# \[JAVA\] UDP Library - Regarding the 'multicast address' setting

**URL:** <https://discourse.processing.org/t/java-udp-library-regarding-the-multicast-address-setting/36144>\
**Category:** Libraries\
**Created:** [April 5, 2022, 9:12pm UTC](https://discourse.processing.org/t/java-udp-library-regarding-the-multicast-address-setting/36144 "2022-04-05T21:12:30Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![GWAK](https://avatars.discourse-cdn.com/v4/letter/g/13edae/32.png) [@GWAK](https://discourse.processing.org/u/GWAK)\
**Post date:** [April 5, 2022, 9:12pm UTC](https://discourse.processing.org/t/java-udp-library-regarding-the-multicast-address-setting/36144/1 "2022-04-05T21:12:30Z")

</div>

[JAVA] UDP Library - Regarding the ‘multicast address’ setting

Hello.

It is related to the ‘UDP’ library.  
link : [hypermedia.net : : UDP](http://ubaa.net/shared/processing/udp/udp_class_udp.htm)

1. If you do not use ‘multicast address’,  
1:N communication is not working?

2. for example,  
2-1) Without ‘multicast address’  
2-2) Set like the code below,

```auto
udp = new UDP( this, 12000 );
udp.listen( true );

```

2-3) At this time, can’t I receive data in 1:N?  
(The 1 referred to here is the PC that has set ‘new UDP( this, 12000 )’.)

If anyone knows, please reply.