Java Articles - Page 148 of 440

The java.util.regex package of java provides various classes to find particular patterns in character sequences. The pattern class of this package is a compiled representation of a regular expression.To match a specific character from the given input string −Get the input string.This compile() method of this class accepts a string value representing a regular expression and an integer value representing a flag returns a Pattern object. Compile the regular expression bypassing −The pattern matcher “[ ]” with required character in it ex: “[t]”.The flag CASE_INSENSITIVE to ignore case.The matcher() method of the Pattern class accepts an input string and returns ... Read More

The com.fasterxml.jackson.databind.node.ObjectNode class can be used to map the JSON object structure in Json content. We can search for a particular value inside the JSON file using the get() method of ObjectNode class, this method used for accessing the value of a specified field of an object node.Syntaxpublic JsonNode get(String fieldName)Exampleimport com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.node.ObjectNode; public class ObjectNodeTest {    public static void main(String args[]) throws Exception {       String jsonString = "{\"Id\":101, \"name\":\"Raja Ramesh\", \"address\":\"Madhapur\"}";       ObjectMapper mapper = new ObjectMapper();       ObjectNode node = mapper.readValue(jsonString, ObjectNode.class);       if(node.has("name")) {       ... Read More

You can match the word boundaries using the meta character “\b”.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example {    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.nextLine();       String regex = "\b";       //Compiling the regular expression       Pattern pattern = Pattern.compile(regex);       //Retrieving the matcher object       Matcher matcher = pattern.matcher(input);       int count = 0;     ... Read More

The subexpression/metacharacter “\b” matches the word boundaries when outside the brackets. Matches the backspace (0x08) when inside the brackets.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample {    public static void main( String args[] ) {       String regex = "\bbecause\b";       Scanner sc = new Scanner(System.in);       System.out.println("Enter a string: ");       String input = sc.nextLine();       Pattern p = Pattern.compile(regex);       Matcher m = p.matcher(input);       int count = 0;       while(m.find()) {          count ++;   ... Read More

The subexpression/metacharacter “a| b” matches either a or b.Example 1import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample {    public static void main( String args[] ) {       String regex = "Hello|welcome";       String input = "Hello how are you 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: 2Example 2The following Java program reads gender ... Read More

The subexpression/metacharacter “re{ n, m}” matches at least n and at most m occurrences 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 = "xyy{2, 4}";       String input = "xxyyzxxyyyyxyyzxxyyzz";       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 2The following ... Read More

The subexpression/metacharacter “re{ n}” matches exactly n number of occurrences 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 = "to{1}";       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: 2Example 2Following Java program reads age ... Read More

The subexpression/metacharacter “re+” matches one or more occurrences 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 = "aabc+";       String input = "aabcabcaabcabbcaabcbcaabc";       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: 4Example 2import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Test ... Read More

The subexpression/metacharacter “\Z” matches the end of the entire string except allowable final line terminator.Example 1import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample {    public static void main( String args[] ) {       String regex = "Tutorialspoint\z";       String input = "Hi how are you 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 ... Read More

The subexpression/metacharacter “\G” matches the point where the last match finished.Exampleimport java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample {    public static void main( String args[] ) {       String regex = "\G[0-9]";       Scanner sc = new Scanner(System.in);       System.out.println("Enter a string: ");       String input = sc.nextLine();       Pattern p = Pattern.compile(regex);       Matcher m = p.matcher(input);       int count = 0;       String digits = "";       System.out.println("Digits in the previous match:");       while(m.find()) {   ... Read More