Outline of the Java programming language

The following outline is provided as an overview of and topical guide to Java:

Java is a general-purpose, concurrent, object-oriented, class-based, strong, and statically typed programming language that is compiled to Java bytecode for execution on a Java virtual machine (JVM), which allows "write once, run anywhere" programming. Java was designed by James Gosling and a team at Sun Microsystems in the early 1990s and was a core component of Sun's Java platform.

What type of language is Java?

• Programming language – artificial language designed to communicate instructions to a machine, particularly a computer.
• Object-oriented programming – built primarily around objects and classes.
• Class-based programming – types and code are organized into classes.
• Compiled – source code is compiled to an intermediate form (Java bytecode).
• Interpreted – bytecode is executed by a Java virtual machine, which typically performs Just-in-time compilation.
• General-purpose programming language – designed for a wide variety of application domains.
• Static type checking – type checking is performed at compile-time.
• Strongly typed – enforces strict type rules at compile time.
• Concurrent – built-in support for multithreading and concurrency utilities.

History of Java

• Oak – early name for a new programming language started at Sun Microsystems
• Acquisition of Sun Microsystems by Oracle Corporation in 2010, along with the Java programming language and APIs.
• Oracle litigation against Google's Android OS for using Java APIs from Oracle. See also: Comparison of Java and Android API
• Java 25 – latest major release published September 16, 2025

General Java concepts

See also: and Java syntax

<div style="column-count:3; column-gap:3em;">

• Annotations
• Class loaders
• Concurrency
• Constructors
• Fields
• Garbage collection
• Generics
• Interface (Java)
• Java virtual machine
• Java bytecode
• Java Class Library, standard library
• Java Development Kit
• Java Runtime Environment
• Javadoc
• Java package
• Java Platform Module System
• Lambda expressions
• Methods
• Reflection
• Write once run anywhere

</div>

Issues and limitations

• Abstraction from hardware – students miss low-level cost models
• Array limits – capped size and no true multidimensional arrays
• Checked exceptions – criticized as verbose and largely abandoned by other languages
• Floating-point limits – incomplete IEEE 754 support
• Generics via type erasure – limits expressiveness and caused unsoundness bugs
• Java performance – early implementations were slow compared to C/C++
• Primitive vs. object divide – forces code duplication in libraries
• Serialization – widely seen as a serious security risk
• Lack of tuples – requires awkward workarounds or third-party libraries
• Licensing and governance controversies – Sun Microsystems acquisition by Oracle and subsequent litigation
• No operator overloading – makes math-heavy code less readable
• Potential sources of security vulnerabilities in Java applications
• Project Valhalla (missing value types) – inefficiency due to everything being objects
• Security vulnerabilities – repeated sandbox escapes and exploit waves
• Unsigned integer types – problematic for cryptography and C interop
• Weak parallelism – monitors criticized as insecure and unreliable

Java platform and editions

• Java SE – Java Platform Standard Edition
• Jakarta EE (formerly Java EE) – Enterprise Edition APIs and runtime for multi-tiered server applications
• JavaFX
• Java ME – Micro Edition for constrained devices and embedded systems

Java toolchain

• List of Java software and tools
• List of Java frameworks
• List of Java libraries
• List of Java compilers
• Comparison of Java virtual machines and List of Java virtual machines
• List of JVM languages
• List of application servers for Java
• List of unit testing frameworks for Java
• Comparison of IDEs for Java

Notable projects using Java

• Android (operating system)
• Apache Hadoop
• Apache Tomcat
• Eclipse IDE
• Elasticsearch
• IntelliJ IDEA
• Jenkins
• Minecraft (video game), Java Edition
• NetBeans

Java open-source development communities

• Apache Software Foundation – Apache Commons, Apache Maven, Apache Tomcat, Apache Kafka
• Eclipse Foundation – Adoptium, Eclipse IDE, Jakarta EE, Eclipse Jetty, Eclipse Vert.x
• OpenJDK community – Java Platform, Standard Edition
• Oracle – GraalVM (Community Edition), JavaFX (OpenJFX)
• Red Hat / JBoss – Hibernate, Drools, Quarkus

Example source code

Java publications

Books about Java

• Bruce Eckel – Thinking in Java
• James Gosling – The Java Programming Language
• Joshua Bloch – Effective Java
• Kathy Sierra – Head First Java
• Herbert Schildt – Java: The Complete Reference, Java: A Beginner's Guide, Java 2 Programmer's Reference

Java programmers

• Arthur van Hoff
• Bill Joy
• Craig L. Russell
• Doug Lea
• Gilad Bracha
• Guy L. Steele Jr.
• James Gosling
• Joshua Bloch
• Martin Odersky
• Urs Hölzle

Java dialects and related languages

• Clojure – JVM Lisp dialect
• Groovy
• JRuby – JVM Ruby implementation
• Jython – JVM Python implementation
• Kotlin – JVM JetBrains language
• Scala – JVM language combining object-oriented and functional paradigms

See also

• Java Community Process
• Java version history
• Outline of computer programming
• Outline of software
• Outline of software engineering
• List of Kotlin software and tools
• List of programmers

Outlines of other programming languages

• Outline of the C programming language
• Outline of the C sharp programming language
• Outline of the C++ programming language
• Outline of the JavaScript programming language
• Outline of the Perl programming language
• Outline of the Python programming language
• Outline of the Rust programming language

External links

• Oracle – Java
• OpenJDK – reference implementation and community
• Java.com – runtime download and general info

References