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Java Articles
Page 121 of 450
Difference between HashMap and HashSet in Java.
HashMap and HashSet both are one of the most important classes of Java Collection framework.Following are the important differences between HashMap and HashSet.Sr. No.KeyHashMapHashSet1ImplementationHashmap is the implementation of Map interface.Hashset on other hand is the implementation of set interface.2Internal implementationHashmap internally do not implements hashset or any set for its implementation.Hashset internally uses Hashmap for its implementation.3Storage of elementsHashMap Stores elements in form of key-value pair i.e each element has its corresponding key which is required for its retrieval during iteration.HashSet stores only objects no such key value pairs maintained.4Method to add elementPut method of hash map is used to ...
Read MoreJava Program to count letters in a String
Let’s say we have the following string, that has some letters and numbers.String str = "9as78";Now loop through the length of this string and use the Character.isLetter() method. Within that, use the charAt() method to check for each character/ number in the string.for (int i = 0; i < str.length(); i++) { if (Character.isLetter(str.charAt(i))) count++; }We have set a count variable above to get the length of the letters in the string.Here’s the complete example.Examplepublic class Demo { public static void main(String []args) { String str = "9as78"; int count = ...
Read MoreHow to create date object in Java?
Using the Date classYou can create a Date object using the Date() constructor of java.util.Date constructor as shown in the following example. The object created using this constructor represents the current time.Exampleimport java.util.Date; public class CreateDate { public static void main(String args[]) { Date date = new Date(); System.out.print(date); } }OutputThu Nov 02 15:43:01 IST 2018Using the SimpleDateFormat classUsing the SimpleDateFormat class and the parse() method of this you can parse a date string in the required format and create a Date object representing the specified date.Exampleimport java.text.ParseException; import java.text.SimpleDateFormat; ...
Read MoreMultiple inheritance by Interface in Java
An interface contains variables and methods like a class but the methods in an interface are abstract by default unlike a class. Multiple inheritance by interface occurs if a class implements multiple interfaces or also if an interface itself extends multiple interfaces.A program that demonstrates multiple inheritance by interface in Java is given as follows:Exampleinterface AnimalEat { void eat(); } interface AnimalTravel { void travel(); } class Animal implements AnimalEat, AnimalTravel { public void eat() { System.out.println("Animal is eating"); } public void travel() { System.out.println("Animal is travelling"); } ...
Read MoreJava program for Multiplication of Array elements
To find the product of elements of an array.create an empty variable. (product)Initialize it with 1.In a loop traverse through each element (or get each element from user) multiply each element to product.Print the product.Exampleimport java.util.Arrays; import java.util.Scanner; public class ProductOfArrayOfElements { public static void main(String args[]){ System.out.println("Enter the required size of the array :: "); Scanner s = new Scanner(System.in); int size = s.nextInt(); int myArray[] = new int [size]; int product = 1; System.out.println("Enter the elements of the array one by one "); for(int i=0; i
Read MoreSplit String with Comma (,) in Java
Let’s say the following is our string.String str = " This is demo text, and demo line!";To split a string with comma, use the split() method in Java.str.split("[,]", 0);The following is the complete example.Examplepublic class Demo { public static void main(String[] args) { String str = "This is demo text, and demo line!"; String[] res = str.split("[,]", 0); for(String myStr: res) { System.out.println(myStr); } } }OutputThis is demo text and demo line!
Read MoreConcatenate string to an int value in Java
To concatenate a string to an int value, use the concatenation operator.Here is our int.int val = 3;Now, to concatenate a string, you need to declare a string and use the + operator.String str = "Demo" + val;Let us now see another example.Exampleimport java.util.Random; public class Demo { public static void main( String args[] ) { int val = 3; String str = "" + val; System.out.println(str + " = Rank "); } }Output3 = Rank
Read MoreJava Program to convert ASCII code to String
To convert ASCII to string, use the toString() method. Using this method will return the associated character.Let’s say we have the following int value, which works as ASCII for us.int asciiVal = 89;Now, use the toString() method.String str = new Character((char) asciiVal).toString();Examplepublic class Demo { public static void main(String []args) { int asciiVal = 87; String str = new Character((char) asciiVal).toString(); System.out.println(str); } }OutputW
Read MoreGenerate a random array of integers in Java
In order to generate random array of integers in Java, we use the nextInt() method of the java.util.Random class. This returns the next random integer value from this random number generator sequence.Declaration − The java.util.Random.nextInt() method is declared as follows −public int nextInt()Let us see a program to generate a random array of integers in Java −Exampleimport java.util.Random; public class Example { public static void main(String[] args) { Random rd = new Random(); // creating Random object int[] arr = new int[5]; for (int i = 0; i
Read MorePrint a 2D Array or Matrix in Java
In this post we will try to print an array or matrix of numbers at console in same manner as we generally write on paper.For this the logic is to access each element of array one by one and make them print separated by a space and when row get to end in matrix then we will also change the row.Examplepublic class Print2DArray { public static void main(String[] args) { final int[][] matrix = { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } }; for (int i = 0; i
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