Negate (Storm 2.7.1 API)

java.lang.Object
- org.apache.storm.trident.operation.builtin.Negate

All Implemented Interfaces:

Serializable, EachOperation, Filter, Operation
```
public class Negate
extends Object
implements Filter
```
A `Filter` implementation that inverts another delegate `Filter`.
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:

Serialized Form

Constructor Summary

Constructors
Constructor Description

Negate(Filter delegate)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`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.

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

- Constructor Detail
  - Negate
```
public Negate(Filter delegate)
```
- Method Detail
  - isKeep
```
public boolean isKeep(TridentTuple tuple)
```
    Description copied from interface: Filter
    
    Determines if a tuple should be filtered out of a stream.
    
    Specified by:
    
    isKeep in interface Filter
    
    Parameters:
    
    tuple - the tuple being evaluated
    
    Returns:
    
    `false` to drop the tuple, `true` to keep the tuple
  - prepare
```
public void prepare(Map<String,Object> conf,
                    TridentOperationContext context)
```
    Description copied from interface: Operation
    
    Called when the `Operation` is first initialized.
    
    Specified by:
    
    prepare in interface Operation
    
    Parameters:
    
    conf - the Storm configuration map
    
    context - 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:
    
    TridentOperationContext
  - cleanup
```
public void cleanup()
```
    Description copied from interface: Operation
    
    When running in local mode, called when the local cluster is being shut down.
    
    Specified by:
    
    cleanup in interface Operation