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Java Articles
Page 320 of 450
How to find Date after 1 week in java 8?
The java.time package of Java provides API’s for dates, times, instances and durations. It provides various classes like Clock, LocalDate, LocalDateTime, LocalTime, MonthDay, Year, YearMonth etc. Using classes of this package you can get details related to date and time in much simpler way compared to previous alternatives.Java.time.LocalDate − This class represents a date object without time zone in ISO-8601 calendar system.The now() method of this class obtains the current date from the system clock.The plus() method of the LocalDate class accepts a long value representing the amount to add and an object of the interface TemporalAmount representing the unit ...
Read MoreWhat is InputMisMatchException in Java how do we handle it?
From Java 1.5 Scanner class was introduced. This class accepts a File, InputStream, Path and, String objects, reads all the primitive data types and Strings (from the given source) token by token using regular expressions.To read various datatypes from the source using the nextXXX() methods provided by this class namely, nextInt(), nextShort(), nextFloat(), nextLong(), nextBigDecimal(), nextBigInteger(), nextLong(), nextShort(), nextDouble(), nextByte(), nextFloat(), next().Whenever you take inputs from the user using a Scanner class. If the inputs passed doesn’t match the method or an InputMisMatchException is thrown. For example, if you reading an integer data using the nextInt() method and the value ...
Read MoreWhat changes has been introduced in JDK7 related to Exception handling in Java?
Since Java 7 try-with resources was introduced. In this we declare one or more resources in the try block and these will be closed automatically after the use. (at the end of the try block)The resources we declare in the try block should extend the java.lang.AutoCloseable class.ExampleFollowing program demonstrates the try-with-resources in Java.import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; public class FileCopying { public static void main(String[] args) { try(FileInputStream inS = new FileInputStream(new File("E:\Test\sample.txt")); FileOutputStream outS = new FileOutputStream(new File("E:\Test\duplicate.txt"))){ byte[] buffer = new byte[1024]; ...
Read MoreCan we cast reference variables in Java?
Java provides various datatypes to store various data values. It provides 7 primitive datatypes (stores single values) namely, boolean, byte, char, short, int, long, float, double and, reference datatypes (arrays and objects).Casting in JavaConverting one primitive data type into another is known as type casting.Exampleimport java.util.Scanner; public class TypeCastingExample { public static void main(String args[]){ Scanner sc = new Scanner(System.in); System.out.println("Enter an integer value: "); int i = sc.nextInt(); long num = i; System.out.println("Value of the given integer: "+num); } }OutputEnter an integer ...
Read MoreCan a method throw java.lang.Exception without declaring it in java?
No, for that matter to throw any exception explicitly you need to create an object of that exception and throw it using the throw keyword.Without creating an object you cannot throw an exception explicitly, you might create a scenario that causes the respective exception.ExampleFollowing Java program throws a NullPointerExceptionpublic class ExceptionExample { public static void main(String[] args) { System.out.println("Hello"); NullPointerException nullPointer = new NullPointerException(); throw nullPointer; } }OutputHello Exception in thread "main" java.lang.NullPointerException at MyPackage.ExceptionExample.main(ExceptionExample.java:6)
Read MoreHow to loop the program after an exception is thrown in java?
Read the inputs and perform the required calculations within a method. Keep the code that causes exception in try block and catch all the possible exceptions in catch block(s). In each catch block display the respective message and call the method again.ExampleIn the following example we have an array with 5 elements, we are accepting two integers from user representing positions in the array and performing division operation with them, if the integer entered representing the positions is more than 5 (length of the exception) an ArrayIndexOutOfBoundsException occurs and, if the position chosen for denominator is 4 which is 0 ...
Read MoreWhen do IllegalStateException and IllegalArgumentException get thrown? in java?
IllegalStateException:This exception is thrown when you call a method at illegal or inappropriate time an IlleagalStateException is generated.For example, the remove() method of the ArrayList class removes the last element after calling the next() or previous methods.After removing the element at the current position you need to move to the next element to remove it i.e. per one call of the next() method you can invoke this remove() method only once.Since the initial position of the list (pointer) will be before the first element, you cannot invoke this method without calling the next method.If you invoke the remove() method otherwise ...
Read MoreHandling IllegalComponentStateException in java.
It is the sub class of IllegalStateException, This indicates that AWT component is not in an appropriate state i.e. if you are working with components but, not using them properly leads to this exception. There are several scenarios where this exception occursExampleIn the following example we are trying to build a sample login form here after setting the visibility of the window to true, we are trying to set the location by platform true which is inappropriate.import java.awt.*; import java.awt.event.*; import javax.swing.*; public class LoginDemo extends JFrame implements ActionListener { JPanel panel; JLabel user_label, password_label, message; JTextField ...
Read MoreDifferent scenarios that cause NoSuchElementException in Java.
An exception is an issue (run time error) occurred during the execution of a program. When an exception occurs the program gets terminated abruptly and, the code past the line that generated the exception never gets executed. Each exception is represented by its respective class.NosuchElement ExceptionThis is a Runtime exception i.e. it occurs at the execution time.While accessing the contents of a collection, array or other objects using the accessor methods of an Enumeration, Iterator or, tokenizer, such as next() or nextElement(), if you try to get the elements from an empty object, or if you try to get the ...
Read MoreHow to create an immutable set in Java?
Whenever you need to create an object which cannot be changed after initialization you can define an immutable object. There are no specific rules to create immutable objects, the idea is to restrict the access of the fields of a class after initialization.A Set is an interface in collection framework, which does not allow duplicate values.You need to keep following points in mind while creating an immutable set −We should not be able to add or delete elements from it.we should not be able to add null values to an immutable set.Once you create an immutable set you cannot add ...
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