All the elements of a vector can be replaced by a specific element using java.util.Collections.fill() method. This method requires two parameters i.e. the Vector and the element that replaces all the elements in the Vector. No value is returned by the Collections.fill() method. A program that demonstrates this is given as follows:  Live Demo , The output of the above program is as foll.....

A single element in the Vector can be removed using the java.util.Vector.remove() method. This method removes the element at the specified index in the Vector. It returns the element that was removed. Also after the element is removed from the specified index, the rest of the Vector elements are shifted to the left. A program that demonstrates this is given as follows:  Live Demo , The.....

Elements can be added in the middle of a Vector by using the java.util.Vector.insertElementAt() method. This method has two parameters i.e. the element that is to be inserted in the Vector and the index at which it is to be inserted. If there is an element already present at the index specified by Vector.insertElementAt() then that element and all subsequent elements shift to the right by o.....

In Java concept of static class is introduced under concept of inner classes,which are specially designed for some delicate functionality in a class. Static class in Java are allowed only for inner classes which are defined under some other class,as static outer class is not allowed which means that we can't use static keyword with outer class. Static class are defined same as other inner.....

As we know that Hash map in Java does not maintain insertion order either by key or by order.Also it does not maintain any other order while adding entries to it. Now in order to sort a hash map according to the values mapped to its corresponding keys we first need to get all values of map considering that hash map has unique values only.Now put all the values in a list and sort this list .....

To send an e-mail using your Java Application is simple enough but to start with you should have JavaMail API and Java Activation Framework (JAF) installed on your machine. You can download latest version of JavaMail (Version 1.2) from Java's standard website. You can download latest version of JAF (Version 1.1.1) from Java's standard website. Download and unzip these files, in the new.....

As we know the primary role of the constructor is to instantiate a class object now if we made the constructor as private then we restrict its calling to be only in defining a class and not in some other class. Now the singleton class in Java is defined as the class which restricts the instantiation of a class and ensure that only one instance of the class exists in the JVM. After first ti.....

The java.util.PriorityQueue class is an unbounded priority queue based on a priority heap.Following are the important points about PriorityQueue − The elements of the priority queue are ordered according to their natural ordering, or by a Comparator provided at queue construction time, depending on which constructor is used. A priority queue does not permit null elements. A priorit.....

A Singleton pattern states that a class can have a single instance and multiple instances are not permitted to be created. For this purpose, we make the constructor of the class a private and return a instance via a static method. But using cloning, we can still create multiple instance of a class. See the example below − Live Demo , , Here you can see, we've created another .....

An immutable class object's properties cannot be modified after initialization. For example String is an immutable class in Java. We can create a immutable class by following the given rules below − Make class final − class should be final so that it cannot be extended. Make each field final − Each field should be final so that they cannot be modified after initializatio.....