diff --git a/src/solution/test.java b/src/solution/test.java
new file mode 100644
index 0000000..d8b5b3b
--- /dev/null
+++ b/src/solution/test.java
@@ -0,0 +1,47 @@
+package solution;
+
+
+public class test {
+    public static void main(String[] args) {
+        String s = "abcabcbb";
+        Character a = 'a';
+//        int length = lengthOfLongestSubstring(s);
+//        System.out.println(isInString(a,));
+
+    }
+
+    public static int lengthOfLongestSubstring(String s) {
+        StringBuilder longestString = new StringBuilder();
+        StringBuilder lastMaxString = new StringBuilder();
+        if (s != null){
+            for (int i = 0; i < s.length(); i++) {
+                char temp = s.charAt(i);
+                if (i == 0){
+                    continue;
+                }
+                Character prChar = s.charAt(i-1);
+                if (prChar != temp){
+                    boolean in = isInString(temp,longestString);
+                    if (!in){
+                        lastMaxString.append(temp);
+                    }
+
+                }
+            }
+            return longestString.length();
+        }
+        return 0;
+    }
+
+    public static boolean isInString(Character a,StringBuilder b){
+        if (b != null) {
+            for (int i = 0; i < b.length(); i++) {
+                Character temp = b.charAt(i);
+                if (temp == a) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+}