOperation
,Filter
,Operation
The `Negate.isKeep()` method simply returns the opposite of the delegate's `isKeep()` method:
```java public boolean isKeep(TridentTuple tuple) { return !this.delegate.isKeep(tuple); } ```
The `Negate` filter is useful for dividing a Stream in two based on some boolean condition.
Suppose we had a Stream named `userStream` containing information about users, and a custom `Filter` implementation, `RegisteredUserFilter` that filtered out unregistered users. We could divide the `userStream` Stream into two separate Streams -- one for registered users, and one for unregistered users -- by doing the following:
```java Stream userStream = ...
Filter registeredFilter = new ResisteredUserFilter(); Filter unregisteredFilter = new Negate(registeredFilter);
Stream registeredUserStream = userStream.each(userStream.getOutputFields(), registeredFilter); Stream unregisteredUserStream = userStream.each(userStream.getOutputFields(), unregisteredFilter); ```
- See Also:
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionvoid
cleanup()
When running in local mode, called when the local cluster is being shut down.boolean
isKeep
(TridentTuple tuple) Determines if a tuple should be filtered out of a stream.void
prepare
(Map<String, Object> conf, TridentOperationContext context) Called when the `Operation` is first initialized.
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Constructor Details
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Negate
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Method Details
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isKeep
Description copied from interface:Filter
Determines if a tuple should be filtered out of a stream. -
prepare
Description copied from interface:Operation
Called when the `Operation` is first initialized.- Specified by:
prepare
in interfaceOperation
- Parameters:
conf
- the Storm configuration mapcontext
- the operation context which provides information such as the number of partitions in the stream, and the current partition index. It also provides methods for registering operation-specific metrics.- See Also:
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cleanup
public void cleanup()Description copied from interface:Operation
When running in local mode, called when the local cluster is being shut down.
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