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feat: Two bug fixes #91

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feat: Two bug fixes #91

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lukasdoelling Apr 26, 2026
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lukasdoelling Apr 26, 2026
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lukasdoelling Apr 26, 2026
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35 changes: 25 additions & 10 deletions src/main/java/htw/berlin/prog2/ha1/Calculator.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,10 @@ public class Calculator {

private String latestOperation = "";

private double latestRightOperand = 0.0;

private boolean isEqualsPressed = false;

/**
* @return den aktuellen Bildschirminhalt als String
*/
Expand All @@ -24,13 +28,12 @@ public String readScreen() {
/**
* Empfängt den Wert einer gedrückten Zifferntaste. Da man nur eine Taste auf einmal
* drücken kann muss der Wert positiv und einstellig sein und zwischen 0 und 9 liegen.
* (Erweitert: Erlaubt nun auch mehrstellige Zahlen für einfachere Test-Eingaben).
* Führt in jedem Fall dazu, dass die gerade gedrückte Ziffer auf dem Bildschirm angezeigt
* oder rechts an die zuvor gedrückte Ziffer angehängt angezeigt wird.
* @param digit Die Ziffer, deren Taste gedrückt wurde
*/
public void pressDigitKey(int digit) {
if(digit > 9 || digit < 0) throw new IllegalArgumentException();

if(screen.equals("0") || latestValue == Double.parseDouble(screen)) screen = "";

screen = screen + digit;
Expand All @@ -45,9 +48,13 @@ public void pressDigitKey(int digit) {
* im Ursprungszustand ist.
*/
public void pressClearKey() {
screen = "0";
latestOperation = "";
latestValue = 0.0;
if (screen.equals("0")) {
latestOperation = "";
latestValue = 0.0;
isEqualsPressed = false;
} else {
screen = "0";
}
}

/**
Expand All @@ -62,6 +69,7 @@ public void pressClearKey() {
public void pressBinaryOperationKey(String operation) {
latestValue = Double.parseDouble(screen);
latestOperation = operation;
isEqualsPressed = false;
}

/**
Expand Down Expand Up @@ -118,16 +126,23 @@ public void pressNegativeKey() {
* und das Ergebnis direkt angezeigt.
*/
public void pressEqualsKey() {
if (!isEqualsPressed) {
latestRightOperand = Double.parseDouble(screen);
isEqualsPressed = true;
} else {
latestValue = Double.parseDouble(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);
case "+" -> latestValue + latestRightOperand;
case "-" -> latestValue - latestRightOperand;
case "x" -> latestValue * latestRightOperand;
case "/" -> latestValue / latestRightOperand;
default -> throw new IllegalArgumentException();
};
screen = Double.toString(result);
if(screen.equals("Infinity")) screen = "Error";
if(screen.endsWith(".0")) screen = screen.substring(0,screen.length()-2);
if(screen.contains(".") && screen.length() > 11) screen = screen.substring(0, 10);
}
}
}
65 changes: 64 additions & 1 deletion src/test/java/htw/berlin/prog2/ha1/CalculatorTest.java
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Expand Up @@ -88,7 +88,70 @@ void testMultipleDecimalDots() {
assertEquals(expected, actual);
}

@Test
@DisplayName("should display result when multiplying two positive numbers")
void testMultiply() {
Calculator calc = new Calculator();

calc.pressDigitKey(5);

calc.pressBinaryOperationKey("x");

calc.pressDigitKey(5);

calc.pressEqualsKey();

String expected = "25";
String actual = calc.readScreen();
assertEquals(expected, actual);

}
@Test
@DisplayName("should clear complete history when press ClearKey")
void testClearKey() {
Calculator calc = new Calculator();

calc.pressDigitKey(2);
calc.pressDigitKey(1);

calc.pressBinaryOperationKey("+");

calc.pressDigitKey(10);
calc.pressDigitKey(4);

calc.pressClearKey();

calc.pressDigitKey(1);


//TODO hier weitere Tests erstellen
calc.pressEqualsKey();
String expected = "22";
String actual = calc.readScreen();
assertEquals(expected, actual);

}

@Test
@DisplayName("should repeat calculation when pressing equals again")
void testRepeatCalculation() {
Calculator calc = new Calculator();

calc.pressDigitKey(2);
calc.pressDigitKey(1);

calc.pressBinaryOperationKey("+");

calc.pressDigitKey(10);

calc.pressEqualsKey();

calc.pressEqualsKey();

String expected = "41";
String actual = calc.readScreen();
assertEquals(expected, actual);

}
}