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Java Articles
Page 130 of 450
Java public static void main(String[] args)
The Java program starts execution when the JVM calls the main() method. A Java application begins with this method. Without a main() method, a Java file will compile successfully because at compile time, the compiler doesn't check for a main method, but at run time JVM checks whether the main() method is available or not. Therefore, we will get an exception at run time. In this article, we will understand why we follow the convention "public static void main(String[] args)." The Syntax of a basic Java program looks like: public class class_name { // This line must be ...
Read MoreJava Program to Calculate difference between two Time Periods
We are given two time periods, and our task is to write a Java program to calculate the difference between them. For this problem, we can use classes and methods of java.time, java.util, and java.text packages. SimpleDateFormat class Date class LocalDate class Period class parse() method between() method As we move further in this article, we will understand the uses of these classes and methods in calculating the difference between two time periods. Some examples ...
Read MoreJava Program to Check Whether a Number can be Expressed as Sum of Two Prime Numbers
The given task is to write a Java program to check if an integer can be expressed as the sum of two prime numbers. A number is said to be a prime if it has only two factors, which are 1 and itself, and cannot be divided by any other number. Some examples of prime numbers are 2, 3, 5, 7, 11, 13, and so on. 2 is the only even prime number; all other prime numbers are odd numbers. Example Scenario Let's understand the problem with an example. The possible solution is 43 = 2 + 41. Here, 2 and ...
Read MoreJava Nested Loops with Examples
Loops in Java are called control statements because they decide the flow of execution of a program based on some condition. Java allows the nesting of loops. When we put a loop within another loop, then we call it a nested loop. Nested loops are used when we need to iterate through a matrix array and when we need to do any pattern-based questions. In this article, we are going to learn about Java nested loops with examples. Nested Loops in Java We can create nested loops for the following control statements in Java: ...
Read MoreJava Program to Reverse a Number
For a given input number, write a Java program to reverse its digits. In reverse operation, we print the digits of given number from the last to start. The digit at the last position is swapped with the digit at the first position, the second last digit is swapped with second position digit and so on. Example Scenario: Input: number = 123456; Output: rev_number: 654321 How to Reverse a Number in Java? There are multiple ways to reverse the digits of a given number. We are going to discuss the following: Using ...
Read MoreHow to print the elements of a HashMap in Java?
In Java, a HashMap is a subclass of the AbstractMap class and is used to store key-value pairs. Each key in the map is mapped to a single value in the map, and the keys are unique.Printing Java HashMap Elements We can insert a key only once in a map, and duplicate keys are not allowed, but the value can be mapped to multiple keys. We can add the elements using the put() method of the HashMap class and iterate over the elements using the Iterator interface. Java HashMap provides various ways to print its elements as follows: ...
Read MoreWhat are the uses of generic collections in Java?
What are Generic Collections in Java? In Java, the Generic collections were introduced in Java 5. These collections disable the type-casting, and there is no need for explicit type-casting if we use generic collections. The generic collections are type-safe and detect type-related errors at compile time. It allows the datatypes to pass as parameters to classes or interfaces. The Compiler is responsible for checking the compatibility of the types. Syntax Following is the way to create generic collections in Java: class or interface Where type specifies the type of the object, such as: Integer, String, Character, etc.. You can create generic ...
Read MoreImportance of @Override annotation in Java?
What is an Annotation? An annotation is like metadata that provides additional information about the code. It does not affect the code directly but provides the information so that the compiler or runtime environment can use it while executing the code. To define or use any annotation in Java, you need to specify the annotation name starting with the "@" symbol. Here is the syntax to use annotations in Java: @annotation_name Where the @ symbol specifies the annotation, and annotation_name is the name of the annotation. Following is a list of a few important annotations and their usage: ...
Read MoreJava program to print left triangle star pattern
In this article, we will understand how to print the left triangle star pattern in Java. This pattern is also known as the Mirrored Right Triangle Star pattern. Below is a demonstration of the same- Input: Number of rows: 6 Output: * * * * * * * * * * * * * * * * * * * * * Printing Left Triangle Star Pattern Following are the ...
Read MoreJava program to find sum of N numbers using recursion
In this article, we will learn how to find the sum of N numbers using recursion in Java. Recursion is when a method calls itself repeatedly until a base condition is met. In Java, each recursive call is placed on the stack until the base case is reached, after which values are returned to calculate the result. To solve with recursion, we need to divide our problem into smaller chunks, then find out solution for that smaller part, and that will be our base condition. In this problem, to find the sum of N numbers using recursion, we can store ...
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