In Java, serialization is a concept using which we can write the state of an object into a byte stream so that we can transfer it over the network (using technologies like JPA and RMI).To serialize an object −Make sure the class implements the Serializable interface.Create a FileOutputStream object representing the file (abstract path) of the file to which the object is to be stored.Create a ObjectOutputStream object by passing the above created FileOutputStream object.Write the object to the file using the writeObject() method.To de-serialize an objectCreate a FileInputStream object representing the file that contains the serialized object.Read the object ... Read More

A collection object in Java is the one which stores references of other objects in it. The java.util package provides the classes and interfaces for collections. There are four main collection interfaces namely Set Lists, Queues, Maps.Set − The set object is a collection which stores group of elements, it grows dynamically and it does not allow duplicate elements.HashSet and LinkedHashSet are the classes that implements Set interface. You can create a Set object by implementing either of these classes.Exampleimport java.util.HashSet; public class SetExample {    public static void main(String args[]) {       //Instantiating the HashSet       ... Read More

An array is a data structure/container/objectthat stores a fixed-size sequential collection of elements of the same type. The size/length of the array is determined at the time of creation.The position of the elements in the array is called as index or subscript. The first element of the array is stored at the index 0 and, the second element is at the index 1 and so on.Each element in an array is accessed using an expression which contains the name of the array followed by the index of the required element in square brackets.For example, if an array of 6 elements ... Read More

If a single number is missing in an integer array that contains a sequence of numbers values, you can find it basing of the sum of numbers or, basing on the xor of the numbers.Based on the sum of the numbers −The sum of n sequential numbers will be [n*(n+1)]/2. Using this get the sum of the numbers the n numbers.Add all the elements in the array.Subtract the sum of the numbers in the array from the sum of the n numbers.Exampleimport java.util.Scanner; public class MissingNumber {    public static void main(String[] args) {       Scanner sc = ... Read More

To find the first non-repeating number in an array −Construct count array to store count of each element in the given array with same length and with initial value 0 for all elements.Compare each element in the array with all other elements, except itself.If match occurs increment its value in the count array.Get the index of the first 0 in the count array and print the element in the input array at this index.Exampleimport java.util.Arrays; public class NonRpeatingArray {    public static void main(String args[]) {       int array[] = {114, 225, 669, 996, 336, 6547, 669, 225, ... Read More

To find the first non-repeating number in an array −Construct count array to store count of each element in the given array with same length and with initial value 0 for all elements.Compare each element in the array with all other elements, except itself.If match occurs increment its value in the count array.Get the index of the first non-zero element in the count array and print the element in the input array at this index.Exampleimport java.util.Arrays; public class NonRpeatingArray {    public static void main(String args[]) {       int array[] = {114, 225, 669, 996, 336, 6547, 669, ... Read More

The fillInStackTrace() is an important method of Throwable class in Java. The stack trace can be useful to determine where exactly the exception is thrown. There may be some situations where we need to rethrow an exception and find out where it is rethrown, we can use the fillInStackTrace() method in such scenarios. Syntax public Throwable fillInStackTrace() Example public class FillInStackTraceTest { public static void method1() throws Exception { throw new Exception("This is thrown from method1()"); } public static void method2() throws Throwable { try { ... Read More

In general, arrays are the containers that store multiple variables of the same datatype. These are of fixed size and the size is determined at the time of creation. Each element in an array is positioned by a number starting from 0.You can access the elements of an array using name and position as −System.out.println(myArray[3]); //Which is 1457Creating an array in JavaIn Java, arrays are treated as referenced types you can create an array using the new keyword similar to objects and populate it using the indices as −int myArray[] = new int[7];While creating array in this way, you must specify ... Read More

In general, arrays are the containers that store multiple variables of the same datatype. These are of fixed size and the size is determined at the time of creation. Each element in an array is positioned by a number starting from 0.You can access the elements of an array using name and position as −System.out.println(myArray[3]); //Which is 1457Creating an array in JavaIn Java, arrays are treated as referenced types you can create an array using the new keyword similar to objects and populate it using the indices as −int myArray[] = new int[7];While creating array in this way, you must ... Read More

An array is a data structure/container/object that stores a fixed-size sequential collection of elements of the same type. The size/length of the array is determined at the time of creation.The position of the elements in the array is called as index or subscript. The first element of the array is stored at the index 0 and, the second element is at the index 1 and so on.Each element in an array is accessed using an expression which contains the name of the array followed by the index of the required element in square brackets.For example, if an array of 6 elements ... Read More