Chain of Responsibility design pattern - BONUS EXAMPLE - Number ident…

…ifier program

patternBonus/src/com/premaseem/chainOfResponsibility/numberHandler/Client.java

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+package com.premaseem.chainOfResponsibility.numberHandler;
+
+/*
+@author: Aseem Jain
+@title: Design Patterns with Java 9
+@link: https://premaseem.wordpress.com/category/computers/design-patterns/
+*/
+
+import java.util.Scanner;
+
+public class Client {
+
+public static void main(String[] args) {
+
+System.out.println("Welcome to Number identifier program designed using Chain of Responsibility ");
+Scanner scan = new Scanner(System.in);
+
+NumberChain positiveNumberHandler = new PositiveNumberHandler();
+NumberChain negativeNumberHandler = new NegativeNumberHandler();
+NumberChain neutralNumberHandler = new ZeroNumberHandler();
+
+// Setting up the chain
+positiveNumberHandler.setNextHandler(negativeNumberHandler);
+negativeNumberHandler.setNextHandler(neutralNumberHandler);
+
+String repeatRunFlag = "y";
+while (!repeatRunFlag.equalsIgnoreCase("no")) {
+System.out.println("Please enter any number 0, less then or greater then zero eg. -22 or 89 ? ");
+int choice = scan.nextInt();
+positiveNumberHandler.handler(choice);
+
+System.out.println("=============================");
+
+System.out.println("Press No to Exit and any other character to repeat .... ");
+try {
+repeatRunFlag = scan.next();
+} catch (Exception e) {
+repeatRunFlag = "n";
+}
+}
+
+System.out.println("\n $$$$$$$$$$$$$$$$$$$$ Thanks by Prem Aseem $$$$$$$$$$$$$$$$$$$$$$ \n ");
+System.out.println("\n $$$$$$$$$$$$$$$$$$$$$ www.premaseem.me $$$$$$$$$$$$$$$$$$$$$$ \n ");
+
+}
+}

patternBonus/src/com/premaseem/chainOfResponsibility/numberHandler/NumberChain.java

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+package com.premaseem.chainOfResponsibility.numberHandler;
+
+public abstract class NumberChain {
+
+NumberChain nextHandler = null;
+
+public NumberChain setNextHandler(NumberChain nextHandler) {
+this.nextHandler = nextHandler;
+return this.nextHandler;
+}
+
+public abstract void handler(int requestNumber);
+
+}
+
+class PositiveNumberHandler extends NumberChain {
+
+@Override
+public void handler(int requestNumber) {
+if (requestNumber > 0) {
+System.out.println(this.getClass().getSimpleName() +" handled number " + requestNumber);
+}else{
+if(nextHandler!=null)
+nextHandler.handler(requestNumber);
+}
+}
+}
+
+class NegativeNumberHandler extends NumberChain {
+
+@Override
+public void handler(int requestNumber) {
+if (requestNumber < 0) {
+System.out.println(this.getClass().getSimpleName() +" handled number " + requestNumber);
+}else{
+if(nextHandler!=null)
+nextHandler.handler(requestNumber);
+}
+}
+}
+
+class ZeroNumberHandler extends NumberChain {
+
+@Override
+public void handler(int requestNumber) {
+if (requestNumber == 0) {
+System.out.println(this.getClass().getSimpleName() +" handled number " + requestNumber);
+}else{
+if(nextHandler!=null)
+nextHandler.handler(requestNumber);
+}
+}
+}