Object Oriented Programming Articles

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What is difference between matches() and find() in Java Regex?

Maruthi Krishna
Maruthi Krishna
Updated on 20-Nov-2019 767 Views

The java.util.regex.Matcher class represents an engine that performs various match operations. There is no constructor for this class, you can create/obtain an object of this class using the matches() method of the class java.util.regex.Pattern.Both matches() and find() methods of the Matcher class tries to find the match according to the regular expression in the input string. In case of a match, both returns true and if a match is not found both methods return false.The main difference is that the matches() method try to match the entire region of the given input i.e. if you are trying to search for ...

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Pattern asPredicate() method in Java with examples

Maruthi Krishna
Maruthi Krishna
Updated on 20-Nov-2019 360 Views

The Predicate interface of the java.util.function package can be used as a target for lambda expressions. The test method of this interface accepts a value ad validates it with the current value of the Predicate object. This method returns true in-case of a match, else false.The asPredicate() method of the java.util.regex.Pattern class returns a Predicate object which can match a string with the regular expression using which the current Pattern object was compiled.Example 1import java.util.Scanner; import java.util.function.Predicate; import java.util.regex.Pattern; public class AsPredicateExample {    public static void main( String args[] ) {       //Reading string value     ...

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Pattern DOTALL field in Java with examples

Maruthi Krishna
Maruthi Krishna
Updated on 20-Nov-2019 4K+ Views

The DOTALL field of the Pattern class Enables dotall mode. By default, the “.” Meta character in regular expressions matches all characters except line terminators.Example 1import java.util.regex.Matcher; import java.util.regex.Pattern; public class DOTALL_Example {    public static void main( String args[] ) {       String regex = ".";       String input = "this is a sample this is second line";       Pattern pattern = Pattern.compile(regex);       Matcher matcher = pattern.matcher(input);       int count =0;       while(matcher.find()) {          count++;          System.out.print(matcher.group());     ...

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Pattern COMMENTS field in Java with examples

Maruthi Krishna
Maruthi Krishna
Updated on 20-Nov-2019 675 Views

The COMMENTS field of the Pattern class allows whitespace and comments in pattern. When you use this as flag value to the compile() method, white spaces and, comments starting with # are ignored in the given pattern.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class COMMENTES_Example {    public static void main( String args[] ) {       Scanner sc = new Scanner(System.in);       System.out.println("Enter input data: ");       String input = sc.nextLine();       //Regular expression to find digits       String regex = "\d #ignore this comment";       //Compiling ...

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Pattern CASE_INSENSITIVE field in Java with examples

Maruthi Krishna
Maruthi Krishna
Updated on 20-Nov-2019 2K+ Views

This CASE_INSENSITIVE field of the Pattern class matches characters irrespective of case. When you use this as flag value to the compile() method and if you search for characters using regular expressions characters of both cases will be matched.Note − By default, this flag matches only ASCII charactersExample 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class CASE_INSENSITIVE_Example {    public static void main( String args[] ) {       Scanner sc = new Scanner(System.in);       System.out.println("Enter input data: ");       String input = sc.nextLine();       System.out.println("Enter required character: ");       char ...

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Pattern splitAsStream() method in Java with examples

Maruthi Krishna
Maruthi Krishna
Updated on 20-Nov-2019 467 Views

The Pattern class of the java.util.regex package is a compiled representation of a regular expression.The splitAsStream() method of this class accepts a CharSequence object, representing the input string as a parameter and, at each match, it splits the given string into a new substring and returns the result as a stream holding all the substrings.Exampleimport java.util.regex.Pattern; import java.util.stream.Stream; public class SplitAsStreamMethodExample {    public static void main( String args[] ) {       //Regular expression to find digits       String regex = "(\s)(\d)(\s)";       String input = " 1 Name:Radha, age:25 2 Name:Ramu, age:32" + ...

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Explain the Java regular expression construct "re?".

Maruthi Krishna
Maruthi Krishna
Updated on 19-Nov-2019 239 Views

The subexpression/metacharacter “re?” matches 0 or 1 occurrence of the preceding expression.Example 1import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample {    public static void main( String args[] ) {       String regex = "Wel?";       String input = "Welcome to Tutorialspoint";       Pattern p = Pattern.compile(regex);       Matcher m = p.matcher(input);       int count = 0;       while(m.find()) {          count++;       }       System.out.println("Number of matches: "+count);    } }OutputNumber of matches: 1Example 2Following Java program accepts a string from ...

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Explain the Sub-Expression "(?> re)" in Java Regular Expressions

Maruthi Krishna
Maruthi Krishna
Updated on 19-Nov-2019 222 Views

The subexpression/metacharacter “(?> re)” matches the independent pattern without backtracking.Exampleimport java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class PatternExample {    public static void main(String args[]) {       //Reading String from user       System.out.println("Enter a String");       Scanner sc = new Scanner(System.in);       String input = sc.next();       String regex = "(?>[0-9])";       //Compiling the regular expression       Pattern pattern = Pattern.compile(regex);       //Retrieving the matcher object       Matcher matcher = pattern.matcher(input);       //verifying whether match occurred       boolean ...

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Sub-Expression "(?: re)" in Java Regular Expressions

Maruthi Krishna
Maruthi Krishna
Updated on 19-Nov-2019 234 Views

The subexpression/metacharacter “(?: re)” groups regular expressions without remembering the matched text.Exampleimport java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class PatternExample {    public static void main(String args[]) {       //Reading String from user       System.out.println("Enter a String");       Scanner sc = new Scanner(System.in);       String input = sc.next();       String regex = "(?:[0-9])";       //Compiling the regular expression       Pattern pattern = Pattern.compile(regex);       //Retrieving the matcher object       Matcher matcher = pattern.matcher(input);       //verifying whether match occurred     ...

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Regular Expression "(re)" Sub-Expression in Java

Maruthi Krishna
Maruthi Krishna
Updated on 19-Nov-2019 401 Views

The subexpression/metacharacter “( )” groups the regular expressions and remembers the matched text.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example {    public static void main( String args[] ) {       String input = "Hello how are you welcome to Tutorialspoint";       String regex = "H(ell|ow)";       //Compiling the regular expression       Pattern pattern = Pattern.compile(regex);       //Retrieving the matcher object       Matcher matcher = pattern.matcher(input);       if(matcher.find()) {          System.out.println("Match found");       } else {       ...

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