How to store string increments as a concatenated String? - string

Question

Scanner input = new Scanner(System.in);
String userInput = input.nextLine();
String letterArray[] = new String[userInput.length()];
for(int i = 0; i < userInput.length(); i++ ){
letterArray[i] = userInput.substring(i, i+1);
}
for(int j = userInput.length()-1; j>=0; j--){
System.out.print(letterArray[j]);
}
I have stored the users input now I want to reverse what they have inputted and store the reversed form as a String.
I have managed to display the String as a superposition of each letter increment which has been stored in an Array, how do I go about storing the reversed form as a String?

Answer 1

If you just want to print it reverse you can do that:
Scanner input = new Scanner(System.in);
String userInput = input.nextLine();
for(int i=1;i<=userInput.length();i++){
System.out.print(userInput.charAt(userInput.length()-i));
}
Other than that if you wanto to turn string to array you can use simpler methods like: String[] letterArray = userInput .split("");
If you want to store it as an array or as a new string you can do this:
Scanner input = new Scanner(System.in);
String userInput = input.nextLine();
Char[] characters=new Char[userInput.length];
for(int i=1;i<=userInput.length();i++){
characters[i-1]=userInput.charAt(userInput.length()-i);
System.out.print(characters[i-1]);
}
String newString=new String(characters);
There are many possibilities.

Answer 2

You can obtain the reversed java.lang.String in different ways.
The safest would be using the java.lang.StringBuilder.reverse() method:
System.out.println(new java.lang.StringBuilder("abc").reverse().toString());
If you want to learn how to iterate the characters and add them in the way you want, you can use the StringBuilder, appending the characters one by one with the java.lang.StringBuilder.append(char c) method.
WARNING: uncommon case ahead.
There is an special case where you cannot alter the order of the characters, not even reverse them.
It refers to the surrogate pairs of UTF-16. Those are pairs of individual characters in the Java java.lang.String (say chars c1 and c2) but actually refer to a single unicode character.
If you build an string reversing the chars in that pair (c2 then c1), you would be building an incorrect string.
Update: I have just seen that the documentation of the StringBuider.reverse() method describes this about surrogate pairs explicitly. Read it here: http://docs.oracle.com/javase/7/docs/api/java/lang/StringBuilder.html#reverse()