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Articles by Maruthi Krishna
Page 39 of 50
Regular Expression "re*" Metacharacter in Java
The subexpression/metacharacter “re*” matches 0 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 MatchAllCharacters ...
Read MoreExplain Regular Expression "A" Metacharacter in Java
The subexpression/metacharacter “\A” matches the beginning of the entire string.Example 1import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample { public static void main( String args[] ) { String regex = "\AHi"; 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: 1Example2Following Java program accepts a string ...
Read MoreRegular Expression "$" (dollar) Metacharacter in Java
The subexpression/metacharacter “$” matches the end of a line.Example 1import java.util.regex.Matcher; import java.util.regex.Pattern; public class EndWith { public static void main( String args[] ) { String regex = "Tutorialspoint$"; 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 2The following Java program accepts ...
Read MoreRegular Expression "^" (caret) Metacharacter in Java
The subexpression/metacharacter “^” matches the beginning of a line. If you use this in a regular expression, it matches the sentence succeeding it in the input string.Example 1import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample { public static void main( String args[] ) { String regex = "^Hi how are you"; 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++; ...
Read MoreWhat is meant by re-throwing exceptions in Java?
When an exception is cached in a catch block, you can re-throw it using the throw keyword (which is used to throw the exception objects).While re-throwing exceptions you can throw the same exception as it is without adjusting it as −try { int result = (arr[a])/(arr[b]); System.out.println("Result of "+arr[a]+"/"+arr[b]+": "+result); } catch(ArithmeticException e) { throw e; }Or, wrap it within a new exception and throw it. When you wrap a cached exception within another exception and throw it, it is known as exception chaining or, exception wrapping, by doing this you can adjust your exception, throwing a ...
Read MoreWhat is ArrayStoreException in Java?
When you have created an array of a particular data type with fixed size and populate it if you store a value other than its datatype an ArrayStoreException is thrown at the run time.ExampleIn the following Java program, we are creating an Integer array and trying to store a double value in it. Live Demoimport java.util.Arrays; public class ArrayStoreExceptionExample { public static void main(String args[]) { Number integerArray[] = new Integer[3]; integerArray[0] = 12548; integerArray[1] = 36987; integerArray[2] = 555.50; integerArray[3] = 12548; ...
Read MoreHow to avoid ConcurrentModificationException while iterating a collection in java?
When you are working with collection objects, while one thread is iterating over a particular collection object, if you try to add or remove elements from it, a ConcurrentModificationException will be thrown.Not only that, If you are iterating a collection object, add or remove elements to it and try to iterate its contents again it is considered that you are trying to access the collection object using multiple threads and ConcurrentModificationException is thrown.Example Live Demoimport java.util.ArrayList; import java.util.Iterator; public class OccurenceOfElements { public static void main(String args[]) { ArrayList list = new ArrayList(); ...
Read MoreHow to insert an object in an ArrayList at a specific position in java?
The add() method of the ArrayList class helps you to add elements to an array list. It has two variants −add(E e) − This method accepts an object/elements as a parameter and adds the given element at the end of the list.public void add(int index, E element) − This method accepts an element and an integer value representing the position at which we need to insert it and inserts the specified element at the specified position in this list. Shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices).Therefore ...
Read MoreDifference between next() and hasNext() in java collections?
Java provides Iterator and ListIterator classes to retrieve the elements of the collection objects.The hasNext() methodThe hasNext() method of these interfaces returns true if the collection object has the next element else it returns false.Example Live Demoimport java.util.ArrayList; import java.util.Iterator; public class hasNextExample{ public static void main(String[] args){ ArrayList list = new ArrayList(); //Instantiating an ArrayList object list.add("JavaFX"); list.add("Java"); Iterator it = list.iterator(); System.out.println(it.hasNext()); it.next(); System.out.println(it.hasNext()); it.next(); System.out.println(it.hasNext()); ...
Read MoreHow to remove the redundant elements from an ArrayList object in java?
The interface set does not allow duplicate elements. The add() method of this interface accepts elements and adds to the Set object, if the addition is successful it returns true if you try to add an existing element using this method, the addition operations fails to return false.Therefore, to remove redundant elements of an ArrayList object −Get/create the required ArrayList.Create an empty set object.Try to add all the elements of the ArrayList object to set objectives.Clear the contents of the ArrayList using the clear() method.Now, using the addAll() method add the contents of the set object to the ArrayList again.Example Live ...
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