What is user-defined method in Java?

In Java, there are two types of methods:

The predefined core objects are Array , Boolean , Date , Function , Math , Number , RegExp , and String .

You can write user-defined functions in Java to provide functionality that is not available in Oracle CQL or Oracle CQL built-in functions . You can create a user-defined function that returns an aggregate value or a single (non-aggregate) value.

main(): It is a default signature which is predefined in the JVM . It is called by JVM to execute a program line by line and end the execution after completion of this method.

Predefined Classes in Java. The library of predefined class in Java is called Java class library or application programming interface (API) . In Java, classes are organized into groups called packages. Each package has a specific name such as java.