subprojects/groovy-json/src/spec/doc/_streaming-jason-builder.adoc

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= StreamingJsonBuilder

Unlike `JsonBuilder` which creates a data structure in memory, which is handy in those situations where you want to alter the structure programmatically before output,
`StreamingJsonBuilder` directly streams to a writer without any intermediate memory data structure.
If you do not need to modify the structure and want a more memory-efficient approach, use `StreamingJsonBuilder`.

The usage of `StreamingJsonBuilder` is similar to `JsonBuilder`. In order to create this Json string:

[source,groovy]
----
include::../test/json/StreamingJsonBuilderTest.groovy[tags=json_string,indent=0]
----

you use a `StreamingJsonBuilder` like this:

[source,groovy]
----
include::../test/json/StreamingJsonBuilderTest.groovy[tags=streaming_json_builder,indent=0]
----

We use https://github.com/lukas-krecan/JsonUnit[JsonUnit] to check the expected result:

[source,groovy]
----
include::../test/json/StreamingJsonBuilderTest.groovy[tags=json_assert,indent=0]
----

If you need to customize the generated output you can pass a `JsonGenerator` instance when creating a `StreamingJsonBuilder`:

[source,groovy]
----
include::../test/json/StreamingJsonBuilderTest.groovy[tags=streaming_json_builder_generator,indent=0]
----