Java8 - OptionalLong Class Example

#java.util.OptionalLong

OptionalLong class is introduced in java8 along with OptionalInt and OptionalDouble. This is an optional container for long values that may or may not contain empty or nonempty values. if long value is present,isPresent() method returns true. getAsLong() method returns long value.OptionalLong is a primitive long version of Optional class whereas Optional is an Optional class for Long Object. It is defined java.util package since java8 version

#Creation Empty OptionalLong Instance

empty() method creates OptionalLong instance. There is no object presented with this. isPresent() method returns false, false meaning absence of values

OptionalLong emptyOptionalLong= OptionalLong.empty();
System.out.println(emptyOptionalLong.isPresent()); // returns false

#Create OptionalLong Instance with no null values

OptionalLong.of(long) method creates an OptionalLong instance with the long value presented in it.

 OptionalLong valueOptionalLong = OptionalLong.of(51);
System.out.println(valueOptionalLong.isPresent()); // returns true

#ifPresentOrElse() method example

ifPresentOrElse method checks, if the value exists, apply consumer on the value, else empty value.

 OptionalLong optionalLongvalue = OptionalLong.of(5);
optionalLongvalue.ifPresentOrElse((value) ->{
System.out.println("data exists: " + value);
}, () -> {
System.out.println("Not exists");
});

 data exist: 5

#getAsLong() method example

getAsLong() method returns value if present, else throws NoSuchElementException

OptionalLong optionalLong = OptionalLong.of(20);
System.out.println(optionalLong.getAsLong());

output is

20

#OptionalLong Example

This is an example of usage of Lambda expression with OptionalLong and utility methods like empty(),of(int),ifPresentOrElse()

OptionalLong emptyOptionalLong = OptionalLong.empty();
OptionalLong valueOptionalLong= OptionalLong.of(58);
valueOptionalLong.ifPresentOrElse((value) -> {
System.out.println("data exists: " + value);
}, () -> {
System.out.println("Not exists");
});
emptyOptionalLong.ifPresentOrElse((value) -> {
System.out.println("data exists: " + value);
}, () -> {
System.out.println("Not exists");
});

data exists: 58
Not exists

#How to Convert OptionalLong to Long in java8

OptionalLong.getAsLong() method returns primitive long value. Follow is an example for Convert to a primitive long value

long longValue =0;
OptionalLong optionalLong = OptionalLong.of(4);
if(optionalLong.isPresent()) {
longValue=optionalLong.getAsLong();
}
System.out.println(longValue); // output 4

Output is

4
Not exists

#Convert long to OptionalLong in java8

OptionalLong.of() method used to create OptionalLong with non empty long value. Syntax: public static OptionalLong of(long value) This takes long Value as input and returns OptionalLong object.

long longValue = 121l;
OptionalLong optionalLong = OptionalLong.of(longValue);
System.out.println(optionalLong.isPresent()); // returns true
System.out.println(optionalLong.getAsLong()); // returns 121

true
121

#Difference between OptionalLong and Optional Long in java8?

Optional<Long>.get() returns Long Object OptionalLong.getAsLong() method returns long primitive value IntStream and OptionalLong objects of long value have a posiblility of nullpointerexception Optional<Long> and Stream<Long> for long value acts as extra wrapper to avoid null exceptions.

#java8 OptionalInt Methods

OptionalInt provides many utilities for handling available and not available.