Added Calculator

Created Calculator command line application using java's oops concepts

Author: Nokia-A6

Calculator-OOPS/Add.java

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+public class Add implements Operate{
+    @Override
+    public Double getResult(Double... numbers){
+        Double sum = 0.0;
+
+        for(Double num: numbers){
+            sum += num;
+        }
+        return sum;
+    }
+}

Calculator-OOPS/Calculator.java

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+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.Objects;
+import java.util.Queue;
+
+public class Calculator {
+    public static void main(String[] args){
+        final String inputExp = ReadInput.read();
+
+        Queue<String> operations;
+        Queue<String> numbers;
+
+        String[] numbersArr = inputExp.split("[-+*/%]");
+//        String[] operArr = inputExp.split("[0-9]+");
+        String[] operArr = inputExp.split("\\d+");
+        numbers = new LinkedList<>(Arrays.asList(numbersArr));
+        operations = new LinkedList<>(Arrays.asList(operArr));
+
+        Double res = Double.parseDouble(Objects.requireNonNull(numbers.poll()));
+
+        while(!numbers.isEmpty()){
+            String opr = operations.poll();
+
+            Operate operate;
+            switch(Objects.requireNonNull(opr)){
+                case "+":
+                    operate = new Add();
+                    break;
+                case "-":
+                    operate = new Sub();
+                    break;
+                case "*":
+                    operate = new Multiply();
+                    break;
+                case "/":
+                    operate = new Divide();
+                    break;
+                case "%":
+                    operate = new Modulus();
+                    break;
+                default:
+                    continue;
+            }
+            Double num = Double.parseDouble(Objects.requireNonNull(numbers.poll()));
+            res = operate.getResult(res, num);
+        }
+
+        System.out.println(res);
+    }
+}

Calculator-OOPS/Divide.java

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+public class Divide implements Operate {
+    @Override
+    public Double getResult(Double... numbers){
+        Double div = numbers[0];
+
+        for(int i=1;i< numbers.length;i++){
+            div /= numbers[i];
+        }
+        return div;
+    }
+}

Calculator-OOPS/Modulus.java

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+public class Modulus implements Operate{
+    @Override
+    public Double getResult(Double... numbers){
+        Double mod = numbers[0];
+
+        for (int i = 1; i < numbers.length; i++) {
+            mod %= numbers[i];
+        }
+        return mod;
+    }
+}

Calculator-OOPS/Multiply.java

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+public class Multiply implements Operate {
+    @Override
+    public Double getResult(Double... numbers){
+        Double mul = 1.0;
+
+        for(Double num: numbers){
+            mul *= num;
+        }
+        return mul;
+    }
+
+}

Calculator-OOPS/Operate.java

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+public interface Operate {
+    Double getResult(Double... numbers);
+}

Calculator-OOPS/ReadInput.java

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+import java.util.Scanner;
+
+public class ReadInput {
+    public static String read(){
+        Scanner scanner = new Scanner(System.in);
+        
+        System.out.println("Input Expression Example: 4*3/2");
+        String inputLine = scanner.nextLine();
+        
+        scanner.close();
+        return inputLine;
+    }
+}

Calculator-OOPS/Sub.java

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+public class Sub implements Operate{
+    @Override
+    public Double getResult(Double... numbers){
+        Double sub = numbers[0];
+
+        for(int i=1;i< numbers.length;i++){
+            sub -= numbers[i];
+        }
+        return sub;
+    }
+}