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Java Articles
Page 296 of 450
Is there any way to skip finally block even if some exception occurs in exception block using java?
An exception is an issue (run time error) occurred during the execution of a program. When an exception occurred the program gets terminated abruptly and, the code past the line that generated the exception never gets executed.Try, catch, finally blocksTo handle exceptions Java provides a try-catch block mechanism.A try/catch block is placed around the code that might generate an exception. Code within a try/catch block is referred to as protected code.Syntaxtry { // Protected code } catch (ExceptionName e1) { // Catch block }When an exception raised inside a try block, instead of terminating the program JVM stores ...
Read MoreIs it possible to resume java execution after exception occurs?
An exception is an issue (run time error) occurred during the execution of a program. When an exception occurred the program gets terminated abruptly and, the code past the line that generated the exception never gets executed.There are two types of exceptions in Java.Unchecked Exception − An unchecked exception is the one which occurs at the time of execution. These are also called as Runtime Exceptions. These include programming bugs, such as logic errors or improper use of an API. Runtime exceptions are ignored at the time of compilation.Checked Exception − A checked exception is an exception that occurs at ...
Read MoreHow can we decide that custom exception should be checked or unchecked in java?
An exception is an issue (run time error) occurred during the execution of a program. When an exception occurred the program gets terminated abruptly and, the code past the line that generated the exception never gets executed.User defined exceptionsYou can create your own exceptions in Java and they are known as user defined exceptions or custom exceptions.To create a user defined exception extend one of the above mentioned classes. To display the message override the toString() method or, call the superclass parameterized constructor by passing the message in String format.MyException(String msg){ super(msg); } Or, public String toString(){ return ...
Read MoreHow does a ClassLoader work in Java?
A Java Class is stored in the form of byte code in a .class file after it is compiled. The ClassLoader loads the class of the Java program into memory when it is required. The ClassLoader is hierarchical and so if there is a request to load a class, it is delegated to the parent class loader.The types of ClassLoader in Java are given as followsBootstrap ClassLoaderExtensions ClassLoaderSystem ClassLoaderExamplepublic class ClassLoaderTest { public static void main(String[] args) { System.out.println("class loader for this class: " + ClassLoaderTest.class.getClassLoader()); System.out.println("class loader for DNSNameService: " + sun.net.spi.nameservice.dns.DNSNameService.class.getClassLoader()); ...
Read MoreCan we have an empty catch block in Java?
Yes, we can have an empty catch block. But this is a bad practice to implement in Java.Generally, the try block has the code which is capable of producing exceptions, if anything wrong in the try block, for instance, divide by zero, file not found, etc. It will generate an exception that is caught by the catch block. The catch block catches and handles the exception. If the catch block is empty then we will have no idea what went wrong within our code.Examplepublic class EmptyCatchBlockTest { public static void main(String[] args) { try { int a ...
Read MoreHow can we disable the leaf of JTree in Java?
A JTree is a component that presents a hierarchical view of data. The user has the ability to expand or collapse individual sub-trees. A TreeNode interface defines the methods that must be implemented nodes of a JTree object. The DefaulMutableTreeNode class provides a default implementation of a TreeNode interface. We can disable the leaf of JTree by overriding the getTreeCellRendererComponent() method of DefaultTreeCellRenderer class.Syntaxpublic Component getTreeCellRendererComponent(JTree tree, Object value, boolean sel, boolean expanded, boolean leaf, int row, boolean hasFocus)Exampleimport java.awt.*; import javax.swing.tree.*; import javax.swing.*; public class JTreeLeafNodeDisableTest extends JFrame { private TreeNode treeNode; private JTree tree; public JTreeLeafNodeDisableTest() { setTitle("JTreeLeafNodeDisable Test"); ...
Read MoreHow to print custom message instead of ErrorStackTrace in java?
An exception is an issue (run time error) occurred during the execution of a program. When an exception occurred the program gets terminated abruptly and, the code past the line that generated the exception never gets executed.Printing the Exception messageYou can print the exception message in Java using one of the following methods which are inherited from Throwable class.printStackTrace() − This method prints the backtrace to the standard error stream.getMessage() − This method returns the detail message string of the current throwable object.toString() − This message prints the short description of the current throwable object.Exampleimport java.util.Scanner; public class PrintingExceptionMessage { ...
Read MoreWhat is the difference between throw e and throw new Exception(e) in catch block in java?
An exception is an issue (run time error) occurred during the execution of a program. Here are some example scenarios −If you have an array of size 10 if a line in your code tries to access the 11th element in this array.If you are trying to divide a number with 0 which (results to infinity and JVM doesn’t understand how to valuate it).When exception occurs the program terminates abruptly at the line that caused exception, leaving the remaining part of the program unexecuted. To prevent this, you need to handle exceptions.There are two types of exceptions in java.Unchecked Exception ...
Read MoreHow IllegalArgumentException automatically handled inside 'if' condition in java?
Whenever you pass inappropriate arguments to a method or constructor, an IllegalArgumentException is thrown. It is a Runtime exception therefore there is no need to handle this at the time of compilation.ExampleThe valueOf() method of the java.sql.Date class accepts a String representing a date in JDBC escape format yyyy-[m]m-[d]d and converts it into a java.sql.Date object.import java.sql.Date; import java.util.Scanner; public class IllegalArgumentExample { public static void main(String args[]) { Scanner sc = new Scanner(System.in); System.out.println("Enter your date of birth in JDBC escape format (yyyy-mm-dd) "); String dateString = sc.next(); ...
Read MoreWhy can I throw null in Java and why does it upcast to a NullPointerException?
In Java there is default value for every type, when you don’t initialize the instance variables of a class Java compiler initializes them on your be-half with these values. Null is the default value of the object type, you can also manually assign null to objects in a method.Object obj = null;But, you cannot use an object with null value or (a null value instead of an object) if you do so, a NullPointerException will be thrown.Examplepublic class Demo { String name = "Krishna"; int age = 25; public static void main(String args[]) { ...
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