Java 10 major language and API improvements

2024-07-19 2 min read Martin

Java ⑩ has been released in March 2018.

The following content is summarizing the most important changes to the Java API and the Java language introduced with Java ⑩.

For a more complete overview follow the links in the following sections referring to the official Oracle release documents.

Java 10 Language improvements

The following describes selected improvements of the Java language. See the Java 10 release notes.

Local Variable Type Inference

var is not a keyword but a reserved type identifier. The type is inferred from the initializer.

See https://openjdk.java.net/projects/amber/LVTIstyle.html which discusses when var should be used and when best avoided.

var

var source = List.of("one", "two");
var copy = List.copyOf(source);

Java 10 API improvements

The following describes selected improvements of the Java API. See the Java 10 release notes.

Collectors

To Unmodifiable List

List<String> copy=source
    .stream()
    .collect(Collectors.toUnmodifiableList());

With Collectors.toUnmodifiableList() we can now convert a list into an immutable list.

To Unmodifiable Set

Set<String> copy=source
    .stream()
    .collect(Collectors.toUnmodifiableSet());

With Collectors.toUnmodifiableSet() we can now convert a set into an immutable set.

To Unmodifiable Map

Map<Integer,String> copy=source
    .entrySet()
    .stream()
    .collect(Collectors
        .toUnmodifiableMap(Map.Entry::getKey, Map.Entry::getValue));

With Collectors.toUnmodifiableMap() we can now convert a map into an immutable map.

Map

Copy Of

var source = Map
    .of(1, "one", 2, "two");
var copy = Map.copyOf(source);

With Map.copyOf we can now create an immutable copy of a list.

Optional

Or Else Throw

Optional.of("OK")
    .orElseThrow();

A argumentless method Optional.orElseThrow() that throws a NoSuchElementException has been added.

Set

Copy Of

var source = Set.of("one", "two");
var copy = Set.copyOf(source);

With Set.copyOf we can now create an immutable copy of a list.

List

Copy Of

var source = List.of("one", "two");
var copy = List.copyOf(source);

With List.copyOf we can now create an immutable copy of a list.

JVM Runtime

Container Awareness

A JVM running in a container is now aware of this and CPU and memory information is now reported as allocated by the container.

See https://www.docker.com/blog/improved-docker-container-integration-with-java-10/.