Question 2 : If the answer is because they both have same hash code,only then equals will be called, then why its not called for below code. sset.add (obj1); sset.add (obj4); sset.add (obj2); sset.add (obj4); output is : in hash code value is 98 in hash code value is 97 in hash code value is 99 in hash code value is 97. 99 4. A code-only answer is not high quality. While this code may be useful, you can improve it by saying why it works, how it works, when it should be used, and what its limitations are. Please edit your answer to include explanation and link to relevant documentation. – Stephen Ostermiller. What is the proper way to use a .equals method in Java? 2. Providing an alternative to equals()? 0. checking if something is equal to different things java. 2. 1. The hashCode () and equals () Methods. equals (Object otherObject) – verifies the equality of two objects. It’s default implementation simply checks the object references of two objects to verify their equality. By default, two objects are equal if and only if they refer to the same memory location. Most Java classes override this method In Java, it’s particularly important because most of the collections (HashTable, etc.) are based on the equals method. If you put a member of the super class in a hash table as the key and then This is how you would call the .equals () method in order to compare the 2 triangles for equality: tri1.equals (tri2); Apache Common's EqualsBuilder class is useful in its own right. But it is also useful for learning how to write your own equals method. In general, in your equals method, you want to: The Set.equals () method is only used to compare two sets for equality. You can use a Set to get rid of the duplicate entries, but beware: HashSet doesn't use the equals () methods of its containing objects to determine equality. A HashSet carries an internal HashMap with entries and uses equals () as well as the 2 Answers. If the lists may contain null elements, you will need to handle them properly when comparing the elements. One way to handle null elements is to use the Objects.equals (Object a, Object b) method from the java.util.Objects class. This method compares two objects for equality and returns true if both objects are null or if the a The equals () method is the primary method used to compare two objects in Java. When we override the equals () method, we must also override the hashcode () method to ensure that two equal objects have the same hash code. By using the equals () and hashcode () methods, we can compare two objects based on their internal state, rather than their The Integer equals() method simply compares the int value it wraps with the other Integer's int value. Hashcodes don't come into it. Note that the equals() and hashcode aggrement is not strictly required, but it is relied upon by the numerous JDK classes that use an internal Hashtable, eg the various java.util.Hashxxx classes. dS1oVgi.