How to Create an Interface Definition in Java

An interface definition specifies one or more methods by signature (method return type, name, and arguments). The interface does not contain implementation logic for the methods with the exception of any methods marked as default. Therefore, the actual coding of a method can be deferred until a Java program is written to implement an interface and specify method logic for the non-default methods listed in the interface. To create an interface definition in Java, follow these three steps.

  1. Open your text editor and type in the following Java statements:
    Java Source for Interface Definition
    The interface defines three methods for displaying a name and optionally a job title. One method is a default method that contains implementation logic. The remaining two methods do not include implementation logic.
  2. Save your file as
  3. Open a command prompt and navigate to the directory containing your Java program. Then type in the command to compile the source and hit Enter.
    Compile Source for Interface Definition
    The interface is now ready to be implemented by a Java program.
Author: Stephen Withrow

Stephen has over 30 years of experience in training, development, and consulting in a variety of technology areas including Python, Java, C, C++, XML, JavaScript, Tomcat, JBoss, Oracle, and DB2. His background includes design and implementation of business solutions on client/server, Web, and enterprise platforms. Stephen has a degree in Computer Science and Physics from Florida State University.

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