Can you list the types of references used in JVM and explain their features?

The JVM uses the following types of references, which affect garbage collection and object lifetime:

• Strong Reference — a regular reference to an object. As long as a strong reference exists, the object will not be collected by the garbage collector.

• Soft Reference — an object accessible through a soft reference, and the garbage collector will only remove it when memory is low. Used for caching.

• Weak Reference — an object can be collected by the garbage collector on the next pass, even if weak references exist. Used for references that should not prevent garbage collection.

• Phantom Reference — used to track when an object is ready to be collected but has not yet been removed. Allows for additional actions after the object is collected.

Each type of reference allows flexible management of object lifetimes and memory optimization in JVM applications.