Java获取两个字符串中最大相同子串

@Test
public void testGetSomeStr() {
    String a = "sffioafihellosdfvasdf";
    String b = "sfhellodesdfs";
    String c = getSomeStr(a, b);
    System.out.println(c); //=> hello
}
public String getSomeStr(String str1, String str2) {
    // 获取两个字符串中的最大值
    String maxstr = str1;
    String minstr = str2;
    if (str2.length() > str1.length()) {
        maxstr = str2;
        minstr = str1;
    }
    // 先确定循环多少轮
    int lunCount = minstr.length();
    for (int i = 0; i < lunCount; i++) {
        // 确定每轮循环多少次
        for (int x = 0, y = lunCount - i; y <= lunCount; x++, y++) {
            if(maxstr.contains(minstr.substring(x,y))){
                return minstr.substring(x,y);
            }
        }
    }
    return null;
}