Object & Wrapper - Day 6

Question 1

Object class

Answer 1

Implicit super class of all classes.

Commonly used methods of object class: equals(), hashCode(), toString()

Question 2

Equals method

Answer 2

.equals() compares objects to check for equality

Needs overrideing in the class for it to work for different requirements.

Question 3

hashCode()

Answer 3

Uses object’s data to generate hash value (32 bit integer)

If two objects are equal, hashCode() must produce the same int value for the objects

^ NOT ALWAYS EQUAL IF HASHCODE IS THE SAME

uses formula to generate integer

Equals and hashcode must be overridden together

Question 4

toString()

Answer 4

Returns a textual representation of an object

Question 5

Wrapper class

Answer 5

Convert data types into objects in Java programming.

Boolean, Character, Integer, Long, Float and Double classes

Help represent the primitive data types as objects.

Belong to java.lang package