Java Starts from scratch 17 (simple factory)

implementation of a simple factory

Implement a calculator: Require 2 numbers, and operators, to get results

Operation class

 PackageCom.pb.demo1; Public classOperation {Private DoubleNUM1; Private Doublenum2;  Public DoubleGetResult (DoubleNUM1,Doublenum2) {        DoubleResult=0; returnresult; }     Public DoublegetNum1 () {returnNUM1; }     Public voidSETNUM1 (DoubleNUM1) {         This. NUM1 =NUM1; }     Public DoublegetNum2 () {returnnum2; }     Public voidSETNUM2 (Doublenum2) {         This. num2 =num2; }    }

add, subtract, behave, divide, take the mold

 package   Com.pb.demo1;  /*   * addition  */ public  class  Addoperation extends   operation {@Override public  double  num1,  num2) {return  (Num1+num2); }}

 package   Com.pb.demo1;  /*   * subtract  */ public  class  Substruction extends   operation {@Override public  double  num1,  num2) { Span style= "color: #0000ff;"    >return  (Num1-num2); }    }

 package   Com.pb.demo1;  /*   good method  */ public  class  Multiplication extends   operation {@Override public  double  num1,  num2) {return  (Num1*num2); }    }

 package   Com.pb.demo1;  /*   Division  */ public  class  Division extends   operation {@Override  public  double  GetResult (double  NUM1, double   num2) { return  (Num1/num2); }    }

 Package Com.pb.demo1; /*  */Publicclassextends  operation    {    @Override  publicDouble GetResult (doubledouble  num2) {                return (num1%num2);    }    }

Factory class:

 PackageCom.pb.demo1;/** Simple Factory class*/ Public classFactory {//return type is class object     PublicOperation GetResult (String op) {operation Operation=NULL; //declares an object according to an operator and returns        Switch(OP) { Case"+": Operation=Newaddoperation ();  Break;  Case"-": Operation=Newsubstruction ();  Break;  Case"*": Operation=Newmultiplication ();  Break;  Case"/": Operation=NewDivision ();  Break;  Case"%": Operation=Newmodeoperation ();  Break; default: System.err.println ("The input operator is incorrect!");  Break; }        //returns the generated object        returnoperation; }}

Test class:

 PackageCom.pb.demo1;Importjava.util.InputMismatchException;ImportJava.util.Scanner;/** Calculator*/ Public classDemo1 { Public Static voidMain (string[] args) {//declaring a scanner type variableScanner input =NewScanner (system.in); //declaring a factory objectFactory fac=NewFactory (); Try{System.out.println ("Please enter the first integer:"); Doublenum1=input.nextdouble (); System.out.println ("Please enter a second integer:"); DoubleNum2=input.nextdouble (); System.out.println ("Please lose operator: + 、-、 *,/,%"); String op=Input.next (); //The returned object factory of the receiving factory generates objects based on the operatorOperation Operation=Fac.getresult (OP); //Receive calculation results            Doubleresult=Operation.getresult (NUM1, num2); //Show Calculation ResultsSystem.out.println (num1+ "and" +num2+ "Running results:" +result); }Catch(inputmismatchexception e) {System.err.println ("The input type is incorrect!"); }Catch(Exception e) {e.printstacktrace (); }    }}

Java Starts from scratch 17 (simple factory)