With this example we are going to demonstrate how to reverse a String with a StringTokenizer. The StringTokenizer is used to break a String into tokens. In short, to reverse a String with a StringTokenizer you should:
- Get a new StringTokenizer for a specified String, using the
StringTokenizer(String str)constructor. - Create a new empty String, that will be the reversed String.
- Invoke
hasMoreTokens()andnextToken()API methods of StringTokenizer to get the tokens of this String and add each one of them to the beggining of the reversed String, using a space character between them. After taking all the tokens of the Strings, the reversed String will contain all the tokens of the initial one, in the reversed order.
Let’s take a look at the code snippet that follows:
package com.javacodegeeks.snippets.core;
import java.util.StringTokenizer;
public class ReverseStringWithStringTokenizer {
public static void main(String[] args) {
String s = "Java Code Geeks - Java Examples";
StringTokenizer st = new StringTokenizer(s);
String sReversed = "";
while (st.hasMoreTokens()) {
sReversed = st.nextToken() + " " + sReversed;
}
System.out.println("Original string is : " + s);
System.out.println("Reversed string is : " + sReversed);
}
}
Output:
Original string is : Java Code Geeks - Java Examples
Reversed string is : Examples Java - Geeks Code Java
This was an example of how to reverse a String with a StringTokenizer in Java.
String sReversed = st.nextToken();while
(st.hasMoreTokens()) {
sReversed = st.nextToken() +
" "
+ sReversed;
}
//would be more effective and avoids space at the end of reversed string.