Prerequisites

You need access and appropriate permissions to complete the code example.

Java Development Kit 8 or later (see Java Downloads)
Eclipse IDE for Java Developers (get a recent version from http://www.eclipse.org/downloads/eclipse-packages/). This example walks you through the steps of building the project with the Eclipse IDE but you can you use your preferred IDE to build the Java client.
To run the tool from the command line: Apache Maven (see https://maven.apache.org/index.html)
Access to a Developer Edition org
To create a Developer Edition org, go to developer.salesforce.com/signup and follow the instructions for signing up for a Developer Edition organization.
The API Enabled permission must be enabled for your Developer Edition org. This permission is enabled by default, but an admin might have changed it.
The Streaming API permission must be enabled in Setup, in the User Interface page. This permission is enabled by default, but an admin might have been changed it.
The logged-in user must have Read permission on the PushTopic standard object to receive notifications.
The logged-in user must have Create permission on the PushTopic standard object to create and manage PushTopic records.
The logged-in user must have Author Apex permission to create a PushTopic from the Developer Console.

Streaming API Developer Guide