What is a built in class?

Built in functions in java are methods that are present in different API of JDK . For example cos(double a), exp(double a) etc are built in function of java present in java. lang. Math class.

Built in functions in java are methods that are present in different API of JDK . For example cos(double a), exp(double a) etc are built in function of java present in java. lang. Math class.

There are 5,000 or so classes built-in to Java, and programmers have written hundreds of thousands if not millions of their own.

There are 5,000 or so classes built-in to Java, and programmers have written hundreds of thousands if not millions of their own.