Garbage collection in Java is the automatic process of finding and deleting objects in memory that are no longer needed by your program. This helps prevent memory leaks and ensures that your application does not run out of memory over time.

You do not need to manually free memory in Java. Instead, the Java Virtual Machine (JVM) tracks which objects are still being used and which can be safely removed. When the JVM detects that an object is unreachable—meaning your code no longer has any references to it—garbage collection will eventually reclaim the memory for reuse.

The main goal of garbage collection is to make memory management easier and safer for you as a developer. By handling memory cleanup behind the scenes, Java lets you focus on writing your application logic without worrying about low-level resource management.

Why Java Needs Garbage Collection

Java uses garbage collection to manage memory automatically. This is important because:

• Manual memory management is error-prone and complex;
• Forgetting to free memory can cause memory leaks, leading to slowdowns or crashes;
• Accidentally freeing memory too early can cause bugs and unpredictable program behavior.

With garbage collection, Java automatically detects and removes objects that are no longer needed. This helps you:

• Focus on writing code, not tracking every object in memory;
• Avoid common memory-related bugs;
• Build stable and efficient applications.

You do not need to explicitly allocate or free memory for most objects. The Java runtime handles it for you, making programming safer and easier.

Memory Leaks in Long-Running Applications

Suppose you are building a server that handles thousands of user requests every hour. Without automatic garbage collection, you would need to manually free memory every time an object is no longer needed. This is error-prone and can easily lead to memory leaks — situations where unused objects remain in memory, eventually causing your application to slow down or crash.

Garbage collection in Java automatically reclaims memory from objects that are no longer referenced. This means you can focus on building features rather than tracking every object’s lifecycle.

Example scenario:

• You develop a Java-based web server that stores user session data in memory.
• When a user logs out, the session object becomes unreachable.
• The garbage collector detects that no code references the session object and frees the memory for reuse.

Without garbage collection, you would have to explicitly find and remove every unused session object. In a complex, multi-threaded application, forgetting to do so could cause your server to run out of memory over time.