[java] [student_grades] Replace Error Code with Exception

Author: JavierCane

examples/java/java-student_grades-03_if_guard_clause/src/main/java/tv/codely/student_grades/GradesWeightBelowMinException.java

@@ -0,0 +1,4 @@
+package tv.codely.student_grades;
+
+public final class GradesWeightBelowMinException extends IllegalArgumentException{
+}

examples/java/java-student_grades-03_if_guard_clause/src/main/java/tv/codely/student_grades/GradesWeightOverMaxException.java

@@ -0,0 +1,4 @@
+package tv.codely.student_grades;
+
+public final class GradesWeightOverMaxException extends IllegalArgumentException{
+}

examples/java/java-student_grades-03_if_guard_clause/src/main/java/tv/codely/student_grades/StudentGradeCalculator.java

@@ -41,9 +41,9 @@ public float calculateGrades(final List<Pair<Integer, Float>> examsGrades, final
         int gradesWeightSum = gradesWeightSum(examsGrades);
 
         if (gradesWeightSum > 100) {
-            return -1f;
+            throw new GradesWeightOverMaxException();
         } else if (gradesWeightSum < 100) {
-            return -2f;
+            throw new GradesWeightBelowMinException();
         }
 
         float gradesSum = gradesSum(examsGrades);

examples/java/java-student_grades-03_if_guard_clause/src/test/java/tv/codely/student_grades/StudentGradeCalculatorShould.java

@@ -6,6 +6,7 @@
 import java.util.List;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 public class StudentGradeCalculatorShould {
     @Test
@@ -127,7 +128,10 @@ void validate_all_exam_grades_weight_below_100() {
         );
         final boolean hasReachedMinimumClasses = true;
 
-        assertEquals(-2, studentGradeCalculator.calculateGrades(examsGrades, hasReachedMinimumClasses));
+        assertThrows(
+            GradesWeightBelowMinException.class,
+            () -> studentGradeCalculator.calculateGrades(examsGrades, hasReachedMinimumClasses)
+        );
     }
 
     @Test
@@ -140,7 +144,10 @@ void validate_all_exam_grades_weight_over_100() {
         );
         final boolean hasReachedMinimumClasses = true;
 
-        assertEquals(-1, studentGradeCalculator.calculateGrades(examsGrades, hasReachedMinimumClasses));
+        assertThrows(
+            GradesWeightOverMaxException.class,
+            () -> studentGradeCalculator.calculateGrades(examsGrades, hasReachedMinimumClasses)
+        );
     }
 
     // hasToRaiseOnePoint