You should explore the contents of this project. It demonstrates a CDK app with an instance of a stack (%name.PascalCased%Stack) which contains an Amazon SQS queue that is subscribed to an Amazon SNS topic.

The cdk.json file tells the CDK Toolkit how to execute your app.

It is a Maven based project, so you can open this project with any Maven compatible Java IDE to build and run tests.

Useful commands

mvn package compile and run tests
cdk ls list all stacks in the app
cdk synth emits the synthesized CloudFormation template
cdk deploy deploy this stack to your default AWS account/region
cdk diff compare deployed stack with current state
cdk docs open CDK documentation

Enjoy!