How To Compare String Past Times Their Length Inwards Java?

One of the mutual programming tasks is to compare String, sometimes yesteryear their value in addition to sometimes yesteryear their length. The natural agency to compare String is the lexicographic way, which is implemented inwards the compareTo() method of String class, but sometimes you lot demand to compare String yesteryear their length. You cannot job the default compareTo() method for that task, you lot demand to write your ain custom Comparator, which tin forcefulness out compare String yesteryear length. Don't worry, It's slowly to compare multiple String yesteryear their length, all you lot demand to exercise is write a Comparator implementation which calculates their length using the length() method in addition to compares them.

Such comparator should render a positive value if get-go String has a length greater than minute String, a negative value if the length of get-go String is less than the length of minute String in addition to goose egg if both String has the same length.

You tin forcefulness out define such one-off Comparator yesteryear using Anonymous inner class equally shown inwards this article in addition to farther job it to variety a listing of String on their length.

This is a really useful technique in addition to plant fine inwards Java half dozen in addition to vii but plant fantastically good inwards Java 8 due to less clutter provided yesteryear the construct novel characteristic called lambda expressions.

Here is how you lot tin forcefulness out exercise it pre Java 8 earth :

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

In Java 8 world, it's fifty-fifty simpler yesteryear using lambda facial expression in addition to novel default methods added on java.util.Comparator class equally shown below :

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

Here are a in addition to b are 2 String object. This Integer.compare() is a novel method added to Java 8. Since nosotros are using Comparator of String, the compiler is besides smart plenty to infer the types of a in addition to b, which is, of course, String.

If you lot are interested, delight see Java 8 New Features inwards Simple Way to larn to a greater extent than almost novel methods added on Comparator class in addition to several other Java 8 features which tin forcefulness out construct your day-to-day life easy.

How to variety List of String yesteryear their length inwards Java vii in addition to 8

Here is an instance of using this String length comparator to variety a listing of String yesteryear their length.  In this program, nosotros stimulate got demonstrated both JDK half dozen in addition to vii agency yesteryear using Anonymous class in addition to novel Java 8 agency yesteryear using lambda expressions.

Java 8

import java.util.ArrayList; import java.util.Arrays; import java.util.Comparator; import java.util.List;   /*  * Java Program to variety listing of String yesteryear their length inwards JDK 8  */  public class SortingListOfStringByLength{    public static void main(String[] args) {             // In Java 8     System.out.println("Sorting List of String yesteryear length inwards 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 afterward sorting string yesteryear length");     System.out.println(cities);   } }  Output Sorting List of String yesteryear length in Java 8 ====== The master copy list without sorting [London, Tokyo, NewYork] The same list afterward sorting string yesteryear length [Tokyo, London, NewYork]

You tin forcefulness out come across that the Java 8 agency takes simply ane trouble in addition to it's a lot easier to sympathize ane time you lot acquire familiar amongst the syntax of lambda expressions.

If you lot desire to larn to a greater extent than almost lambda facial expression in addition to other useful Java SE 8 features, I besides propose you lot join The Complete Java MasterClass which volition instruct you lot non why in addition to how to job lambda expressions inwards Java 8.

Now, let's come across how you lot tin forcefulness out compare String yesteryear their length inwards pre-Java 8 world, I hateful amongst Java half dozen in addition to 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 variety listing of String yesteryear 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 yesteryear length inwards 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 afterward sorting string yesteryear length");     System.out.println(books);   } }  Output Sorting List of String yesteryear length in JDK 7 ====== The master copy list without sorting [Effective Java, Algorithms, Refactoring] The same list afterward sorting string yesteryear length [Algorithms, Refactoring, Effective Java]

That's all almost how to compare String yesteryear their length in addition to how you lot tin forcefulness out variety a listing of String yesteryear their length inwards Java vii in addition to Java 8. You tin forcefulness out come across it a lot to a greater extent than convenient inwards Java 8 equally you lot tin forcefulness out exercise custom Comparator inwards simply ane trouble yesteryear 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 yesteryear using the thenComparing() method you lot tin forcefulness out chain multiple comparators. See Java SE 8 for Really Impatient for to a greater extent than illustrated instance of Comparator inwards Java 8.

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

How to exercise Map Reduce inwards Java 8? (example)

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

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

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

How to job the filter() amongst collections inwards Java 8? (example)

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

How to implement Comparator inwards Java 8? (tutorial)

How to job peek() method of Stream inwards Java 8? (example)

How to job String.join() method inwards Java 8? (tutorial)

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

20 Example of LocalDate in addition to LocalTime inwards Java 8 (see here)

How to job Stream.flatMap inwards Java 8(example)

Difference betwixt map() in addition to flatMap() inwards Java 8? (answer)

How to job Stream.map() inwards Java 8 (example)

5 Books to Learn Java 8 in addition to Functional Programming (list)

5 Free Courses to larn Java 8 in addition to ix (courses)

Java 8 Interview Questions amongst Answers (course)

Thanks for reading this article hence far. If you lot liked this article in addition to hence delight part amongst your friends in addition to colleagues. If you lot stimulate got whatever questions or feedback in addition to hence delight driblet a note.

P.S.: If you lot simply desire to larn to a greater extent than almost novel features inwards Java 8 in addition to hence delight come across the course What's New inwards Java 8. It explains all the of import features of Java 8 e.g. lambda expressions, streams, functional interfaces, Optional, novel Date Time API in addition to other miscellaneous changes.

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