Explain weak and strong references.

A weak reference is a reference that does not prevent the referenced object from being garbage collected. If no strong references to the object exist, the garbage collector can remove the object from memory, even if weak references are still pointing to it.

Use Cases

• Caches: When you want to hold an object in memory temporarily but do not want to prevent it from being collected if memory is low.
• Event Listeners: When you want an object to reference another object without keeping it alive just because of the reference.
• Observer patterns: In scenarios where observers (listeners) are weakly held to avoid keeping objects alive longer than necessary.

Issue It Resolves

• Helps manage memory efficiency by allowing objects to be collected when no longer in active use, especially in complex systems like caching or event handling.
• Avoids memory leaks when objects should not be held in memory unnecessarily.

A strong reference is the most common type of reference. When you create an object in a program, it is typically referenced strongly by default. If an object has a strong reference pointing to it, the object will not be collected by the garbage collector (GC), as the GC considers it to still be in use.

Use Cases

• Standard object management.
• When you want to ensure that an object remains in memory as long as it is needed.

Issue It Resolves

• Strong references prevent an object from being deallocated, which is critical for maintaining the lifecycle of objects that are actively in use.