Lambda expressions
A lambda implements a functional interface without an anonymous class. It does not have its own this.
Related reading: Lambdas and functional programming
Curriculum file: versions3Java8Features.java
JDK 8 · JSR 337 · Long-term support
Java 8
Java SE 8 is JSR 337, released in March 2014. Oracle and other vendors have treated it as a long-term support line. This is the functional release: lambdas, the stream library, Optional, and java.time. The chapters on lambdas and streams teach those topics in depth. This page only says what arrived.
Language
Functional interfaces
java.util.function supplies the common single-method types the new APIs accept, such as Predicate, Function, and Consumer.
Related reading: Lambdas and functional programming
Curriculum file: versions3Java8Features.java
Method references
A method reference points at an existing method or constructor where a functional interface is required.
Related reading: Lambdas and functional programming
Curriculum file: versions3Java8Features.java
Default and static interface methods
An interface can carry a default instance method and a static method. That is how Collection gained stream() without breaking existing classes.
Related reading: Abstraction and interfaces
Curriculum file: versions3Java8Features.java
APIs / Libraries
Stream API
A stream is a pipeline of intermediate operations and one terminal operation. Intermediate work stays lazy until the terminal operation runs.
Related reading: Streams and Optional
Curriculum file: versions3Java8Features.java
Optional
Optional is a return type for a value that may be absent. The stream chapter covers how to use it.
Related reading: Streams and Optional
Curriculum file: versions3Java8Features.java
java.time
The java.time package replaces the mutable java.util.Date and Calendar model for civil dates, times, and instants.
Curriculum file: versions3Java8Features.java
CompletableFuture
A completion stage composes asynchronous work. It is not the virtual-thread API. Virtual threads arrive as a preview in Java 19 and become final in Java 21.
Related reading: Concurrency
JVM / Runtime
Metaspace
Class metadata moves from the fixed PermGen space to Metaspace. This is a JVM change, not a source change.
Related reading: JVM and memory
Tools / Platform
Nashorn
Nashorn is a JavaScript engine that shipped in Java 8. Java 11 deprecates it. Java 15 removes it.
Examples
- versions3Java8Features.javaLambdas, a default method, method references, streams, Optional, and java.time.
Related reading
Historical notes
Java 8 is the baseline many later migrations leave. The Java 11 page lists what changed between these two long-lived releases, without ranking them.
Sources. Release month and JSR 337: Oracle Java SE specifications. Feature set: the Java versions reference and versions3Java8Features.java. Oracle Java SE specifications (leaves JavaMastery)