Removed Operator interface and classes dependence. Operators are hardcoded

src/main/java/no/uib/inf101/calculator/Calculator.java

 package no.uib.inf101.calculator;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -17,41 +18,8 @@ import no.uib.inf101.calculator.operations.Subtraction;
  */
 public class Calculator {
 
-    /**
-     * A map of operator symbols to their corresponding Operator implementations
-     */
-    private Map<String, Operator> operators;
 
     public Calculator() {
-        this.operators = new HashMap<>();
-        addOperators();
-    }
-
-    /**
-     * Adds the default operators such as Addition, Subtraction, Multiplication to the calculator.
-     */
-    private void addOperators() {
-        addOperator(new Addition());
-        addOperator(new Subtraction());
-        addOperator(new Multiplication());
-    }
-
-    /**
-     * Adds a single operator to the calculator.
-     * @param operator an implementation of the `Operator` interface
-     */
-    private void addOperator(Operator operator) {
-        operators.put(operator.getSymbol(), operator);
-    }
-
-    /**
-     * Retrieves an operator by its symbol.
-     *
-     * @param symbol the symbol of the operator (e.g., "+", "-", "*")
-     * @return the `Operator` object corresponding to the symbol, or null if not found
-     */
-    public Operator getOperator(String symbol) {
-        return operators.get(symbol);
     }
 
     /**
@@ -60,7 +28,8 @@ public class Calculator {
      * @return a list of operator symbols
      */
     public List<String> getOperatorSymbols() {
-        return new ArrayList<String>(operators.keySet());
+        String[] operators = new String[]{"+", "-", "*"};
+        return new ArrayList<String>(Arrays.asList(operators));
     }
 
     /**
@@ -77,8 +46,6 @@ public class Calculator {
         Expression operand1 = expression.getOperand1();
         Expression operand2 = expression.getOperand2();
         String operatorSymbol = expression.getOperator();
-        if (!operators.containsKey(operatorSymbol))
-            throw new IllegalArgumentException("The operator is not supported by the caluclator: " + operatorSymbol);
 
         return evaluate(evaluate(operand1), evaluate(operand2), operatorSymbol);
     }
@@ -93,7 +60,16 @@ public class Calculator {
      * @throws NullPointerException if the operator is not found in the calculator
      */
     private double evaluate(double num1, double num2, String operatorSymbol) {
-        return operators.get(operatorSymbol).calculate(num1, num2);
+        if (operatorSymbol.equals("+")) {
+            return num1 + num2;
+        }
+        if (operatorSymbol.equals("-")) {
+            return num1 - num2;
+        }
+        if (operatorSymbol.equals("*")) {
+            return num1 * num2;
+        }
+        throw new IllegalArgumentException("The operator is not supported by the calculator: " + operatorSymbol);
     }
     
 }

src/main/java/no/uib/inf101/calculator/gui/CalculatorGUI.java

@@ -9,7 +9,6 @@ import java.awt.GridLayout;
 import java.awt.Toolkit;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
-import java.io.FileNotFoundException;
 import java.net.URI;
 import java.util.List;