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Java Articles
Page 444 of 450
How do I write variable names in Java?
While choosing an identifier to declare a variable in Java you need to keep the following points in mind. The name of the variable should begin with either alphabet or, an underscore (_) or, a dollar ($) sign. The identifiers used for variables must not be keywords. No spaces or special characters are allowed in the variable names of Java. Variable names may contain 0 to 9 numbers (if not at the beginning). Variable names are case sensitive i.e. MY_NUM is different from my_num. If you use two words in a identifier then the you should follow camel case ...
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 interface names in Java?
While writing an interface/class names you need to keep the following points in mind. First letter of the interface/class name should be capital and remaining letters should be small (mixed case). interface Sample Likewise, first letter of each word in the name should be capital an remaining letters should be small. interface MYInterface Keeping interface names simple and descriptive is suggestable. Better not to use acronyms while writing interface/class names. Example Live Demo interface MyInterface { void sample(); void demo(); } ...
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 do I write constants names in Java?
While writing the name of the constants it is suggested to write all the letters in upper case. If constant contains more than one word they should be separated by underscore (_). Example Live Demo public class ConstantsTest { public static final int MIN_VALUE = 22; public static final int MAX_VALUE = 222; public static void main(String args[]) { System.out.println("Value of the constant MIN_VALUE: "+MIN_VALUE); System.out.println("Value of the constant MAX_VALUE: "+MAX_VALUE); } } Output Value of the constant MIN_VALUE: 22 Value of the constant MAX_VALUE: 222
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 convert a byte array to a hex string in Java?
The printHexBinary() method of the DatatypeConverter class accepts a byte array and returns a hex string.Exampleimport javax.xml.bind.DatatypeConverter; public class ByteToHexString { public static void main(String args[]) { String sam = "Hello how are you how do you do"; byte[] byteArray = sam.getBytes(); String hex = DatatypeConverter.printHexBinary(byteArray); System.out.println(hex); } }Output48656C6C6F20686F772061726520796F7520686F7720646F20796F7520646F
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
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