Improved binary operator and equals button

app/src/main/java/htw/berlin/prog2/ha1/Calculator.java

@@ -14,6 +14,9 @@ public class Calculator {
 
     private String latestOperation = "";
 
+    // Add a Logger instance
+    private Logger logger = new Logger();
+
     /**
      * @return den aktuellen Bildschirminhalt als String
      */
@@ -34,6 +37,14 @@ public void pressDigitKey(int digit) {
         if(screen.equals("0") || latestValue == Double.parseDouble(screen)) screen = "";
 
         screen = screen + digit;
+
+        logger.logButtonClick(String.valueOf(digit));
+        if (!latestOperation.isEmpty()){
+            logger.logCurrentEquation(String.valueOf(latestValue)+latestOperation+screen);
+        }else{
+            logger.logCurrentEquation(String.valueOf(screen));
+        }
+
     }
 
     /**
@@ -48,6 +59,9 @@ public void pressClearKey() {
         screen = "0";
         latestOperation = "";
         latestValue = 0.0;
+
+        logger.logButtonClick("C");
+        logger.logCurrentEquation(String.valueOf(latestValue)+latestOperation+screen);
     }
 
     /**
@@ -60,8 +74,27 @@ public void pressClearKey() {
      * @param operation "+" für Addition, "-" für Substraktion, "x" für Multiplikation, "/" für Division
      */
     public void pressBinaryOperationKey(String operation)  {
+        // TODO: Error, falls nach Division Null eingegeben wird
+        // TODO: Wenn es nicht der erste Operand ist, dann zeige Zwischenergebnis auf Bildschirm an
+        if(operation.matches("[x/]") && latestOperation.matches("[+-]") ){
+
+        } else if (!latestOperation.isEmpty()){
+            // printe zwischenergebnis auf screen
+            var result = switch(latestOperation) {
+                case "+" -> latestValue + Double.parseDouble(screen);
+                case "-" -> latestValue - Double.parseDouble(screen);
+                case "x" -> latestValue * Double.parseDouble(screen);
+                case "/" -> latestValue / Double.parseDouble(screen);
+                default -> throw new IllegalArgumentException();
+            };
+            screen = Double.toString(result);
+        }
+
         latestValue = Double.parseDouble(screen);
         latestOperation = operation;
+
+        logger.logButtonClick(operation);
+        logger.logCurrentEquation(screen+latestOperation);
     }
 
     /**
@@ -84,6 +117,8 @@ public void pressUnaryOperationKey(String operation) {
         if(screen.equals("NaN")) screen = "Error";
         if(screen.contains(".") && screen.length() > 11) screen = screen.substring(0, 10);
 
+        logger.logButtonClick(operation);
+        logger.logCurrentEquation(screen);
     }
 
     /**
@@ -95,6 +130,9 @@ public void pressUnaryOperationKey(String operation) {
      */
     public void pressDotKey() {
         if(!screen.contains(".")) screen = screen + ".";
+
+        logger.logButtonClick(".");
+        logger.logCurrentEquation(screen);
     }
 
     /**
@@ -106,6 +144,13 @@ public void pressDotKey() {
      */
     public void pressNegativeKey() {
         screen = screen.startsWith("-") ? screen.substring(1) : "-" + screen;
+
+        logger.logButtonClick("+/-");
+        if (!latestOperation.isEmpty()){
+            logger.logCurrentEquation(String.valueOf(latestValue)+latestOperation+screen);
+        }else {
+            logger.logCurrentEquation(screen);
+        }
     }
 
     /**
@@ -128,6 +173,10 @@ public void pressEqualsKey() {
         screen = Double.toString(result);
         if(screen.equals("Infinity")) screen = "Error";
         if(screen.endsWith(".0")) screen = screen.substring(0,screen.length()-2);
+        if(screen.endsWith(".")) screen = screen.substring(0,screen.length()-1);
         if(screen.contains(".") && screen.length() > 11) screen = screen.substring(0, 10);
+
+        logger.logButtonClick("=");
+        logger.logCurrentEquation(screen);
     }
 }

app/src/main/java/htw/berlin/prog2/ha1/Logger.java

@@ -0,0 +1,12 @@
+package htw.berlin.prog2.ha1;
+
+public class Logger {
+    public void logButtonClick(String button) {
+        System.out.println("Button clicked: " + button);
+    }
+
+    public void logCurrentEquation(String equation) {
+        System.out.println("Current equation: " + equation);
+    }
+}
+

app/src/test/java/htw/berlin/prog2/ha1/CalculatorTest.java

@@ -26,6 +26,56 @@ void testPositiveAddition() {
         assertEquals(expected, actual);
     }
 
+    @DisplayName("should display result after subtracting a number from another number")
+    void testSubtraction() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(2);
+        calc.pressDigitKey(0);
+        calc.pressBinaryOperationKey("-");
+        calc.pressDigitKey(1);
+        calc.pressDigitKey(5);
+        calc.pressEqualsKey();
+
+        String expected = "5";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+
+    @DisplayName("should display result after multiplying two numbers")
+    void testMultiplication() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(2);
+        calc.pressDigitKey(0);
+        calc.pressBinaryOperationKey("*");
+        calc.pressDigitKey(1);
+        calc.pressDigitKey(5);
+        calc.pressEqualsKey();
+
+        String expected = "300";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+
+    @DisplayName("should display result after dividing a number by another")
+    void testDivision() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(2);
+        calc.pressDigitKey(0);
+        calc.pressBinaryOperationKey("/");
+        calc.pressDigitKey(4);
+        calc.pressEqualsKey();
+
+        String expected = "5";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+
     @Test
     @DisplayName("should display result after getting the square root of two")
     void testSquareRoot() {
@@ -40,6 +90,33 @@ void testSquareRoot() {
         assertEquals(expected, actual);
     }
 
+    @Test
+    @DisplayName("should show intermediate result after multiple binary operands")
+    void  testScreenOutputAfterMultipleBinaryOperands(){
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(7);
+        calc.pressBinaryOperationKey("x");
+        calc.pressDigitKey(5);
+        calc.pressBinaryOperationKey("x");
+
+        String actual = calc.readScreen();
+        double expected = 35;
+
+        assertEquals(expected, Double.valueOf(actual));
+    }
+    @Test
+    @DisplayName("should remove point if it is at the end")
+    void testRemovePoint(){
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(5);
+        calc.pressDotKey();
+        calc.pressEqualsKey();
+
+        String actual = calc.readScreen();
+        String expected = "5";
+
+        assertEquals(expected, actual);
+    }
     @Test
     @DisplayName("should display error when dividing by zero")
     void testDivisionByZero() {