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Completed string calculator, added a case for division. #4

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Completed string calculator, added a case for division. #4

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37 changes: 35 additions & 2 deletions src/main/java/com/serenitydojo/calculator/Calculator.java
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Original file line number Diff line number Diff line change
@@ -1,7 +1,40 @@
package com.serenitydojo.calculator;

import org.apache.commons.lang3.StringUtils;

public class Calculator {
public int evaluate(String expression) {
return 0;
if(expression.isEmpty()) {
return 0;
}

int calculationResult = 0;
String currentOperator = "+";

String[] characters = expression.split("\\s");

for(String character : characters) {
if (!StringUtils.isNumeric(character)) {
currentOperator = character;
} else {
calculationResult = calculation(calculationResult, currentOperator, character);
}
}
return calculationResult;
}

private int calculation(int calculationResult, String currentOperator, String character) throws IllegalMathsOperatorException {
switch(currentOperator) {
case "+":
return calculationResult + Integer.parseInt(character);
case "-":
return calculationResult - Integer.parseInt(character);
case "*":
return calculationResult * Integer.parseInt(character);
case "/":
return calculationResult / Integer.parseInt(character);
default:
throw new IllegalMathsOperatorException(currentOperator + " operator is not supported!");
}
}
}
}
7 changes: 7 additions & 0 deletions src/main/java/com/serenitydojo/calculator/IllegalMathsOperatorException.java
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@@ -0,0 +1,7 @@
package com.serenitydojo.calculator;

public class IllegalMathsOperatorException extends RuntimeException {
public IllegalMathsOperatorException(String message) {
super(message);
}
}
75 changes: 40 additions & 35 deletions src/test/java/com/serenitydojo/calculator/WhenDoingMaths.java
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Original file line number Diff line number Diff line change
Expand Up @@ -13,38 +13,43 @@ public void shouldReturnZeroForAnEmptyString() {
assertThat(calculator.evaluate("")).isEqualTo(0);
}

// @Test(expected = IllegalMathsOperatorException.class)
// public void shouldReportNonSupportedOperations() {
// calculator.evaluate("1 ^ 2");
// }
//
// @Test
// public void shouldReturnTheValueOfASingleNumber() {
// assertThat(calculator.evaluate("1")).isEqualTo(1);
// }
//
// @Test
// public void shouldAddTwoNumbers() {
// assertThat(calculator.evaluate("1 + 1")).isEqualTo(2);
// }
//
// @Test
// public void shouldAddThreeNumbers() {
// assertThat(calculator.evaluate("1 + 2 + 3")).isEqualTo(6);
// }
//
// @Test
// public void shouldAlsoSubtract() {
// assertThat(calculator.evaluate("10 - 6")).isEqualTo(4);
// }
//
// @Test
// public void shouldAddAndSubtract() {
// assertThat(calculator.evaluate("10 + 5 - 6")).isEqualTo(9);
// }
//
// @Test
// public void shouldMultiplyNumbers() {
// assertThat(calculator.evaluate("10 * 5")).isEqualTo(50);
// }
}
@Test(expected = IllegalMathsOperatorException.class)
public void shouldReportNonSupportedOperations() {
calculator.evaluate("1 ^ 2");
}

@Test
public void shouldReturnTheValueOfASingleNumber() {
assertThat(calculator.evaluate("1")).isEqualTo(1);
}

@Test
public void shouldAddTwoNumbers() {
assertThat(calculator.evaluate("1 + 1")).isEqualTo(2);
}

@Test
public void shouldAddThreeNumbers() {
assertThat(calculator.evaluate("1 + 2 + 3")).isEqualTo(6);
}

@Test
public void shouldAlsoSubtract() {
assertThat(calculator.evaluate("10 - 6")).isEqualTo(4);
}

@Test
public void shouldAddAndSubtract() {
assertThat(calculator.evaluate("10 + 5 - 6")).isEqualTo(9);
}

@Test
public void shouldMultiplyNumbers() {
assertThat(calculator.evaluate("10 * 5")).isEqualTo(50);
}

@Test
public void shouldDivideNumbers() {
assertThat(calculator.evaluate("25 / 5")).isEqualTo(5);
}
}