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Author: UnknownJoe796

src/main/java/com/lightningkite/kotlin/collection/List.ext.kt

@@ -10,7 +10,6 @@ import java.util.*
 inline fun <E> List<E>.random(): E {
     return this[Math.random().times(size).toInt()]
 }
-
 fun <E> SetupList(setup: (E) -> Unit): MutableList<E> {
     return object : ArrayList<E>() {
         override fun addAll(index: Int, elements: Collection<E>): Boolean {

src/main/java/com/lightningkite/kotlin/collection/ObserveEmptyArrayList.kt

@@ -0,0 +1,62 @@
+package com.lightningkite.kotlin.collection
+
+import java.util.*
+
+/**
+ * Created by joseph on 12/2/16.
+ */
+abstract class ObserveEmptyArrayList<E>() : ArrayList<E>() {
+
+    abstract fun onNotEmpty(): Unit
+    abstract fun onEmpty(): Unit
+
+    var active = false
+    private fun checkUp() {
+        if (!super.isEmpty() && !active) {
+            active = true
+            onNotEmpty()
+        }
+    }
+
+    private fun checkDown() {
+        if (super.isEmpty() && active) {
+            active = false
+            onEmpty()
+        }
+    }
+
+    override fun add(element: E): Boolean {
+        val result = super.add(element)
+        checkUp()
+        return result
+    }
+
+    override fun addAll(elements: Collection<E>): Boolean {
+        val result = super.addAll(elements)
+        checkUp()
+        return result
+    }
+
+    override fun clear() {
+        super.clear()
+        checkDown()
+    }
+
+    override fun remove(element: E): Boolean {
+        val result = super.remove(element)
+        checkDown()
+        return result
+    }
+
+    override fun removeAll(elements: Collection<E>): Boolean {
+        val result = super.removeAll(elements)
+        checkDown()
+        return result
+    }
+
+    override fun retainAll(elements: Collection<E>): Boolean {
+        val result = super.retainAll(elements)
+        checkDown()
+        return result
+    }
+}