@Pimchaya.Wongrukun please help me with this.
The RIC for all currencies. You can use RIC Search tool to find the RIC that you want. Additionally, you may contact a Data support team to help find the RIC by opening a content-related enquiry via Get Support https://my.refinitiv.com/content/mytr/en/productsupport.html link. Please select "I cannot find content I am looking for" and "Thomson Reuters Elektron Real-Time" Product as picture shows below:
Regarding the implementation. I strongly suggest you follow through EMA Java Tutorial that give you a step by step guide to implement your application with EMA Java to connect and consume data from Elektron.
Other example that can help you is EMA Java Consumer example120__MarketPrice__FieldListWalk example in the API package. It contains a source code that iterates through is incoming Field Data of the requested RIC.
Additional resources to help you study EMA Java and learn how to implement your application: