1/*2 * NumOccur.java3 *4 * Computer Science S-225 *6 * A class that contains a recursive method for determining the7 * number of times that a character appears in a string.8 *9 * The main method includes two examples of using this method.10 *11 * You can also test this method by entering12 * NumOccur.numOccur(ch, str) -- where ch is replaced by a char13 * and str is replaced by a string -- from the Interactions Pane.14 */15 16public class NumOccur {17 /*18 * numOccur - a recursive method that returns the number of times 19 * that the character ch occurs in the String str.20 */21 public static int numOccur(char ch, String str) {22 // base case23 if (str == null || str.equals("")) {24 return 0;25 }26 27 // recursive case28 int numOccurInRest = numOccur(ch, str.substring(1));29 if (ch == str.charAt(0)) {30 return 1 + numOccurInRest;31 } else {32 return numOccurInRest;33 }34 }35 36 public static void main(String[] args) {37 System.out.println("numOccur('s', \"Mississippi\") = " +38 numOccur('s', "Mississippi"));39 System.out.println("numOccur('e', \"Mississippi\") = " +40 numOccur('e', "Mississippi")); 41 }42}