In this example we are going to talk aboutmatchesString Class method. You can use this method to test aString against a regular expression. Testing aString against a regular expression is a very common operation for interactive applications, as it is heavily used to perform validity checks on user input. It can also be used for several other causes on a bigger scale, like filtering, pruning on large text data, searching text documents etc.

So as you might imagine, Java offersmatches as a very simple API method to test Strings against regular expressions.

Let’s see some examples:

• Check if a sentence has only letters : [a-zA-Z *]+$

StringMacthesExample.java:

package com.javacodegeeks.core.string;public class StringMacthesExample {public static void main(String[] args) {String s1 = "Java Code Geeks are awesome";System.out.println(s1.matches("[a-zA-Z *]+$"));}}

Output:

true

• Check if a sentence has only alphanumerics : [a-zA-Z0-9 *]+$

StringMacthesExample.java:

package com.javacodegeeks.core.string;public class StringMacthesExample {public static void main(String[] args) {String s1 = "Java 1 Code 2 Geeks 3 are awesome 15675";System.out.println(s1.matches("[a-zA-Z0-9 *]+$"));}}

Output:

true

• Check if a string is an alphanumeric word: \w*$

StringMacthesExample.java:

package com.javacodegeeks.core.string;public class StringMacthesExample {public static void main(String[] args) {String s1 = "Java8Rocks";System.out.println(s1.matches("\\w*$"));}}

Output:

true

• Check if a string is a valid email address:^[_A-Za-z0-9-\+]+(\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\.[A-Za-z0-9]+)*(\.[A-Za-z]{2,})$

StringMacthesExample.java:

package com.javacodegeeks.core.string;public class StringMacthesExample {public static void main(String[] args) {System.out.println("james.harlem@javacodegeeks.com".matches("^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@"+ "[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*"+ "(\\.[A-Za-z]{2,})$"));}}

Output:

true

So there you go. To learn more about Regular expression syntax you can checkoutthis site.

Download the Source Code

This was a Java String matches Example. You can download the source code of this example here : StringMatchesExample.zip

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