src/Kotlin/Libs/objectbox.md

+*Entity-Definition*
+```kotlin
+@Entity
+data class Message(
+    @Id var id: Long = 0L,
+    val title: String,
+    val text: String
+)
+```
+
+*Speicher*
+
+```kotlin
+val store = MyObjectBox.builder()
+    .name("objectbox-messages-db")
+    .build()
+val messages = store.boxFor<Message>()
+```
+
+*Create*
+
+```kotlin
+fun newMessage(messages: Box<Message>) {
+    print("Title: ")
+    val title = readLine()
+    println("Text: ")
+    val text = readLine()
+
+    if (!title.isNullOrEmpty() && !text.isNullOrEmpty()) {
+        messages.put(Message(title = title, text = text))
+    }
+}
+```
+
+*Delete*
+
+```kotlin
+fun deleteMessage(messages: Box<Message>) {
+    displayMessages(messages)
+
+    println(print("Id to delete: "))
+    val id = readLine()?.toLongOrNull()
+    if (id != null && messages.get(id) != null) {
+        messages.remove(id)
+    }
+}
+```
+
+*List*
+
+```kotlin
+fun displayMessages(messages: Box<Message>) {
+    messages.all.forEach {
+        println(it)
+    }
+}
+```
+
+*Search*
+
+```kotlin
+fun searchMessages(messages: Box<Message>) {
+    print("Suche eingeben: ")
+    val search = readLine()
+
+    if (!search.isNullOrEmpty())
+        messages.query()
+            .contains(Message_.title, search).or().contains(Message_.text, search)
+            .build().find().forEach { msg ->
+                println(msg)
+            }
+}
+```
+
+*Beispiel-Nutzung*
+
+```kotlin
+fun main() {
+    while (true) {
+        println("Menü:")
+        println("(n)eue Nachricht")
+        println("Nachricht (l)öschen")
+        println("Nachrichten (a)nzeigen")
+        println("Nachrichten (s)uchen")
+        println("(b)eenden")
+        val menuSelection = readLine()
+
+        when (menuSelection) {
+            "n" -> newMessage(messages)
+            "l" -> deleteMessage(messages)
+            "a" -> displayMessages(messages)
+            "s" -> searchMessages(messages)
+            "b" -> break
+        }
+    }
+}
+```
+
+Aufgabe
+-------
+
+Speichere die Historie in einer objectbox