Add Java solution for 125

Java solution for Valid Palindrome, checked that it passed Leetcode judge

Author: acmoroca

125-Valid-Palindrome.java

@@ -0,0 +1,9 @@
+public boolean isPalindrome(String s) {
+        StringBuilder content = new StringBuilder();
+        for(int i = 0; i < s.length(); i++) 
+            if(Character.isLetterOrDigit(s.charAt(i)))
+                content.append(s.charAt(i));
+        content = new StringBuilder(content.toString().replace(" ", "").toLowerCase());
+        String value = content.toString();
+        return value.equals(content.reverse().toString());
+    }