Is it possible to return the same value in the hashCode() method for all objects, and is this a correct approach?

It is technically possible to return the same value from the hashCode() method for all objects, but this is highly inefficient and not a correct approach.

hashCode() is used for quick distribution of objects into buckets in hash tables (for example, HashMap). If all objects have the same hashCode, they will all go into one bucket, and the performance of operations will degrade to linear.

A correct hashCode should:

• Be deterministic and consistent with equals.
• Distribute objects evenly across the range of values if possible.

Example of a correct hashCode for a class with two fields:

@Override
public int hashCode() {
    return Objects.hash(field1, field2);
}