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Articles by Maruthi Krishna
Page 10 of 50
How to insert an object in an ArrayList at a specific position in java?
The add() method of the ArrayList class helps you to add elements to an array list. It has two variants −add(E e) − This method accepts an object/elements as a parameter and adds the given element at the end of the list.public void add(int index, E element) − This method accepts an element and an integer value representing the position at which we need to insert it and inserts the specified element at the specified position in this list. Shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices).Therefore ...
Read MoreHow to avoid ConcurrentModificationException while iterating a collection in java?
When you are working with collection objects, while one thread is iterating over a particular collection object, if you try to add or remove elements from it, a ConcurrentModificationException will be thrown.Not only that, If you are iterating a collection object, add or remove elements to it and try to iterate its contents again it is considered that you are trying to access the collection object using multiple threads and ConcurrentModificationException is thrown.Exampleimport java.util.ArrayList; import java.util.Iterator; public class OccurenceOfElements { public static void main(String args[]) { ArrayList list = new ArrayList(); //Instantiating ...
Read MoreWhat is ArrayStoreException in Java?
When you have created an array of a particular data type with fixed size and populate it if you store a value other than its datatype an ArrayStoreException is thrown at the run time.ExampleIn the following Java program, we are creating an Integer array and trying to store a double value in it.import java.util.Arrays; public class ArrayStoreExceptionExample { public static void main(String args[]) { Number integerArray[] = new Integer[3]; integerArray[0] = 12548; integerArray[1] = 36987; integerArray[2] = 555.50; integerArray[3] = 12548; ...
Read MoreWhat is meant by re-throwing exceptions in Java?
When an exception is cached in a catch block, you can re-throw it using the throw keyword (which is used to throw the exception objects).While re-throwing exceptions you can throw the same exception as it is without adjusting it as −try { int result = (arr[a])/(arr[b]); System.out.println("Result of "+arr[a]+"/"+arr[b]+": "+result); } catch(ArithmeticException e) { throw e; }Or, wrap it within a new exception and throw it. When you wrap a cached exception within another exception and throw it, it is known as exception chaining or, exception wrapping, by doing this you can adjust your exception, throwing a ...
Read MoreHow to move files using FileUtils in Java?
Using the File classThe class named File of the java.io package represents a file or directory (pathnames) in the system. This class provides various methods to perform various operations on files/directories.This class provides various methods to manipulate files, The rename() method of the File class accepts a String representing a destination file and, renames the abstract file path of the current file to the given one.This method actually moves the file from the source path to the destination path.Exampleimport java.io.File; public class MovingFile { public static void main(String args[]) { //Creating a source file object ...
Read MoreWhat are variable arguments in java?
While defining a method, In general, we will specify the arguments it accepts along with the type as −myMethod(int a, String b){ }Suppose if you need to accept more than one variable of the same type you need to specify the variables one after the other as −myMethod(int a, int b, int c){ }You can also pass a variable number of arguments of a particular type, to a method. These are known as variable arguments or, varargs. They are represented by three dots (…)Syntaxpublic myMethod(int ... a) { // method body }Once you use variable arguments as a parameter ...
Read MoreBufferedReader class in Java.
The BufferedReader class of Java is used to read the stream of characters from the specified source (character-input stream). The constructor of this class accepts an InputStream object as a parameter.This class provides a method named read() and readLine() which reads and returns the character and next line from the source (respectively) and returns them.Instantiate an InputStreamReader class bypassing your InputStream object as a parameter.Then, create a BufferedReader, bypassing the above obtained InputStreamReader object as a parameter.Now, read data from the current reader as String using the readLine() or read() method.ExampleThe following Java program demonstrates how to read integer data ...
Read MoreIn how many ways we can convert a String to a character array using Java?
You can convert a String to a character array either by copying each element of the String to an array or, using the toCharArray() method.Copying each elementGet the String to be converted.Create an empty character array with the length of the String.The charAt() method of the String class returns the character at a particular position. Using this method copy each character of the String to the array.Exampleimport java.util.Arrays; import java.util.Scanner; public class StringToCharArray { public static void main(String args[]) { Scanner sc = new Scanner(System.in); System.out.println("Enter a String value: "); ...
Read MoreHow to get Exception log from a console and write it to external file in java?
There are several logging frame works available to log your data in to files. You can also define your own method.Example − Using I/O packageFollowing Java program has an array storing 5 integer values, we are letting the user to choose two elements from the array (indices of the elements) and performing division between them. We are wrapping this code in try block with three catch blocks catching ArithmeticException, InputMismatchException and, ArrayIndexOutOfBoundsException. In each of them we are invoking the writeToFile() method.This method accepts an exception object, and appends it to a file using the write() method of the Files ...
Read MoreCan we to override a catch block in java?
DescriptionWhen a piece of code in particular method throws an exception, and is handled using try-catch pair. If we are calling this method from another one and, the calling line is wrapped within try-catch pair. Now, how can I override the catch block by the catch block of the calling method.When a piece of code in a method throws an exception (compile time) we must either handle it by wrapping it within the try-catch pair or, throw it (postpone) to the calling method using the throws keyword else a compile time error occurs.In the following Java example the code in ...
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