Java jgrasp the user has to enter DNA details. Help

A gene mutation is a permanent change in the DNA sequence that makes up a gene. Mutations range in size from a single DNA building block (DNA base) to a large segment of a chromosome. Write a program to compare two dna sequences of same length to detect any mutation (change) in them and identify the locations of mutations. Thymine (T), Adenine (A), Cytosine (C), and Guanine (G)