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Java 17 1Z0-829 Glossary: Key Terms

Oracle Java 1Z0-829 glossary of Java 17 language, flow, objects, collections, streams, and concurrency terms.

Keep this glossary nearby when Java 17 terms start to blur together. The exam punishes fuzzy vocabulary because fuzzy vocabulary usually hides fuzzy reasoning.

Assertion

Java correctness check intended for internal assumptions, not normal user-facing business flow.

Autoboxing

Automatic conversion between a primitive and its wrapper type such as int and Integer.

Encounter Order

The order elements are seen while iterating or streaming, which can affect results for ordered operations.

Functional Interface

An interface with one abstract method, suitable for lambdas and method references.

Generic Bound

A restriction such as extends or super that limits what types are legal in a generic context.

Immutable

Unable to change after construction. Strings and many record use cases are common examples.

Method Reference

Lambda shorthand such as String::length or System.out::println.

Module Readability

JPMS concept that determines whether one module can depend on another.

Optional

Container type representing presence or absence of a value without using null directly as the signal.

Pattern Matching

Java syntax that combines a type test with variable binding, such as pattern-aware instanceof.

PECS

Short rule for wildcard direction: producer extends, consumer super.

Record

Concise Java type for modeling data with generated constructor, accessors, equals, hashCode, and toString.

Resource Bundle

Localization mechanism that stores locale-specific text resources.

Sealed Type

Class or interface that explicitly restricts which other types may extend or implement it.

Stream Pipeline

A chain of stream operations that stays lazy until a terminal operation runs.

Terminal Operation

The stream operation that actually triggers evaluation, such as collect, count, or forEach.

Try-with-Resources

Statement form that closes declared resources automatically, typically in reverse declaration order.

Unmodifiable Collection

Collection view or factory result that rejects structural modification attempts.

Wildcard

Generic placeholder type such as ?, ? extends T, or ? super T.

Yield

Keyword used to return a value from a block-style switch expression arm.

Revised on Sunday, May 10, 2026