A Java class file is a file containing Java bytecode and having .class extension that can be executed by JVM. A Java class file is created by a Java compiler from .java files as a result of successful compilation.
As we know that a single Java programming language source file (or we can say .java file) may contain one class or more than one class. So if a .java file has more than one class then each class will compile into a separate class files.
For Example: Save this below code as Test.java on your system.
Related Article : https://www.geeksforgeeks.org/java-class-file/