How to specify a particular Garbage Collector in JVM (manually or by default)?

In JVM, the choice of garbage collector is set through command line parameters when launching the application. For example:

• -XX:+UseSerialGC — use Serial Garbage Collector.
• -XX:+UseParallelGC — Parallel Garbage Collector (default in some versions).
• -XX:+UseConcMarkSweepGC — CMS (Concurrent Mark Sweep).
• -XX:+UseG1GC — G1 Garbage Collector (often the default in modern JVM versions).
• -XX:+UseZGC — Z Garbage Collector (starting from Java 11).
• -XX:+UseShenandoahGC — Shenandoah (in some builds).

Example of launching with G1 GC:

java -XX:+UseG1GC -jar myapp.jar

If the parameter is not specified, JVM chooses the default garbage collector, which depends on the JVM version and platform.