I need help with the following question please in JAVA code.

1. Hash code is used to encode general keys into integers. One approach of creating a hash code is to use Java's hashCode() method. The hashCode() method is implemented in the Object class and therefore each class in Java inherits it. The hash code provides a numeric representation of an object (this is somewhat similar to the toString method that gives a text representation of an object).

1. Write a program to show the hash code of the following.

Integer 2018,

String 2018,

StringBuffer 2018,

ArrayList with first element is Integer 2018.

2. Verify that different objects might have the same hashcode. For example, show the hashcode for the strings Aa and BB.