Java - HashCode & Equals

HashCode & Equals :

• Every object have access equals method.
• package : java.lang.object
• Default implementation of equals, just simply compares memory address of the object.
• If you override equals you must override hashcode as well. Otherwise it is the violation of general contract for Object-hashcode will occur.
• Hashcode common algorithm is to start with some arbitrary number and repeatedly multiply with another
• For Example,

int prime = 31;

int result = 1;

result = prime * result + ( ( firstname==null ) ? 0 : firstName.hashcode());

result = prime * result + ( ( lastName == null ) ? 0 : lastName.hashcode());

return result;