两个字符串中最大相同子串

public class StringTest3 {

	/**
	 * 两个字符串中最大相同的子串
	 */
	public static void main(String[] args) {
		String s1="qwertabcyuiop";
		String s2="fgabchjkl";
		String s=maxCommonSubstring(s1,s2);
		System.out.println(s);
	}

	private static String maxCommonSubstring(String s1, String s2) {
		String ss;
		String bs;
		String sub;
		if (s1.length()>s2.length()) {
			ss=s2;
			bs=s1;
		}
		else {
			ss=s1;
			bs=s2;
		}
		for (int i =0; i <ss.length(); i++) {
			for (int j = 0; j < i+1; j++) {
				sub=ss.substring(j, ss.length()+j-i);
				if(bs.contains(sub)){
					return sub;
				}
			}
		}
		return null;
	}

}