Author Archives: Stanislav_Panteleev

🚀 Difference Between this.getClass() == that.getClass() and that instanceof MyClass in equals() When implementing equals(), checking the type of that is important to avoid class mismatches.There are two common ways to check if an object is of the same type: … Continue reading →

🚀 Can equals(Object that) Be Implemented as return this.hashCode() == that.hashCode();? No, 2 objects, having same hashcode (collissions) maybe not equal acually. No, this is an incorrect implementation of equals().It violates the contract of equals() and leads to incorrect behavior … Continue reading →

🚀 Can Different References to the Same Object (ref0 == ref1) Have ref0.equals(ref1) == false? No, this cannot happen if equals() is correctly implemented. If two references point to the same object in memory (ref0 == ref1), then equals() must … Continue reading →

🚀 Can Different Objects (ref0 != ref1) Have ref0.equals(ref1) == true? Yes! Different objects (with different memory addresses) can still be considered equal if equals() is overridden to compare their contents rather than their references.

No, the points will not be correctly handled in a HashSet. The issue is that hashCode() only uses x, while equals() compares both x and y.This violates the contract between equals() and hashCode().

🚀 Can Different Objects Have the Same hashCode()? Yes! Different objects can have the same hashCode(), and this is called a hash collision. The hashCode() method does not guarantee uniqueness—instead, it tries to distribute objects efficiently in hash-based collections like … Continue reading →

🚀 Guidelines for Choosing Fields in hashCode() Calculation When overriding hashCode(), selecting the right fields is crucial to ensure correctness, efficiency, and consistency in Java collections like HashMap, HashSet, and HashTable.

🚀 Rules for Overriding hashCode() in Java When overriding hashCode(), follow these rules to ensure correctness, efficiency, and compliance with Java collections like HashMap, HashSet, and HashTable.

🚀 Purpose of the hashCode() Method in Java The hashCode() method returns an integer (hash code) for an object. This hash code is used by hash-based collections like HashMap, HashSet, and HashTable to efficiently store and retrieve objects.

Implementation of hashCode() and equals() in Object Class The Object class in Java provides default implementations of hashCode() and equals(), which are inherited by all Java classes unless explicitly overridden.