Many a programmer has been bitten by NullPointerException. While occurring less in Java than C or C++, it may still occur. Now, Java has the idea of an Optional field. An Optional field may or may not contain a value. You can test whether there is a value present or not rather than the awkward null tests that exist.
We can run through several aspects of Optional by using the following code snippet:
import java.util.Optional;
public class MyOptional {
public static void main() {
MyOptional program = new MyOptional();
Integer value1 = null;
Integer value2 = 123;
//.ofNullable allows null
Optional<Integer> a = Optional.ofNullable(value1);
//.of does not allow null
Optional<Integer> b = Optional.of(value2);
System.out.println(program.sum(a,b));
}
public Integer sum(Optional<Integer> first, Optional<Integer>
second) {
System.out.println...