Get topic info

Topic info returns the following values for a topic. Queries do not change the state of the topic or require network consensus. The information is returned from a single node processing the query.

Topic Info Response:

Field

Description

Topic ID

The ID of the topic

Admin Key

Access control for update/delete of the topic. Null if there is no key.

Submit Key

Access control for ConsensusService.submitMessage. Null if there is no key.

Sequence Number

Current sequence number (starting at 1 for the first submitMessage) of messages on the topic.

Running Hash

SHA-384 running hash

Expiration Time

Effective consensus timestamp at (and after) which submitMessage calls will no longer succeed on the topic and the topic will expire and be marked as deleted.

Topic Memo

Short publicly visible memo about the topic. No guarantee of uniqueness.

Auto Renew Period

The lifetime of the topic and the amount of time to extend the topic's lifetime by

Auto Renew Account

Null if there is no autoRenewAccount.

Ledger ID

The ID of the network the response came from. See HIP-198.

Query Signing Requirements

  • The client operator private key is required to sign the query request

Query Fees

  • Please see the transaction and query fees table for the base transaction fee

  • Please use the Hedera fee estimator to estimate your query fee cost

MethodTypeRequirement

setTopicId(<topicId>)

TopicId

Required

<TopicInfo>.adminKey

Optional

<TopicInfo>.submitKey

Optional

<TopicInfo>.topicId

Optional

<TopicInfo>.sequenceNumber

long

Optional

<TopicInfo>.runningHash

ByteString

Optional

<TopicInfo>.memo

String

Optional

<TopicInfo>.ledgerId

LedgerId

Optional

<TopicInfo>.expirationTime

Instant

Optional

<TopicInfo>.autoRenewAccount

Optional

<TopicInfo>.autoRenewPeriod

Instant

Optional

//Create the account info query
TopicInfoQuery query = new TopicInfoQuery()
    .setTopicId(newTopicId);

//Submit the query to a Hedera network
TopicInfo info = query.execute(client);

//Print the account key to the console
System.out.println(info);

//v2.0.0
TopicInfo{
     topicId=0.0.102736, 
     topicMemo=, 
     runningHash=[ 
          0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,            0. 0, 0,0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0
     ], 
     sequenceNumber=0, 
     expirationTime=2021-02-09T03:17:07.258292001Z, 
     adminKey=null, 
     submitKey=null, 
     autoRenewPeriod=PT2160H, 
     autoRenewAccountId=null
}

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