$show=/label

Java 8 Streams - Checking Whether String is Palindrome Or Not

SHARE:

A quick guide to check the given string is palindrome or not in java and java 8 streams.

1. Overview

In this tutorial, We'll learn how to check the given string is palindrome or not in java 8 programming.

Palindrome means when the string is reversed, it is as same as the original string.

Example: Input string is abcba and when it is revered abcba. Here both are same so this string is called as palindrome.

Java 8 Streams - Checking Whether String is Palindrome Or Not


2. Java Check String Palindrome - Two Pointers


This is a simple solution without using java 8 concepts. Here we take two pointer right and left. 
right value is initialed with 0 and left is with string length -1.

We take these two indexes values from string using charAt(index) method and compares them inside a while loop. If these two are not same then the given string is not a palindrome.

If equals, then increment right by 1 and decrement left by 1.
Repeat the comparisons steps until the right >= left or for any unmatch.

Look at the below example.
package com.javaprogramto.programs.strings.palindrome;

public class StringCheckPalindrome1 {

	public static void main(String[] args) {

		String input1 = "hello";
		boolean isPalindrome = isPalindrome(input1);
		System.out.println("Is " + input1 + " palindrome? " + isPalindrome);

		String input2 = "abcba";
		isPalindrome = isPalindrome(input2);
		System.out.println("Is " + input2 + " palindrome? " + isPalindrome);
	}

	private static boolean isPalindrome(String input) {

		int right = 0;
		int left = input.length() - 1;

		while (right <= left) {

			if (input.charAt(right) != input.charAt(left)) {
				return false;
			}

			right++;
			left--;
		}

		return true;
	}

}

Output:
Is hello palindrome? false
Is abcba palindrome? true

3. Java Check String Palindrome - for loop


Can we reduce no of lines from the above code? Yes by using for loop.
package com.javaprogramto.programs.strings.palindrome;

public class StringCheckPalindrome2 {

	public static void main(String[] args) {

		String input1 = "hello";
		boolean isPalindrome = isPalindromeWithForLoop(input1);
		System.out.println("Is " + input1 + " palindrome? " + isPalindrome);

		String input2 = "abcba";
		isPalindrome = isPalindromeWithForLoop(input2);
		System.out.println("Is " + input2 + " palindrome? " + isPalindrome);
	}

	private static boolean isPalindromeWithForLoop(String input) {
		
		int length = input.length();
		for (int i = 0; i < length; i++) {

			if (input.charAt(i) != input.charAt(length - i - 1)) {
				return false;
			}

		}

		return true;
	}

}

This code generates the same about as same as 2 pointer example.

4. Java Check String Palindrome - StringBuilder


Next, Can we reduce the above code to single line ? Answer is yes. It is done with the help of StringBuilder class and using its reverse() method.

reverse() method is to reverse the given input string and then compares it with the original input string.

	private static boolean isPalindromeWithStringBuilder(String input) {

		return input.equals(new StringBuilder(input).reverse().toString());
	}


This code also work without any errors and produces the same output.

5. Java 8 Program To Check String Palindrome 


Next, We'll see how to check the string palindrome in java 8 functional style programming.

Call IntStream.range() method with 0 to length/2. This is like running a loop from string index 0 to its length/2.

Next, call noneMatch() method with the predicate condition. This method returns true if no value is matched to the given predicate.

The solution can be implemented in a single line to make the code clean.

Look at the below code.
package com.javaprogramto.programs.strings.palindrome;

import java.util.stream.IntStream;

public class StringCheckPalindrome4 {

	public static void main(String[] args) {

		String input1 = "hello";
		boolean isPalindrome = isPalindromeInJava8(input1);
		System.out.println("Is " + input1 + " palindrome? " + isPalindrome);

		String input2 = "abcba";
		isPalindrome = isPalindromeInJava8(input2);
		System.out.println("Is " + input2 + " palindrome? " + isPalindrome);
	}

	private static boolean isPalindromeInJava8(String input) {

		return IntStream.range(0, input.length() / 2)
				.noneMatch(index -> input.charAt(index) != input.charAt(input.length() - index - 1));

	}

}

6. Conclusion


In this article, We've seen how to check the string is palindrome or not in older java and new java 8 streams api.



