Explain the differences between Soft Reference and Weak Reference in the context of memory management in Java.

Soft Reference and Weak Reference are types of references in Java that help manage memory by allowing the garbage collector to delete objects under certain conditions.

• Soft Reference: An object referenced by a soft reference will only be garbage collected if the system is low on memory. This is useful for implementing caches where it is desirable to keep objects longer but not hinder garbage collection when necessary.

• Weak Reference: An object referenced by a weak reference can be garbage collected in the next pass if there are no strong references to it, regardless of the memory state. Used, for example, for data structures that should not prevent garbage collection.

Example usage:

import java.lang.ref.*;

public class ReferenceExample {
    public static void main(String[] args) {
        Object strong = new Object();
        SoftReference<Object> soft = new SoftReference<>(strong);
        WeakReference<Object> weak = new WeakReference<>(strong);

        strong = null; // now the object is only accessible via soft and weak references

        System.gc(); // attempt to invoke garbage collector

        System.out.println("Soft reference: " + soft.get()); // most likely the object is retained
        System.out.println("Weak reference: " + weak.get()); // most likely null
    }
}

Thus, soft references hold objects longer than weak references, which is important for cache management and memory optimization.