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Java Articles
Page 447 of 450
What is meant by Java being an architecture neutral language?
Unlike many other programming languages including C and C++, when Java is compiled, it is not compiled into platform specific machine, rather into platform-independent byte code. This byte code is distributed over the web and interpreted by the Virtual Machine (JVM) on whichever platform it is being run on. Thus when you write a piece of Java code in a particular platform and generated an executable code .class file. You can execute/run this .class file on any system the only condition is that the target system should have JVM (JRE) installed in it. In short, Java compiler generates an architecture-neutral ...
Read MoreWhat does import Java.util.* in Java do?
Java util package contains collection framework, collection classes, classes related to date and time, event model, internationalization, and miscellaneous utility classes. On importing this package, you can access all these classes and methods.Following table lists out the classes in the collection package.InterfacesDescriptionClassesCollectionCollection Interface represents a group of objects. It is a root interface of collection framework.Abstract CollectionSetIt is a dynamic group of unique elements. It does not store duplicate element.HashSetLinkedHashSetListThey are similar to sets with the only difference that they allow duplicate values in them.StackvectorArrayListLinkedListQueueIt is an arrangement of the type First-In-First-Out (FIFO).First element put in the queue is the ...
Read MoreCan a method return multiple values in Java?
You can return only one value in Java. If needed you can return multiple values using array or an object. Example In the example given below the calculate() method accepts two integer variables performs the addition subtraction, multiplication and, division operations on them stores the results in an array and returns the array. public class ReturningMultipleValues { static int[] calculate(int a, int b){ int[] result = new int[4]; result[0] = a + b; result[1] = a - b; ...
Read MoreWhy the main method has to be in a java class?
Main method is the entry point of the execution in Java. When we execute a class JVM searches for the main method and execute the contents of it line by line. If you observe the following example you can compile a this program but if you try to execute it you will get an error saying “Main method not found”. Example abstract class SuperTest { public abstract void sample(); public abstract void demo(); } public class Example extends SuperTest{ public void sample(){ System.out.println("sample method ...
Read MoreHow do I write package names in Java?
While choosing a package name you need to keep the following points in mind. The name of the package should be in small letters. It is suggested to start the name of the package with the top level domain level followed by sub domains, ex: com.example.tutorialspoint. Example You can declare a package as in. package com.mypackage.tutorialspoint; Public class Sample { Public static void main(String args[]) { System.out.println("Welcome to Tutorialspoint"); } } Executing a package You need to compile the file with packages using –d ...
Read MoreHow to add items to an array in java dynamically?
Since the size of an array is fixed you cannot add elements to it dynamically. But, if you still want to do it then, Convert the array to ArrayList object.Add the required element to the array list.Convert the Array list to array.Exampleimport java.util.ArrayList; import java.util.Arrays; import java.util.Scanner; public class AddingItemsDynamically { public static void main(String args[]) { Scanner sc = new Scanner(System.in); System.out.println("Enter the size of the array :: "); int size = sc.nextInt(); String myArray[] = new String[size]; System.out.println("Enter elements of the array ...
Read MoreHow to convert BLOB to Byte Array in java?
You can contents of a blob into a byte array using the getBytes() method.Exampleimport java.awt.Image; import java.awt.image.BufferedImage; import java.sql.Blob; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; import java.util.Arrays; public class BlobToByteArray { public static void main(String[] args) throws Exception { Image image = new BufferedImage(300, 400, BufferedImage.TYPE_INT_RGB); String JDBC_DRIVER = "com.mysql.jdbc.Driver"; String DB_URL = "jdbc:mysql://localhost/mydb"; String USER = "root"; String PASS = "password"; ...
Read MoreHow to access the members of a class from another class in Java?
To access the members of a class from other class. First of all, import the class. Create an object of that class. Using this object access, the members of that class. Suppose there is a class in a package called myPackage with a method named display() package myPackage; public class Sample { public void display() { System.out.println("Hello"); } } You can access it as. import myPackage; public class MyClass { public static void main(String args[]) { Sample s = new Sample(); s.done(); } } Output hello
Read MoreAre the private variables and private methods of a parent class inherited by the child class in Java?
No, a child class can’t inherit private members of the parent class, it can inherit only protected, default, and public members of it. If you try it gives you a compile time error as: − Example class Super{ private int data = 30; public void display(){ System.out.println("Hello this is the method of the super class"); } } public class Sub extends Super{ public void greet(){ System.out.println("Hello this is the method of the sub class"); ...
Read MoreHow to convert Java Array/Collection to JSON array?
Google provides a library named org.json.JSONArray and, following is the maven dependency to add library to your project. com.googlecode.json-simple json-simple 1.1 The JSONArray class of the org.json package provides put() method. Using this method, you can populate the JSONArray object with the contents of the elements.Exampleimport org.json.JSONArray; public class ArrayToJson { public static void main(String args[]) { String [] myArray = {"JavaFX", "HBase", "JOGL", "WebGL"}; JSONArray jsArray = new JSONArray(); ...
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