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You can declare an array just like a variable −int myArray[];You can create an array just like an object using the new keyword −myArray = new int[5];You can initialize the array by assigning values to all the elements one by one using the index −myArray [0] = 101; myArray [1] = 102;You can access the array element using the index values −System.out.println("The first element of the array is: " + myArray [0]); System.out.println("The first element of the array is: " + myArray [1]); Alternatively, you can create and initialize an array using the flower braces ({ }): Int [] myArray = {10, 20, 30, 40, 50}
A checked exception is an exception that occurs at the compile time, these are also called as compile time exceptions. These exceptions cannot simply be ignored at the time of compilation; the programmer should take care of (handle) these exceptions.ExampleIf you use FileReader class in your program to read data from a file, if the file specified in its constructor doesn't exist, then a FileNotFoundException occurs, and the compiler prompts the programmer to handle the exception.import java.io.File; import java.io.FileReader; public class FilenotFound_Demo { public static void main(String args[]) { File file = new File("E://file.txt"); ... Read More
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, and the syntax for using try/catch looks like the following –Syntaxtry { // Protected code } catch (ExceptionName e1) { // Catch block }The code which is prone to exceptions is placed in the try block. When an exception raised inside a try block, instead of terminating the program JVM stores the exception details in the exception stack and proceeds to the catch block.
A catch statement involves declaring the type of exception you are trying to catch. If an exception occurs in the try block, the catch block (or blocks) that follows the try is checked. If the type of exception that occurred is listed in a catch block, the exception is passed to the catch block much as an argument is passed into a method parameter.Exampleimport java.io.File; import java.io.FileInputStream; public class Test { public static void main(String args[]) { System.out.println("Hello"); try { File file = new File("my_file"); ... Read More
The java.io package contains nearly every class you might ever need to perform input and output (I/O) in Java. All these streams represent an input source and an output destination. The stream in the java.io package supports many data such as primitives, object, localized characters, etc.A stream can be defined as a sequence of data. There are two kinds of Streams −InputStream: The InputStream is used to read data from a source.OutputStream: The OutputStream is used for writing data to a destination.As described earlier, a stream can be defined as a sequence of data. The InputStream is used to read data from ... Read More
After a serialized object has been written into a file, it can be read from the file and Deserialized that is, the type information and bytes that represent the object and its data can be used to recreate the object in memory.Exampleimport java.io.*; public class DeserializeDemo { public static void main(String [] args) { Employee e = null; try { FileInputStream fileIn = new FileInputStream("/tmp/employee.ser"); ObjectInputStream in = new ObjectInputStream(fileIn); e = (Employee) in.readObject(); in.close(); ... Read More
Serialization Java provides a mechanism, called object serialization where an object can be represented as a sequence of bytes that includes the object's data as well as information about the object's type and the types of data stored in the object.Exampleimport java.io.*; public class SerializeDemo { public static void main(String [] args) { Employee e = new Employee(); e.name = "Reyan Ali"; e.address = "Phokka Kuan, Ambehta Peer"; e.SSN = 11122333; e.number = 101; try { ... Read More
File class provides various methods to perform respective file operations.canRead(): This method tests whether the application can read the file denoted by this abstract pathname. It returns true if and only if the file specified by this abstract pathname exists and can be read by the application; false otherwise.canWrite(): This method tests whether the application can modify the file denoted by this abstract pathname. It returns true if and only if the file system actually contains a file denoted by this abstract pathname and the application is allowed to write to the file; false otherwise.createNewFile(): This method atomically creates a ... Read More
While creating a thread class we must override the run() method of the Thread class. This method provides an entry point for the thread and you will put your complete business logic inside this method.Exampleclass ThreadDemo extends Thread { private String threadName; ThreadDemo( String name) { threadName = name; System.out.println("Creating " + threadName ); } public void run() { System.out.println("Running " + threadName ); try { for(int i = 4; i ... Read More
The remove(int index) method of the java.util.ArrayList class removes the element at the specified position in this list. Shifts any subsequent elements to the left (subtracts one from their indices).Exampleimport java.util.ArrayList; public class ArrayListDemo { public static void main(String[] args) { ArrayList arrlist = new ArrayList(5); arrlist.add(20); arrlist.add(15); arrlist.add(30); arrlist.add(45); System.out.println("Size of list: " + arrlist.size()); for (Integer number : arrlist) { System.out.println("Number = " + number); } ... Read More