Add JavaDoc to Income and Expense classes

src/main/java/no/ntnu/idatt1002/demo/data/Expense.java

 package no.ntnu.idatt1002.demo.data;
 
 public class Expense extends Item{
-
     private ExpenseCategory category;
 
-
+    /**
+     * This constructor uses the super constructor to set the fields for 'amount' and 'recurring' and then sets the
+     * category. A IllegalArgumentException from this constructor if the category is left blank. The description
+     * field is left to the default blank string.
+     *
+     * @param amount The amount of the current Expense object as a double.
+     * @param recurring True if the current Expense repeats at regular intervals.
+     * @param category The category to which the Expense belongs to, provided as a value of ExpenseCategory.
+     */
     public Expense(double amount, boolean recurring, ExpenseCategory category) {
         super(amount, recurring);
 
@@ -14,6 +21,14 @@ public class Expense extends Item{
         this.category = category;
     }
 
+    /**
+     * This constructor uses the super constructor to set the fields for 'amount', 'description' and 'recurring'
+     * and then sets the category. A IllegalArgumentException from this constructor if the category is left blank.
+     * @param description A description of the Expense as a String.
+     * @param amount The amount of the current Expense object as a double.
+     * @param recurring True if the current income repeats at regular intervals.
+     * @param category The category to which the Expense belongs to, provided as a value of ExpenseCategory
+     */
     public Expense(String description, double amount, boolean recurring, ExpenseCategory category) {
         super(description, amount, recurring);
         if(category == null) {
@@ -24,20 +39,20 @@ public class Expense extends Item{
     }
 
     /**
-     * The method returns the category to which the Item belongs as a value of the Category enum class.
-     * @return The category the Item belongs to as a value of the Category enum class.
+     * The method returns the category to which the Expense belongs as a value of the ExpenseCategory enum class.
+     * @return The category the Expense belongs to as a value of the ExpenseCategory enum class.
      */
     public ExpenseCategory getCategory() {
         return category;
     }
 
     /**
-     * The method sets the category of an item to a value of the Category enum class.
-     * @param expenseCategory The category to which the Item should belong.
+     * The method sets the category of an expense to a value of the ExpenseCategory enum class.
+     * @param expenseCategory The category to which the expense belongs as a value of the ExpenseCategory enum.
      */
     public void setCategory(ExpenseCategory expenseCategory) {
         if(expenseCategory == null) {
-            throw new IllegalArgumentException("The category must be valid.");
+            throw new IllegalArgumentException("The income must belong to a category.");
         }
         this.category = expenseCategory;
     }

src/main/java/no/ntnu/idatt1002/demo/data/ExpenseCategory.java

@@ -4,6 +4,7 @@ public enum ExpenseCategory {
 
     FOOD,
     CLOTHES,
+    BOOKS,
     OTHER,
 
 }

src/main/java/no/ntnu/idatt1002/demo/data/Income.java

 package no.ntnu.idatt1002.demo.data;
 
+/**
+ * The Income class inherits from the Item class. The Item class additionally has a private field for an
+ * enum value of IncomeCategory.
+ *
+ * @author Hanne-Sofie
+ */
 public class Income extends Item{
 
     private IncomeCategory category;
 
+    /**
+     * This constructor uses the super constructor to set the fields for 'amount' and 'recurring' and then sets the
+     * category. A IllegalArgumentException from this constructor if the category is left blank. The description
+     * field is left to the default blank string.
+     *
+     * @param amount The amount of the current income object as a double.
+     * @param recurring True if the current income repeats at regular intervals.
+     * @param category The category to which the Income belongs to, provided as a value of IncomeCategory.
+     */
     public Income(double amount, boolean recurring, IncomeCategory category) {
         super(amount, recurring);
 
@@ -13,6 +28,14 @@ public class Income extends Item{
         this.category = category;
     }
 
+    /**
+     * This constructor uses the super constructor to set the fields for 'amount', 'description' and 'recurring'
+     * and then sets the category. A IllegalArgumentException from this constructor if the category is left blank.
+     * @param description A description of the income as a String.
+     * @param amount The amount of the current income object as a double.
+     * @param recurring True if the current income repeats at regular intervals.
+     * @param category The category to which the income belongs to, provided as a value of IncomeCategory
+     */
     public Income(String description, double amount, boolean recurring, IncomeCategory category) {
         super(description, amount, recurring);
         if(category == null) {
@@ -23,8 +46,8 @@ public class Income extends Item{
     }
 
     /**
-     * The method returns the category to which the Item belongs as a value of the Category enum class.
-     * @return The category the Item belongs to as a value of the Category enum class.
+     * The method returns the category to which the Income belongs as a value of the IncomeCategory enum.
+     * @return The category to which the Income belongs to as a value of the IncomeCategory enum.
      */
     public IncomeCategory getCategory() {
         return category;
@@ -32,7 +55,7 @@ public class Income extends Item{
 
     /**
      * The method sets the category of an item to a value of the Category enum class.
-     * @param category The category to which the Item should belong.
+     * @param category The category to which the Income belongs to as a value of the IncomeCategory enum.
      */
     public void setCategory(IncomeCategory category) {
         if(category == null) {