ha1 - Abgabe

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

@@ -14,6 +14,8 @@ public class Calculator {
 
     private String latestOperation = "";
 
+    private boolean newNumber = true;
+
     /**
      * @return den aktuellen Bildschirminhalt als String
      */
@@ -31,7 +33,13 @@ public String readScreen() {
     public void pressDigitKey(int digit) {
         if(digit > 9 || digit < 0) throw new IllegalArgumentException();
 
-        if(screen.equals("0") || latestValue == Double.parseDouble(screen)) screen = "";
+        if(screen.equals("-0")) {
+            screen = "-" + digit;
+            newNumber = false;
+            return;
+        }
+
+        if(screen.equals("0") || latestValue == Double.parseDouble(screen)) screen = ""; newNumber = false;
 
         screen = screen + digit;
     }
@@ -60,8 +68,14 @@ public void pressClearKey() {
      * @param operation "+" für Addition, "-" für Substraktion, "x" für Multiplikation, "/" für Division
      */
     public void pressBinaryOperationKey(String operation)  {
+        if(!latestOperation.isEmpty()) {
+            pressEqualsKey();
+        }
         latestValue = Double.parseDouble(screen);
         latestOperation = operation;
+
+        //screen = "0"; // stört den Punkt mit dem Zwischenergebnis bei einer weiteren Eingabe!
+        newNumber = true;
     }
 
     /**
@@ -105,6 +119,11 @@ public void pressDotKey() {
      * entfernt und der Inhalt fortan als positiv interpretiert.
      */
     public void pressNegativeKey() {
+
+        if(newNumber == true) {
+            screen = "0";
+            newNumber= false;
+        }
         screen = screen.startsWith("-") ? screen.substring(1) : "-" + screen;
     }
 

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

@@ -90,5 +90,111 @@ void testMultipleDecimalDots() {
 
 
     //TODO hier weitere Tests erstellen
+
+    @Test
+    @DisplayName("should display result after adding 2 negative numbers")
+    void testNegativeAddition() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(3);
+        calc.pressNegativeKey();
+        calc.pressBinaryOperationKey("+");
+        calc.pressDigitKey(5);
+        calc.pressNegativeKey();
+        calc.pressEqualsKey();
+
+        String expected = "-8";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("should display result after subtract 2 negative numbers, when negative key is pressed before digit key")
+    void testNegativeSubtractionNegativeKeyBefore() {
+        Calculator calc = new Calculator();
+
+        calc.pressNegativeKey();
+        calc.pressDigitKey(6);
+        calc.pressBinaryOperationKey("-");
+        calc.pressNegativeKey();
+        calc.pressDigitKey(2);
+        calc.pressEqualsKey();
+
+        String expected = "-4";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+
+    }
+
+    @Test
+    @DisplayName("should display result after subtract 2 negative numbers, when negative key is pressed after digit key")
+    void testNegativeSubtractionNegativeKeyAfter() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(6);
+        calc.pressNegativeKey();
+        calc.pressBinaryOperationKey("-");
+        calc.pressDigitKey(2);
+        calc.pressNegativeKey();
+        calc.pressEqualsKey();
+
+        String expected = "-4";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+
+    }
+    @Test
+    @DisplayName("display negative number, when negative key is pressed before digit key")
+    void testDisplayNegativeNumber() {
+        Calculator calc = new Calculator();
+
+        calc.pressNegativeKey();
+        calc.pressDigitKey(6);
+
+        String expected = "-6";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+    @Test
+    @DisplayName("display result after adding 3 positive numbers")
+    void testDisplayAddition3PositiveNumbers() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(5);
+        calc.pressBinaryOperationKey("+");
+        calc.pressDigitKey(5);
+        calc.pressBinaryOperationKey("+");
+        calc.pressDigitKey(5);
+        calc.pressEqualsKey();
+
+        String expected = "15";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+    @Test
+    @DisplayName("display result after adding 4 positive numbers")
+    void testDisplayAddition4PositiveNumbers() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(8);
+        calc.pressBinaryOperationKey("+");
+        calc.pressDigitKey(2);
+        calc.pressBinaryOperationKey("+");
+        calc.pressDigitKey(5);
+        calc.pressBinaryOperationKey("+");
+        calc.pressDigitKey(1);
+        calc.pressEqualsKey();
+
+        String expected = "16";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+
 }