Finalize the Expense class and add an Enum for the rate.

app/src/main/java/com/hyperling/expensetracker/Expense.kt

@@ -1,23 +1,13 @@
 package com.hyperling.expensetracker
 
-/*class Expense {
-    var name: String = ""
-    var cost: Double = 0.0
-    var freq: Char = '*'
-    var note: String = ""
+import androidx.room.Entity
+import androidx.room.PrimaryKey
 
-    /*public Expense (val name: String, val cost: Double, val freq: Char, val note: String) {
-        this.name = name
-        this.name = name
-        this.name = name
-        this.name = name
-    }*/
-}*/
-
-class Expense (
-    var name: String = "",
-    var cost: Double = 0.0,
-    var freq: Char = '*',
-    var note: String = "",
-) {
-}
+@Entity
+data class Expense (
+    val name: String,
+    val cost: Double,
+    val rate: Enum<Rate>,
+    @PrimaryKey(autoGenerate = true)
+    val ID: Int = 0,
+)

app/src/main/java/com/hyperling/expensetracker/Rate.kt

@@ -0,0 +1,8 @@
+package com.hyperling.expensetracker
+
+enum class Rate {
+    DAILY,
+    WEEKLY,
+    MONTHLY,
+    YEARLY,
+}