class Util {
public String reverseOrderOfWords(String input) {
String[] words = input.split(" ");
StringBuilder reverseString = new StringBuilder();
for (int i = words.length - 1; i >= 0; i--) {
reverseString.append(words[i]).append(" ");
}
System.out.println("reverseOrderOfWordsString = " + reverseString);
return reverseString;
}
}Reverse order of words inside string in Java
Upasana | November 21, 2020 | 1 min read | 225 views
In this article, we will reverse the order of words in a given String using Java.
- input
-
This is sample
- output
-
sample is This
Solution
-
Tokenize each word using
String.split()method and create an array of words. -
Loop through words and join them in reverse order.
Java Implementation
Reverse the order of words in a string
Input:
this is sample
Output
sample is this
Another approach using collections
We can use collections to reverse the order of words using the below steps:
-
Split the String into words using white space as separator
-
Reverse the collection consisting of words
-
Join the collections of the words back into a string
Java 8 Program to reverse the order of words in String
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
public class ReverseWords {
public String reverseJava8Style(String input){
List<String> list = Arrays.asList(input.split("[\\s]"));
Collections.reverse(list);
return String.join(" ", list);
}
}
public class ReverseWordsTest {
ReverseWords utils = new ReverseWords();
@Test
public void reverseJava8Style() {
String reverseJava8Style = utils.reverseJava8Style("My Name is Tanishq");
assertThat(reverseJava8Style, equalTo("Tanishq is Name My"));
}
}Reverse the words in String
A similar exercise could be to reverse the words themselves within a given string input.
Input
this is sample
Output
siht si elpmas
Implementation
-
Tokenize each word using
String.split()method and create an array of words. -
Loop through the string array and use
StringBuilder.reverse()method to reverse each word. -
Join all reversed words to create the resulting string.
Reverse the words in a string
public class Util {
public void reverseWordsInString(String input) {
String[] words = input.split(" ");
StringBuilder reverseString = new StringBuilder();
for (String word : words) {
String reverseWord = new StringBuilder(word).reverse().toString();
reverseString.append(reverseWord).append(" ");
}
System.out.println("reverseWordsString = " + reverseString);
}
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