Is it possible for a HashMap to work like a list even if keys have different hashCodes()?

In theory, no, because HashMap uses hashCode() and equals() to determine the location and uniqueness of keys. If different keys have different hash codes, they will be placed in different buckets or different nodes within the same bucket, which does not correspond to the behavior of a list where elements are indexed sequentially.

HashMap may appear to work like a list when all keys are added in a certain order and there are no hash code conflicts (collisions), or when a linked list is used in buckets in case of many collisions. However, this is not guaranteed behavior and depends on the implementation of HashMap and the distribution of hash codes.

To achieve list-like behavior with the ability for associative access by key, but without strict guarantees of insertion order and performance, ArrayList or LinkedList can be used, with LinkedHashMap being a good choice. It preserves insertion order or access order (depending on the constructor), and provides Map operations.

Example of using LinkedHashMap:

import java.util.LinkedHashMap;
import java.util.Map;

// Create a LinkedHashMap that preserves insertion order
Map<String, Integer> map = new LinkedHashMap<>();

// Add elements
map.put("one", 1);
map.put("two", 2);
map.put("three", 3);

// Iteration over elements retains insertion order
for (Map.Entry<String, Integer> entry : map.entrySet()) {
    System.out.println("Key: " + entry.getKey() + ", Value: " + entry.getValue());
}

In this case, even with different hashCode() keys, iteration will occur in insertion order, resembling list behavior.

Thus, a classic HashMap cannot become a list due to its internal hash-based structure. LinkedHashMap is closer to this behavior, preserving order, but still remains an implementation of Map.