Convert MidnightTimer to Kotlin

Part of the conversion to Kotlin of the whole
org.jsoron.uhabits.core.utils package.

android/uhabits-core/src/main/java/org/isoron/uhabits/core/utils/MidnightTimer.java

@@ -1,77 +0,0 @@
-/*
- * Copyright (C) 2017 Álinson Santos Xavier <isoron@gmail.com>
- *
- * This file is part of Loop Habit Tracker.
- *
- * Loop Habit Tracker is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by the
- * Free Software Foundation, either version 3 of the License, or (at your
- * option) any later version.
- *
- * Loop Habit Tracker is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
- * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package org.isoron.uhabits.core.utils;
-
-import org.isoron.uhabits.core.*;
-
-import java.util.*;
-import java.util.concurrent.*;
-
-import javax.inject.*;
-
-/**
- * A class that emits events when a new day starts.
- */
-@AppScope
-public class MidnightTimer
-{
-    private final List<MidnightListener> listeners;
-
-    private ScheduledExecutorService executor;
-
-    @Inject
-    public MidnightTimer()
-    {
-        this.listeners = new LinkedList<>();
-    }
-
-    public synchronized void addListener(MidnightListener listener)
-    {
-        this.listeners.add(listener);
-    }
-
-    public synchronized void onPause()
-    {
-        executor.shutdownNow();
-    }
-
-    public synchronized void onResume()
-    {
-        executor = Executors.newSingleThreadScheduledExecutor();
-        executor.scheduleAtFixedRate(() -> notifyListeners(),
-            DateUtils.millisecondsUntilTomorrowWithOffset() + 1000,
-            DateUtils.DAY_LENGTH, TimeUnit.MILLISECONDS);
-    }
-
-    public synchronized void removeListener(MidnightListener listener)
-    {
-        this.listeners.remove(listener);
-    }
-
-    private synchronized void notifyListeners()
-    {
-        for (MidnightListener l : listeners) l.atMidnight();
-    }
-
-    public interface MidnightListener
-    {
-        void atMidnight();
-    }
-}

android/uhabits-core/src/main/java/org/isoron/uhabits/core/utils/MidnightTimer.kt

@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2017 Álinson Santos Xavier <isoron@gmail.com>
+ *
+ * This file is part of Loop Habit Tracker.
+ *
+ * Loop Habit Tracker is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * Loop Habit Tracker is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.isoron.uhabits.core.utils
+
+import org.isoron.uhabits.core.AppScope
+import java.util.LinkedList
+import java.util.concurrent.Executors
+import java.util.concurrent.ScheduledExecutorService
+import java.util.concurrent.TimeUnit
+import javax.inject.Inject
+
+/**
+ * A class that emits events when a new day starts.
+ */
+@AppScope
+class MidnightTimer @Inject constructor() {
+    private val listeners: MutableList<MidnightListener> = LinkedList()
+    private lateinit var executor: ScheduledExecutorService
+
+    @Synchronized fun addListener(listener: MidnightListener) {
+        this.listeners.add(listener)
+    }
+
+    @Synchronized fun onPause() = executor.shutdownNow()
+
+    @Synchronized fun onResume() {
+        executor = Executors.newSingleThreadScheduledExecutor()
+        executor.scheduleAtFixedRate(
+            { notifyListeners() },
+            DateUtils.millisecondsUntilTomorrowWithOffset() + 1000,
+            DateUtils.DAY_LENGTH,
+            TimeUnit.MILLISECONDS
+        )
+    }
+
+    @Synchronized fun removeListener(listener: MidnightListener) = this.listeners.remove(listener)
+
+    @Synchronized private fun notifyListeners() {
+        for (l in listeners) {
+            l.atMidnight()
+        }
+    }
+
+    interface MidnightListener {
+        fun atMidnight()
+    }
+}