Method isSubstring

java/Chapter 1/Question1_8/Question.java:4–10

(String big, String small)

public class Question {
	public static boolean isSubstring(String big, String small) {
		if (big.indexOf(small) >= 0) {
			return true;
		} else {
			return false;
		}
	}
	
	public static boolean isRotation(String s1, String s2) {
	    int len = s1.length();