In what cases does data update occur in the Stream flow?

In Java, a stream represents a sequence of elements on which operations can be performed.

Data updates in a stream occur when the stream is created from a mutable data source, and this source changes during the execution of stream operations. However, the stream itself is immutable and lazy — operations on it do not modify the original data but create new streams.

Data updates in a stream happen in the following cases:

• If the data source (e.g., a collection) is modified after the stream is created, and the stream has not yet been processed, then during a terminal operation, the stream will 'see' the current data.
• If the stream is built from a generator or another dynamic source, data can be updated with each call.

It is important to remember that streams are not intended for modifying the original data but for processing and transforming it. To update data, operations like map, filter, and collect are typically used, which create new collections or values.