Move age calculation to DateTimeHelpers

Also add unit test and make sure that leap years are handled correctly.

android_app/app/src/main/java/com/health/openscale/core/datatypes/ScaleUser.java

@@ -20,6 +20,8 @@ import android.arch.persistence.room.ColumnInfo;
 import android.arch.persistence.room.Entity;
 import android.arch.persistence.room.PrimaryKey;
 
+import com.health.openscale.core.utils.DateTimeHelpers;
+
 import java.util.Calendar;
 import java.util.Date;
 
@@ -124,8 +126,7 @@ public class ScaleUser {
         this.goalDate = goalDate;
     }
 
-    public boolean isMale()
+    public boolean isMale() {
-    {
         if (gender == 0)
             return true;
 
@@ -133,19 +134,17 @@ public class ScaleUser {
     }
 
     public int getAge(Date todayDate) {
-        Calendar cal_today = Calendar.getInstance();
+        Calendar calToday = Calendar.getInstance();
-        cal_today.setTime(todayDate);
+        calToday.setTime(todayDate);
-        Calendar cal_birthday = Calendar.getInstance();
-        cal_birthday.setTime(birthday);
-        int userAge = cal_today.get(Calendar.YEAR) - cal_birthday.get(Calendar.YEAR);
-        if (cal_today.get(Calendar.DAY_OF_YEAR) < cal_birthday.get(Calendar.DAY_OF_YEAR)) userAge--;
 
-        return userAge;
+        Calendar calBirthday = Calendar.getInstance();
+        calBirthday.setTime(birthday);
+
+        return DateTimeHelpers.yearsBetween(calBirthday, calToday);
     }
 
     public void setInitialWeight(float weight) {
         this.initialWeight = weight;
-
     }
 
     public void setConvertedInitialWeight(float weight) {

android_app/app/src/main/java/com/health/openscale/core/utils/DateTimeHelpers.java

@@ -1,4 +1,4 @@
-/* Copyright (C) 2017 Erik Johansson <erik@ejohansson.se>
+/* Copyright (C) 2017-2018 Erik Johansson <erik@ejohansson.se>
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
@@ -39,4 +39,17 @@ public final class DateTimeHelpers {
 
         return days;
     }
+
+    static public int yearsBetween(Calendar start, Calendar end) {
+        int years = end.get(Calendar.YEAR) - start.get(Calendar.YEAR);
+
+        final int startMonth = start.get(Calendar.MONTH);
+        final int endMonth = end.get(Calendar.MONTH);
+        if (endMonth < startMonth
+            || (endMonth == startMonth
+                && end.get(Calendar.DAY_OF_MONTH) < start.get(Calendar.DAY_OF_MONTH))) {
+            years -= 1;
+        }
+        return years;
+    }
 }

android_app/app/src/test/java/com.health.openscale/DateTimeHelpersTest.java

@@ -1,4 +1,4 @@
-/* Copyright (C) 2017 Erik Johansson <erik@ejohansson.se>
+/* Copyright (C) 2017-2018 Erik Johansson <erik@ejohansson.se>
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
@@ -77,4 +77,33 @@ public class DateTimeHelpersTest {
                 getDate(2014, 12, 31),
                 getDate(2017, 1, 1)));
     }
+
+    @Test
+    public void yearsBetween() throws Exception {
+        assertEquals(19,
+                DateTimeHelpers.yearsBetween(
+                        getDate(1980, 3, 26),
+                        getDate(2000, 3, 25)));
+        assertEquals(20,
+                DateTimeHelpers.yearsBetween(
+                        getDate(1980, 3, 26),
+                        getDate(2000, 3, 26)));
+        assertEquals(20,
+                DateTimeHelpers.yearsBetween(
+                        getDate(1980, 3, 26),
+                        getDate(2000, 3, 27)));
+
+        assertEquals(0,
+                DateTimeHelpers.yearsBetween(
+                        getDate(2000, 3, 1),
+                        getDate(2001, 2, 28)));
+        assertEquals(1,
+                DateTimeHelpers.yearsBetween(
+                        getDate(2000, 3, 1),
+                        getDate(2001, 3, 1)));
+        assertEquals(1,
+                DateTimeHelpers.yearsBetween(
+                        getDate(2000, 3, 1),
+                        getDate(2001, 3, 2)));
+    }
 }