In this Java 101 tutorial, I’ve explained how interfaces differ from classes, and showed you how to declare, implement, and extend interfaces in your Java programs.

Java’s interface language feature confuses many Java newbies. ... Suppose two superclasses declare a read/write variable with the same name but different types and/or initial values.

The other types of variables in Java are: byte – stores whole numbers from -128 to 127; short – stores numbers from -32,768 to 32,767; int – stores whole numbers from -2,147,483,648 to ...