Useful Method

• String Class toCharArray() //get char array of a String charAt(int x) //get a char at the specific index length() //string length length //array size substring(int beginIndex) substring(int beginIndex, int endIndex) String.valueOf()/integer to string String.join(CharSequence delimiter, CharSequence... elements) 1.8

• Character Character.isLetterOrDigit(ch) Character.toLowerCase(ch)

• Integer Integer.valueOf()//string to integer

• StringBuffer StringBuffer(str).reverse(); str.replaceAll("[^A-Za-z0-9]", "")

• Arrays Arrays.sort() //sort an array Arrays.toString(char[] a) //convert to string Arrays.copyOf(T[] original, int newLength) Arrays.asList(T[]) System.arraycopy(Object src, int srcPos, Object dest, int destPos, int length)

• Collections Collections.reverse(List)