build-a-java-app-with-cockroachdb.md

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Build a Java App with CockroachDB	Learn how to use CockroachDB from a simple Java application with the jdbc driver.	false	true

Use jdbc Use Hibernate

This tutorial shows you how build a simple Java application with CockroachDB using a PostgreSQL-compatible driver or ORM. We've tested and can recommend the Java jdbc driver and the Hibernate ORM, so those are featured here.

Before You Begin

Make sure you have already installed CockroachDB.

Step 1. Install the Java jdbc driver

Download and set up the Java jdbc driver as described in the official documentation.

{% include app/common-steps.md %}

Step 5. Run the Java code

Now that you have a database and a user, you'll run code to create a table and insert some rows, and then you'll run code to read and update values as an atomic transaction.

Basic Statements

First, use the following code to connect as the maxroach user and execute some basic SQL statements, creating a table, inserting rows, and reading and printing the rows.

You can copy the code or download it directly.

{% include app/BasicSample.java %}

Transaction (with retry logic)

Next, use the following code to again connect as the maxroach user but this time execute a batch of statements as an atomic transaction to transfer funds from one account to another, where all included statements are either committed or aborted.

You can copy the code or download it directly.

{{site.data.alerts.callout_info}}With the default SERIALIZABLE isolation level, CockroachDB may require the client to retry a transaction in case of read/write contention. CockroachDB provides a generic retry function that runs inside a transaction and retries it as needed. You can copy and paste the retry function from here into your code.{{site.data.alerts.end}}

{% include app/TxnSample.java %}

After running the code, use the built-in SQL client to verify that funds were transferred from one account to another:

$ cockroach sql --insecure -e 'SELECT id, balance FROM accounts' --database=bank

+----+---------+
| id | balance |
+----+---------+
|  1 |     900 |
|  2 |     350 |
+----+---------+
(2 rows)

What's Next?

Read more about using the Java jdbc driver.

You might also be interested in using a local cluster to explore the following core CockroachDB features:

• Data Replication
• Fault Tolerance & Recovery
• Automatic Rebalancing