instantiate optinal java 8

In Java 8, the Optional class is a container class that is used to represent the presence or absence of a value. It is used to avoid null checks and to provide a more concise and readable way of dealing with nullable values.

To instantiate an Optional object, you can use one of the following methods:

• empty(): creates an empty Optional object.
• of(T value): creates an Optional object that contains the specified value. If the value is null, a NullPointerException is thrown.
• ofNullable(T value): creates an Optional object that contains the specified value, or an empty Optional object if the value is null.

For example:

// empty Optional
Optional<String> empty = Optional.empty();

// Optional containing a non-null value
Optional<String> nonNull = Optional.of("Hello");

// Optional containing a null value
Optional<String> nullable = Optional.ofNullable(null);

You can use the isPresent() method to check if an Optional object contains a value, and the get() method to retrieve the value. For example:

Optional<String> opt = Optional.of("Hello");
if (opt.isPresent()) {
  String value = opt.get();
  System.out.println(value);  // prints "Hello"
}

The Optional class also provides methods for manipulating and transforming Optional objects, such as map(), flatMap(), and filter().

For more information on the Optional class in Java 8, you can refer to the Java documentation.