How To Compare String Yesteryear Their Length Inward Java?

One of the mutual programming tasks is to compare String, sometimes past times their value as well as sometimes past times their length. The natural agency to compare String is the lexicographic way, which is implemented inward the compareTo() method of String class, but sometimes yous demand to compare String past times their length. You cannot utilisation the default compareTo() method for that task, yous demand to write your ain custom Comparator, which tin compare String past times length. Don't worry, It's slowly to compare multiple String past times their length, all yous demand to practise is write a Comparator implementation which calculates their length using the length() method as well as compares them.

Such comparator should render a positive value if kickoff String has a length greater than minute String, a negative value if the length of kickoff String is less than the length of minute String as well as goose egg if both String has the same length.

You tin define such one-off Comparator past times using Anonymous inner class every bit shown inward this article as well as farther utilisation it to kind a listing of String on their length.

This is a real useful technique as well as plant fine inward Java vi as well as vii but plant fantastically good inward Java 8 due to less clutter provided past times the construct novel characteristic called lambda expressions.

Here is how yous tin practise it pre Java 8 basis :

public int compare(String s1, String s2) {     return s1.length() - s2.length(); }

In Java 8 world, it's fifty-fifty simpler past times using lambda facial expression as well as novel default methods added on java.util.Comparator shape every bit shown below :

Comparator<String> strlenComp = (a, b) -> Integer.compare(a.length(), b.length());

Here are a as well as b are ii String object. This Integer.compare() is a novel method added to Java 8. Since nosotros are using Comparator of String, the compiler is every bit good smart plenty to infer the types of a as well as b, which is, of course, String.

If yous are interested, delight see Java 8 New Features inward Simple Way to acquire to a greater extent than well-nigh novel methods added on Comparator shape as well as several other Java 8 features which tin construct your day-to-day life easy.

How to kind List of String past times their length inward Java vii as well as 8

Here is an instance of using this String length comparator to kind a listing of String past times their length.  In this program, nosotros get got demonstrated both JDK vi as well as vii agency past times using Anonymous shape as well as novel Java 8 agency past times using lambda expressions.

Java 8

import java.util.ArrayList; import java.util.Arrays; import java.util.Comparator; import java.util.List;   /*  * Java Program to kind listing of String past times their length inward JDK 8  */  public class SortingListOfStringByLength{    public static void main(String[] args) {             // In Java 8     System.out.println("Sorting List of String past times length inward Java 8 ======");     List<String> cities = new ArrayList<>(Arrays.asList("London",                                                  "Tokyo", "NewYork"));     System.out.println("The master copy listing without sorting");     System.out.println(cities);      cities.sort((first, second) -> Integer.compare(first.length(),                                                    second.length()));          System.out.println("The same listing later sorting string past times length");     System.out.println(cities);   } }  Output Sorting List of String past times length in Java 8 ====== The master copy list without sorting [London, Tokyo, NewYork] The same list later sorting string past times length [Tokyo, London, NewYork]

You tin meet that the Java 8 agency takes but i business as well as it's a lot easier to empathise i time yous acquire familiar alongside the syntax of lambda expressions.

If yous desire to acquire to a greater extent than well-nigh lambda facial expression as well as other useful Java SE 8 features, I every bit good propose yous join The Complete Java MasterClass which volition instruct yous non why as well as how to utilisation lambda expressions inward Java 8.

Now, let's meet how yous tin compare String past times their length inward pre-Java 8 world, I hateful alongside Java vi as well as Java vii versions.

Before Java 8

import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.Comparator; import java.util.List;   /*  * Java Program to kind listing of String past times their length  */  public class StringComparisonByLength{    public static void main(String[] args) {      List<String> books = new ArrayList<>(Arrays.asList("Effective Java",                                     "Algorithms", "Refactoring" ));     System.out.println("Sorting List of String past times length inward JDK vii ======");     System.out.println("The master copy listing without sorting");     System.out.println(books);          Comparator<String> byLength = new Comparator<String>(){       @Override       public int compare(String s1, String s2) {         return s1.length() - s2.length();         }     };          Collections.sort(books, byLength);     System.out.println("The same listing later sorting string past times length");     System.out.println(books);   } }  Output Sorting List of String past times length in JDK 7 ====== The master copy list without sorting [Effective Java, Algorithms, Refactoring] The same list later sorting string past times length [Algorithms, Refactoring, Effective Java]

That's all well-nigh how to compare String past times their length as well as how yous tin kind a listing of String past times their length inward Java vii as well as Java 8. You tin meet it a lot to a greater extent than convenient inward Java 8 every bit yous tin practise custom Comparator inward but i business past times using the lambda expression.

The JDK 8 API is amount of such methods to facilitate fifty-fifty to a greater extent than complex comparing similar past times using the thenComparing() method yous tin chain multiple comparators. See Java SE 8 for Really Impatient for to a greater extent than illustrated instance of Comparator inward Java 8.

Further Learning
The Complete Java MasterClass
Java 8 New Features inward Simple Way
here)

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10 Example of forEach() method inward Java 8 (example)

How to parse String to LocalDate inward Java 8? (program)

10 Example of Joining String inward Java 8 (see here) 

How to utilisation the filter() alongside collections inward Java 8? (example)

10 Example of Stream API inward Java 8 (see here)

How to implement Comparator inward Java 8? (tutorial)

How to utilisation peek() method of Stream inward Java 8? (example)

How to utilisation String.join() method inward Java 8? (tutorial)

10 Example of converting a List to Map inward Java 8 (example)

20 Example of LocalDate as well as LocalTime inward Java 8 (see here)

How to utilisation Stream.flatMap inward Java 8(example)

Difference betwixt map() as well as flatMap() inward Java 8? (answer)

How to utilisation Stream.map() inward Java 8 (example)

5 Books to Learn Java 8 as well as Functional Programming (list)

5 Free Courses to acquire Java 8 as well as nine (courses)

Java 8 Interview Questions alongside Answers (course)

Thanks for reading this article thus far. If yous liked this article thus delight percentage alongside your friends as well as colleagues. If yous get got whatsoever questions or feedback thus delight drib a note.

P.S.: If yous but desire to acquire to a greater extent than well-nigh novel features inward Java 8 thus delight meet the course What's New inward Java 8. It explains all the of import features of Java 8 e.g. lambda expressions, streams, functional interfaces, Optional, novel Date Time API as well as other miscellaneous changes.