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Articles by Maruthi Krishna
Page 20 of 50
Why TreeSet Does not allow null values in Java?
TreeSet provides an implementation of the Set interface that uses a tree for storage. Objects are stored in a sorted and ascending order.Access and retrieval times are quite fast, which makes TreeSet an excellent choice when storing large amounts of sorted information that must be found quickly.The reason is, if you look at the internal implementation of the TreeSet, it uses natural ordering, that means TreeSet uses Comparable interface by default to sort its value by comparing other value.Examplepublic class TreeSetDemo { public static void main(String args[]) { TreeSet treeSet = new TreeSet(); ...
Read MoreHow to convert an array to Set and vice versa in Java?
Array is a container which can hold a fix number of entities, which are of the same type. Each entity of an array is known as element and, the position of each element is indicated by an integer (starting from 0) value known as index.Exampleimport java.util.Arrays; public class ArrayExample { public static void main(String args[]) { Number integerArray[] = new Integer[3]; integerArray[0] = 25; integerArray[1] = 32; integerArray[2] = 56; System.out.println(Arrays.toString(integerArray)); } }Output[25, 32, 56]Whereas a Set object is a collection (object) stores ...
Read MoreIs 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 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[]) { ...
Read MoreWhen does a Java Array Throws 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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