In this Java tutorial, we will learn to reverse the characters of a string using the recursion and StringBuilder.reverse() methods. You may like to read about reversing the words in a sentence also.
1. Reverse using Recursion
To reverse all the characters of the string, we can write a recursive function that will perform the following actions –
- Take the first character and append it to the last of the string
- Perform the above operation, recursively, until the string ends
public class ReverseString {
public static void main(String[] args) {
String blogName = "How To Do In Java";
String reverseString = reverseString(blogName);
Assertions.assertEquals("avaJ nI oD oT woH", reverseString);
}
public static String reverseString(String string) {
if (string.isEmpty()) {
return string;
}
return reverseString(string.substring(1)) + string.charAt(0);
}
}
2. Reverse using StringBuilder.reverse()
We can also reverse a string easily, using a StringBuilder.reverse() method. The reverse() method causes the characters of String to be replaced by the reverse of the sequence.
String blogName = "How To Do In Java";
String reverseString = new StringBuilder(blogName).reverse().toString();
Assertions.assertEquals("avaJ nI oD oT woH", reverseString);
Happy Learning !!
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