# Confused about Ray.init() in Java

**URL:** <https://discuss.ray.io/t/confused-about-ray-init-in-java/3547>\
**Category:** Uncategorized\
**Created:** [September 16, 2021, 5:40pm UTC](https://discuss.ray.io/t/confused-about-ray-init-in-java/3547 "2021-09-16T17:40:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![JUAN\_CHEN](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/juan_chen/32/1512_2.png) [@JUAN\_CHEN](https://discuss.ray.io/u/JUAN_CHEN)\
**Post date:** [September 16, 2021, 5:40pm UTC](https://discuss.ray.io/t/confused-about-ray-init-in-java/3547/1 "2021-09-16T17:40:10Z")

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Hi, I am newer in Ray. I have 2 problems which confuse me when I use java language.

1. I looked into Ray.init() in java and finally looked into CoreWorkerProcess::Initialize(options), however I can’t find where to launch the raylet process. I only find it initialize the raylet client.
2. Java api only support non-para function Ray.init(), the parameters have to pass into via -D like -Dray.address. How can I verify these system properties pass into successfully?

Thank anyone for responding me!

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**Author:** ![simon-mo](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/simon-mo/32/9_2.png) [@simon-mo](https://discuss.ray.io/u/simon-mo)\
**Post date:** [September 16, 2021, 11:47pm UTC](https://discuss.ray.io/t/confused-about-ray-init-in-java/3547/2 "2021-09-16T23:47:33Z")

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For Ray.init(), the cluster (including raylet) was started via command line, the final command is [ray/RunManager.java at 12b3b1f7238db655a8ab41530d3709e7e6cfbed8 · ray-project/ray · GitHub](https://github.com/ray-project/ray/blob/12b3b1f7238db655a8ab41530d3709e7e6cfbed8/java/runtime/src/main/java/io/ray/runtime/runner/RunManager.java#L23)

For these configuration are read and parsed in as [ray/RayConfig.java at 12b3b1f7238db655a8ab41530d3709e7e6cfbed8 · ray-project/ray · GitHub](https://github.com/ray-project/ray/blob/12b3b1f7238db655a8ab41530d3709e7e6cfbed8/java/runtime/src/main/java/io/ray/runtime/config/RayConfig.java#L22) and I think you check them via `RayConfig.create()` to view the instance.

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**Author:** ![JUAN\_CHEN](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/juan_chen/32/1512_2.png) [@JUAN\_CHEN](https://discuss.ray.io/u/JUAN_CHEN)\
**Post date:** [September 17, 2021, 6:47pm UTC](https://discuss.ray.io/t/confused-about-ray-init-in-java/3547/3 "2021-09-17T18:47:13Z")

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Thank you @Simon. Your response helps a lot.