Found 9326 Articles for Object Oriented Programming

In order to get Array Dimensions in Java, we use the getClass(), isArray() and getComponentType() methods with decision making in combination with iterative statements.The getClass() method method returns the runtime class of an object. The getClass() method is a part of the java.lang.Object class.Declaration − The java.lang.Object.getClass() method is declared as follows −public final Class getClass()The isArray() method checks whether the passed argument is an array. It returns a boolean value, either true or falseSyntax - The isArray() method has the following syntaxArray.isArray(obj)The getComponentType() method returns the Class denoting the component type of an array. If the class is not an ... Read More

In order to get the array upperbound of a multidimensional array, we use the length() method. For a 2D array, the length() method returns the number of rows. We can access the number of columns using the array_name[0].length method.Let us see a program to get the array upperbound in Java Multidimensional arraysExample Live Demopublic class Example {    public static void main(String args[]) {       String[][] str = new String[5][10];       System.out.println("1st dimension : " + str.length); // displays the number of rows       System.out.println("2nd dimension : " + str[0].length); // displays the number of columns    } }Output1st dimension : 5 2nd dimension : 10

In order to create and demonstrate an immutable collection in Java, we use the unmodifiableCollection() method. This method returns an unmodifiable and immutable view of the collection.Declaration − The java.util.Collections.unmodifiableCollection() method is declared as follows -public static Collection unmodifiableCollection(Collection

In order to sort items of an ArrayList with Collections.reverseOrder() in Java, we need to use the Collections.reverseOrder() method which returns a comparator which gives the reverse of the natural ordering on a collection of objects that implement the Comparable interface.Declaration − The java.util.Collections.reverseOrder() method is declared as follows -public static Comparator reverseOrder()Let us see a program to sort an ArrayList with Collections.reverseOrder() in Java -Example Live Demoimport java.util.*; public class Example {    public static void main (String[] args) {       ArrayList list = new ArrayList();       list.add(10);       list.add(50);       ... Read More

To rotate elements of a collection in Java, we use the Collections.rotate() method. The rotate method rotates the elements specified in the list by a specified distance. When this method is invoked, the element at index x will be the element previously at index (x - distance) mod list.size(), for all values of i between 0 and list.size()-1, inclusive.Declaration − The java.util.Collections.rotate() is declared as follows -public static void rotate(List list, int distance)Let us see a program to rotate elements of a collection in Java -Example Live  Demoimport java.util.*; public class Example {    public static void main(String[] args) {   ... Read More

Elements can be filled in a long array using the java.util.Arrays.fill() method. This method assigns the required long value to the long array in Java. The two parameters required are the array name and the value that is to be stored in the array elements.A program that demonstrates this is given as follows -Example Live Demoimport java.util.Arrays; public class Demo {    public static void main(String[] argv) throws Exception {       long[] longArray = new long[5];       long longValue = 125;       Arrays.fill(longArray, longValue);       System.out.println("The long array content is: " + Arrays.toString(longArray)); ... Read More

In order to sort ArrayList in Descending order using Comparator, we need to use the Collections.reverseOrder() method which returns a comparator which gives the reverse of the natural ordering on a collection of objects that implement the Comparable interface.Declaration − The java.util.Collections.reverseOrder() method is declared as follows -public static Comparator reverseOrder()Let us see a program to sort an ArrayList in Descending order using Comparator  with Java Collections −Example Live Demoimport java.util.*; public class Example {    public static void main (String[] args) {       ArrayList list = new ArrayList();       list.add(10);       list.add(50);     ... Read More

The interfaces that are implemented by a class that is represented by an object can be determined using the java.lang.Class.getInterfaces() method. This method returns an array of all the interfaces that are implemented by the class.A program that demonstrates this is given as follows −Example Live Demopackage Test; import java.lang.*; import java.util.*; public class Demo {    public static void main(String[] args) {       listInterfaces(String.class);    }    public static void listInterfaces(Class c) {       System.out.println("The Class is: " + c.getName());       Class[] interfaces = c.getInterfaces();       System.out.println("The Interfaces are: " + Arrays.asList(interfaces)); ... Read More

In order to match the first name and last name using regular expression, we use the matches method in Java. The java.lang.String.matches() method returns a boolean value which depends on the matching of the String with the regular expression.Declaration −The java.lang.String.matches() method is declared as follows −public boolean matches(String regex)Let us see a program to validate the first name and last name with regular expressions −Example Live Demopublic class Example {    public static void main( String[] args ) {       System.out.println(firstName("Tom"));       System.out.println(lastName("hanks"));    }    // validate first name    public static boolean firstName( String ... Read More

The array type can be checked using the java.lang.Class.getComponentType() method. This method returns the class that represents the component type of the array. The array length can be obtained in int form using the method java.lang.reflect.Array.getLength().A program that demonstrates this is given as follows −Example Live Demoimport java.lang.reflect.Array; public class Demo {    public static void main (String args[]) {       int[] arr = {6, 1, 9, 3, 7};       Class c = arr.getClass();       if (c.isArray()) {          Class arrayType = c.getComponentType();          System.out.println("The array is of type: ... Read More