How to compare String yesteryear their length inwards Java seven as well as 8?

The natural agency to compare String is the lexicographic way, which is implemented inwards the compareTo() method of String class, but sometimes yous demand to compare String past times their length. You cannot usage the default compareTo() method for that task, yous demand to write your ain custom Comparator, which tin reach notice compare String past times length. Don't worry, It's slow to compare multiple String past times their length, all yous demand to write is a Comparator which calculates their length using the length() method in addition to compare them. Such comparator should render a positive value if start String has a length greater than minute String, a negative value if the length of start String is less than the length of minute String in addition to goose egg if both String has the same length.

You tin reach notice define such one-off Comparator past times using Anonymous inner shape equally shown inwards this article in addition to farther usage it to kind 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 past times the build novel characteristic called lambda expressions.

Here is how yous tin reach notice practise it pre Java 8 the world :

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 seem in addition to novel default methods added on java.util.Comparator shape equally shown below :

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

Here are a in addition to 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 likewise smart plenty to infer the types of a in addition to b, which is, of course, String.Please see Java SE 8 for Really Impatient By Cay S. Horstmann to acquire to a greater extent than well-nigh novel methods added on Comparator shape in addition to several other Java 8 features which tin reach notice build your day-to-day life easy.

How to kind List of String past times their length inwards Java vii in addition to 8

Here is an event of using this String length comparator to kind a listing of String past times their length. In this program, nosotros cause got demonstrated both JDK half dozen in addition to vii agency past times using Anonymous shape in addition to novel Java 8 agency past times using lambda expressions. You tin reach notice run into that the Java 8 agency takes but i job in addition to it's a lot easier to empathise i time yous acquire familiar alongside the syntax of lambda expressions. See Java 8 inwards Action past times Raoul-Gabriel Urma to acquire to a greater extent than well-nigh why in addition to how to usage lambda expressions inwards Java 8.

The natural agency to compare String is the lexicographic agency How to compare String past times their length inwards Java vii in addition to 8?

Java 6, 7

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 inwards JDK vii ======");     System.out.println("The master 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 subsequently sorting string past times length");     System.out.println(books);   } }  Output Sorting List of String past times length in JDK 7 ====== The master list without sorting [Effective Java, Algorithms, Refactoring] The same list subsequently sorting string past times length [Algorithms, Refactoring, Effective Java]

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

That's all well-nigh how to compare String past times their length in addition to how yous tin reach notice kind a listing of String past times their length inwards Java vii in addition to Java 8. You tin reach notice run into it lot to a greater extent than convenient inwards Java 8 equally yous tin reach notice practise custom Comparator inwards but i job past times using the lambda expression. The JDK 8 API is amount of such methods to faciliate fifty-fifty to a greater extent than complex comparing e.g. by using thenComparing() method yous tin reach notice chain multiple comparators. See Java SE 8 for Really Impatient for to a greater extent than illustrated event of Comparator inwards Java 8.