Category: java Generics

Java Generics – Environment Setup ”; Previous Next Local Environment Setup JUnit is a framework for Java, so the very first requirement is to have JDK installed in your machine. System Requirement JDK 1.5 or above. Memory No minimum requirement. Disk Space No minimum requirement. Operating System No minimum requirement. Step 1: Verify Java Installation in Your Machine First of all, open the console and execute a java command based on the operating system you are working on. OS Task Command Windows Open Command Console c:> java -version Linux Open Command Terminal $ java -version Mac Open Terminal machine:< joseph$ java -version Let”s verify the output for all the operating systems − OS Output Windows java version “1.6.0_21” Java(TM) SE Runtime Environment (build 1.6.0_21-b07) Java HotSpot(TM) Client VM (build 17.0-b17, mixed mode, sharing) Linux java version “1.6.0_21” Java(TM) SE Runtime Environment (build 1.6.0_21-b07) Java HotSpot(TM) Client VM (build 17.0-b17, mixed mode, sharing) Mac java version “1.6.0_21” Java(TM) SE Runtime Environment (build 1.6.0_21-b07) Java HotSpot(TM)64-Bit Server VM (build 17.0-b17, mixed mode, sharing) If you do not have Java installed on your system, then download the Java Software Development Kit (SDK) from the following link https://www.oracle.com. We are assuming Java 1.6.0_21 as the installed version for this tutorial. Step 2: Set JAVA Environment Set the JAVA_HOME environment variable to point to the base directory location where Java is installed on your machine. For example. OS Output Windows Set the environment variable JAVA_HOME to C:Program FilesJavajdk1.6.0_21 Linux export JAVA_HOME = /usr/local/java-current Mac export JAVA_HOME = /Library/Java/Home Append Java compiler location to the System Path. OS Output Windows Append the string C:Program FilesJavajdk1.6.0_21bin at the end of the system variable, Path. Linux export PATH = $PATH:$JAVA_HOME/bin/ Mac not required Verify Java installation using the command java -version as explained above. Print Page Previous Next Advertisements ”;

Java Generics Tutorial Quick Guide Resources Job Search Discussion Java Generic methods and generic classes enable programmers to specify, with a single method declaration, a set of related methods, or with a single class declaration, a set of related types, respectively. Generics also provide compile-time type safety that allows programmers to catch invalid types at compile time. This reference will take you through simple and practical methods using Java Generics. Audience This reference has been prepared for the beginners to help them understand the basic functionality related to functionality available in Java Generics. Prerequisites Before you start doing practice with various types of examples given in this reference, I”m making an assumption that you are already aware of basic Java Programming. Print Page Previous Next Advertisements ”;

Java Generics – Methods ”; Previous Next You can write a single generic method declaration that can be called with arguments of different types. Based on the types of the arguments passed to the generic method, the compiler handles each method call appropriately. Following are the rules to define Generic Methods − All generic method declarations have a type parameter section delimited by angle brackets (< and >) that precedes the method”s return type ( < E > in the next example). Each type parameter section contains one or more type parameters separated by commas. A type parameter, also known as a type variable, is an identifier that specifies a generic type name. The type parameters can be used to declare the return type and act as placeholders for the types of the arguments passed to the generic method, which are known as actual type arguments. A generic method”s body is declared like that of any other method. Note that type parameters can represent only reference types, not primitive types (like int, double and char). Example Following example illustrates how we can print an array of different type using a single Generic method − Live Demo public class GenericMethodTest { // generic method printArray public static < E > void printArray( E[] inputArray ) { // Display array elements for(E element : inputArray) { System.out.printf(“%s “, element); } System.out.println(); } public static void main(String args[]) { // Create arrays of Integer, Double and Character Integer[] intArray = { 1, 2, 3, 4, 5 }; Double[] doubleArray = { 1.1, 2.2, 3.3, 4.4 }; Character[] charArray = { ”H”, ”E”, ”L”, ”L”, ”O” }; System.out.println(“Array integerArray contains:”); printArray(intArray); // pass an Integer array System.out.println(“nArray doubleArray contains:”); printArray(doubleArray); // pass a Double array System.out.println(“nArray characterArray contains:”); printArray(charArray); // pass a Character array } } This will produce the following result − Output Array integerArray contains: 1 2 3 4 5 Array doubleArray contains: 1.1 2.2 3.3 4.4 Array characterArray contains: H E L L O Print Page Previous Next Advertisements ”;