COMMENTS

BLOGGER

About Us

Author: Venkatesh - I love to learn and share the technical stuff.
Name

accumulo,1,ActiveMQ,2,Adsense,1,API,37,ArrayList,18,Arrays,21,Bean Creation,3,Bean Scopes,1,BiConsumer,1,Blogger Tips,1,Books,1,C Programming,1,Collection,8,Collections,32,Collector,1,Command Line,1,Compile Errors,1,Configurations,7,Constants,1,Control Statements,8,Conversions,6,Core Java,135,Corona India,1,Create,2,CSS,1,Date,3,Date Time API,38,Dictionary,1,Difference,2,Download,1,Eclipse,3,Efficiently,1,Error,1,Errors,1,Exceptions,7,Fast,1,Files,17,Float,1,Font,1,Form,1,Freshers,1,Function,3,Functional Interface,2,Garbage Collector,1,Generics,4,Git,9,Grant,1,Grep,1,HashMap,2,HomeBrew,2,HTML,2,HttpClient,2,Immutable,1,Installation,1,Interview Questions,6,Iterate,2,Jackson API,3,Java,32,Java 10,1,Java 11,6,Java 12,5,Java 13,2,Java 14,2,Java 8,127,Java 8 Difference,2,Java 8 Stream Conversions,4,java 8 Stream Examples,12,Java 9,1,Java Conversions,14,Java Design Patterns,1,Java Files,1,Java Program,3,Java Programs,113,Java Spark,1,java.lang,4,java.util. function,1,JavaScript,1,jQuery,1,Kotlin,11,Kotlin Conversions,6,Kotlin Programs,10,Lambda,2,lang,29,Leap Year,1,live updates,1,LocalDate,1,Logging,1,Mac OS,3,Math,1,Matrix,6,Maven,1,Method References,1,Mockito,1,MongoDB,3,New Features,1,Operations,1,Optional,6,Oracle,5,Oracle 18C,1,Partition,1,Patterns,1,Programs,1,Property,1,Python,2,Quarkus,1,Read,1,Real Time,1,Recursion,2,Remove,2,Rest API,1,Schedules,1,Serialization,1,Servlet,2,Sort,1,Sorting Techniques,8,Spring,2,Spring Boot,23,Spring Email,1,Spring MVC,1,Streams,29,String,61,String Programs,28,String Revese,1,Swing,1,System,1,Tags,1,Threads,11,Tomcat,1,Tomcat 8,1,Troubleshoot,24,Unix,3,Updates,3,util,5,While Loop,1,
ltr
item
JavaProgramTo.com: Java 8 Streams - Checking Whether String is Palindrome Or Not
Java 8 Streams - Checking Whether String is Palindrome Or Not
A quick guide to check the given string is palindrome or not in java and java 8 streams.
https://1.bp.blogspot.com/-go53P3-iVhQ/YYpNWeqbfSI/AAAAAAAADbg/KULL1kPf0XYuvXcbXzr0znRgPv8L9XbCgCLcBGAsYHQ/w400-h295/Java%2B8%2BStreams%2B-%2BChecking%2BWhether%2BString%2Bis%2BPalindrome%2BOr%2BNot.png
https://1.bp.blogspot.com/-go53P3-iVhQ/YYpNWeqbfSI/AAAAAAAADbg/KULL1kPf0XYuvXcbXzr0znRgPv8L9XbCgCLcBGAsYHQ/s72-w400-c-h295/Java%2B8%2BStreams%2B-%2BChecking%2BWhether%2BString%2Bis%2BPalindrome%2BOr%2BNot.png
JavaProgramTo.com
https://www.javaprogramto.com/2021/11/%20java-8-streams-string-palindrome.html
https://www.javaprogramto.com/
https://www.javaprogramto.com/
https://www.javaprogramto.com/2021/11/%20java-8-streams-string-palindrome.html
true
3124782013468838591
UTF-8
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THIS PREMIUM CONTENT IS LOCKED STEP 1: Share to a social network STEP 2: Click the link on your social network Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy Table of Content