Garbage collection in Java is the way Java programs actually manage their memory. The main purpose of garbage collection is to identify and reclaim memory with items no longer accessed or used by the application This helps prevent memory leaks and provides efficient memory management without explicit programmer intervention. 

Mechanism of Garbage Collection in Java

Identifying Unreachable Objects
The Java garbage collector searches outside the root objects (such as from main() methods, strings, etc.) and identifies objects that cannot be retrieved. If a reference chain cannot be retrieved from this node, it is considered garbage.

Reclaiming Memory
Once identified as waste, the recovered residuals of these materials are accepted and are available for future distribution of materials.

Types of Garbage Collectors in Java

Java offers several types of garbage collectors, each suitable for different situations based on application needs, memory size, and performance considerations. The choice of garbage collection can significantly affect the performance and responsiveness of Java applications.

Serial Garbage Collector (-XX:+UseSerialGC)

Description- Provides a single-threaded garbage collection method, suitable for small or low memory tasks.

Usage- Usually used for client-side applications or applications with small amounts of data.

Parallel Collection Collector (-XX:+Use ParallelGC)

Description- Uses multiple threads for garbage collection, making it suitable for multi-core systems and high performance applications.

Usage- Typically used for applications that require high performance and handle medium to large data sets.

Concurrent Mark Sweep (CMS) Garbage Collector (-XX:+UseConcMarkSweepGC)

Description- Uses multiple threads for most of its actions, but also tries to reduce latency by performing most of the garbage collection tasks concurrently with the application threads

Usage- Suitable for simple applications, communication, or breathable applications.

G1 (Garbage First) Garbage Collector (-XX:+UseG1GC)

Description- Designed for low latency, server-style garbage collection. It divides the garbage into zones and collects garbage in small parts of the garbage (known as "garbage-first zones).

Usage- Recommended for large heaps (multi-GB heaps), where it is important to minimize processing time, such as in server applications.

Z Garbage Collector (ZGC) (-XX:+UseZGC)

Description- A low latency garbage collector designed to handle very large heaps (up to 16TB) with latency not exceeding 10ms.

Usage- Suitable for large applications and applications that require low latency and consistently high throughput, such as financial services and big data applications.

Choosing the Right Garbage Collector

Heap Size- Large heaps benefit from collectors that can handle large memory regions efficiently (e.g., G1, ZGC).

Latency Requirements- Applications that require low latency should consider a collector optimized for low latency (e.g., CMS, G1, ZGC).

Throughput- Applications with high transaction rates or applications requiring high throughput can benefit from aggregators optimized for throughput (e.g. parallel GC).

Also, Read: How to handle exceptions using try, catch, finally, throw, and throws in Java?