java

Run class file

$ java [ClassName]

$ java -jar [application.jar]

$ java -cp [path/to/classes] [ClassName]

$ java -Xmx[512m] -jar [app.jar]

$ java -D[property=value] [ClassName]

$ java -version

$ java [Source.java]

java [options] class [args...]
java [options] -jar jarfile [args...]

java launches Java applications by loading and executing compiled bytecode in the Java Virtual Machine (JVM). It can run individual class files, JAR archives, or since Java 11, single source files directly.
The runtime handles memory management through garbage collection, threading, and platform abstraction. JVM options control heap size, garbage collector behavior, and system properties. The classpath mechanism locates dependencies, while the module path (Java 9+) provides stronger encapsulation.

CLASS

Main class to execute.

Execute JAR file.

Class path for dependencies.

Maximum heap size.

Initial heap size.

Set system property.

Show version information.

Display help information.

JAVA_HOME

Environment variable pointing to the JDK installation directory.

Environment variable specifying default class search paths.

Environment variable for default JVM options applied to all Java invocations.

Environment variable for JVM options (vendor-specific, overrides JAVATOOLOPTIONS).

Requires JRE/JDK. Version compatibility matters. Memory settings may need tuning.

Java was created by James Gosling at Sun Microsystems in 1995. It's now maintained by Oracle and the OpenJDK community.

javac(1), jar(1), jps(1), jstack(1)