JAVA programming.

Consider a program which can evaluate strings of DNA code. DNA code is a String containing only the letters "C", "T", "G" or "A. Write a method countPattern, that will take in a DNA sequence dna of any length as well as a pattern pattern, and return an int counting the number of times that pattern appears in the dna String. An example, given the dna: "ACACTGACGT" and the pattern: "AC" countPattern(dna, pattern) would return 3