$show=/label

Java String API matches​() Method Example

SHARE:

Quick guide to Java String API matches​() Method Example and How to test string against regular expression. Syntax: public boolean matches​(String regex)

1. Java String API matches​(String regex) Overview

In this tutorial, We'll learn about Java String API matches​() Method with Example programs. And also will explain how this method works internally.

matches() method tells whether or not this string matches the given regular expression.

In simple words, First regular expression is a pattern which tells string should have only alphabetic's or numbers. This pattern can be anything or specified character set.

If the string fits into the specified regular expression pattern then matches() method returns true. Otherwise returns false.



Java String API matches​() Method Example


1.1 Syntax


public boolean matches​(String regex)


This is a public method and can be invoked directly on instance.

1.2 Parameters


This takes only one parameter and it is String regex.

This should be a valid regex parameter.

1.3 Returns


boolean. true or false.

1.4 Since


Java 1.4

1.5 Throws Exception


This method throws PatternSyntaxException if the regular expression provided is invalid.

Read article on Java 12 String new Additions.

2. String matches​() Method Example


We will write example programs on matches method.

2.1 Check String has "java" word using matches()


Below java program to check the string has "java" word in it using matches() method. We should pass a valid regex pattern to this method.

// Example 1 to check word 'java'
String str1 = "Welcome to java-w3schools";
boolean isMatch = str1.matches("(.*)java(.*)");
System.out.println(" Does input str1 has 'java' word : "+isMatch);


Here, Passed regex checks for 'java' word.
       
Output:

Does input str1 has 'java' word : true

Now, will change the pattern to find word 'world'. But, input is not having word 'world'.

isMatch = str1.matches("(.*)world(.*)");
System.out.println("Does input str1 has 'world' word : "+isMatch);

Output:

Does input str1 has 'world' word : false


This program returned false because input did not have word 'world'

2.2 Example to Check if a string contains only alphabets


Now, We will write a program to check if string is having only alphabetic's or not.

For this we should pass a regex which covers a to z and A to Z as well one blank space ' '. Because string may have multiple words,

// Example 2: Checking only alphabets -
String str2 = "Google is very popular search engine";
isMatch = str2.matches("[a-zA-Z ]+");
System.out.println("Does input str2 has only alphabetics: "+isMatch);

Output:

Does input str2 has only alphabetics: true

If input has numeric like below along with alphabetic's.

String str3 = "Google is very popular search engine and it is No 1";
isMatch = str3.matches("[a-zA-Z ]+");

Output:

Does input str3 has only alphabetics: false

It returned false because input str3 has digit '1'.

 2.3 Example program to check if String contains only numbers

The below program checks for only digits from 0 to 9. If it finds any character other than that will return false.

// Example 3: Checking only numerics
String str4 = "16784311299";
isMatch = str4.matches("[0-9]+");
System.out.println("Does input str4 has only numerics: "+isMatch);

Output:

Does input str4 has only numerics: true

2.4 Example to throw PatternSyntaxException


Just need to pass the invalid regex. This should be good to see the exception.

isMatch = str4.matches("[0-**9]+($$");

Full Exception Stack:

Exception in thread "main" java.util.regex.PatternSyntaxException: Illegal character range near index 3
[0-**9]+($$
   ^
 at java.base/java.util.regex.Pattern.error(Pattern.java:2015)
 at java.base/java.util.regex.Pattern.range(Pattern.java:2813)
 at java.base/java.util.regex.Pattern.clazz(Pattern.java:2701)
 at java.base/java.util.regex.Pattern.sequence(Pattern.java:2126)
 at java.base/java.util.regex.Pattern.expr(Pattern.java:2056)
 at java.base/java.util.regex.Pattern.compile(Pattern.java:1778)
 at java.base/java.util.regex.Pattern.(Pattern.java:1427)
 at java.base/java.util.regex.Pattern.compile(Pattern.java:1068)
 at java.base/java.util.regex.Pattern.matches(Pattern.java:1173)
 at java.base/java.lang.String.matches(String.java:2033)
 at com.java.w3schools.blog.string.StringMatchesExample.main(StringMatchesExample.java:36)

3. matches() Internal Code


matches() method internal code is below.

public boolean matches(String regex) {
    return Pattern.matches(regex, this);
}

Step 1: It calls simply Pattern.matches() method. It will pass regex and input string.

Step 2: It invokes Pattern.compile(regex) method to check the given regex is valid or not. If it is not valid then will throw PatternSyntaxException exception. If valid then it creates Pattern object.
Step 3: Next, Creates Matcher object by calling p.matcher(input).
Step 4: At last, invokes matches() on Matcher object which created in above step. matches() method returns true if ok. Otherwise, it returns false.

Note: An invocation of this method of the form str.matches(regex) yields exactly the same result as the expression


Pattern.matches(regex, str) 


4. Conclusion


In this article, We've learn about Java String API matches() method. How to validate a string against a valid regular expression.

Written example programs to check string has only alphabetics or numerics.

Discussed detailed on how matches() method works internally and how it is implemented.

Example code snippets shown in this article is available on GitHub.

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,24,Bean Creation,3,Bean Scopes,1,BiConsumer,1,Blogger Tips,1,Books,1,C Programming,1,Collection,8,Collections,37,Collector,1,Command Line,1,Comparator,1,Compile Errors,1,Configurations,7,Constants,1,Control Statements,8,Conversions,6,Core Java,149,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,8,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 8,128,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,114,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,31,String,61,String Programs,28,String Revese,1,StringBuilder,1,Swing,1,System,1,Tags,1,Threads,11,Tomcat,1,Tomcat 8,1,Troubleshoot,26,Unix,3,Updates,3,util,5,While Loop,1,
ltr
item
JavaProgramTo.com: Java String API matches​() Method Example
Java String API matches​() Method Example
Quick guide to Java String API matches​() Method Example and How to test string against regular expression. Syntax: public boolean matches​(String regex)
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEip_qY7AsMENiSS7FWude6lf8xdtoPtgN7xcjTJxXALotAvel4WLErkn2tH8PLRyaUk6IITARu4u1uxSLbhzhM7PscV8qsO2Fw2CtJMte6ghwJGfdWv1nCFlpsj8Py5mDA_d-jr-ib2U84/s320/Java+String+API+matches%25E2%2580%258B%2528%2529+Method+Example.PNG
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEip_qY7AsMENiSS7FWude6lf8xdtoPtgN7xcjTJxXALotAvel4WLErkn2tH8PLRyaUk6IITARu4u1uxSLbhzhM7PscV8qsO2Fw2CtJMte6ghwJGfdWv1nCFlpsj8Py5mDA_d-jr-ib2U84/s72-c/Java+String+API+matches%25E2%2580%258B%2528%2529+Method+Example.PNG
JavaProgramTo.com
https://www.javaprogramto.com/2019/05/java-string-matches.html
https://www.javaprogramto.com/
https://www.javaprogramto.com/
https://www.javaprogramto.com/2019/05/java-string-matches.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