wrote notification kotlin extensions

eco-api/src/main/java/com/willfp/eco/core/command/CommandBase.java

@@ -125,7 +125,6 @@ public interface CommandBase {
      * @param key       key of notification message in langYml
      * @param <T>       the generic type of object
      * @return Returns the object given or throws an exception
-     * @throws NotificationException
      */
     default @NotNull <T> T notifyFalse(@NotNull T obj,
                                        @NotNull Predicate<T> predicate, @NotNull String key)
@@ -135,6 +134,7 @@ public interface CommandBase {
     }
 
     /**
+     * Throws an exception if condition is false.
      * @param condition the condition, throws exception if false
      * @param key       value in the langYml
      * @return Returns the condition given or throws an exception

eco-api/src/main/kotlin/com/willfp/eco/core/commands/CommandHelpers.kt

@@ -4,9 +4,13 @@ package com.willfp.eco.core.commands
 
 import com.willfp.eco.core.EcoPlugin
 import com.willfp.eco.core.command.CommandBase
+import com.willfp.eco.core.command.NotificationException
 import com.willfp.eco.core.command.impl.PluginCommand
 import com.willfp.eco.core.command.impl.Subcommand
+import org.bukkit.Bukkit
 import org.bukkit.command.CommandSender
+import org.bukkit.entity.Player
+import java.util.function.Predicate
 
 /**
  * Helper class for creating commands with builders.
@@ -141,3 +145,52 @@ fun CommandBase.addSubcommand(
     return command
 }
 
+/**
+ * Notify the player if an object is null.
+ *
+ * @param key The key of the message to send to the player if obj is null
+ * @return The object provided originally, for more null behavior
+ * @throws NotificationException
+ */
+fun <T> T.notifyNull(key: String): T {
+    if(this == null) {
+        throw NotificationException(key)
+    }
+    return this
+}
+
+/**
+ * Throws an exception if predicate tests false.
+ *
+ * @param predicate predicate to test
+ * @param key       key of notification message in langYml
+ * @return Returns the object given or throws an exception
+ * @throws NotificationException
+ */
+fun <T> T.notifyFalse(predicate: Predicate<T>, key: String): T {
+    predicate.test(this).notifyFalse(key)
+    return this
+}
+
+/**
+ * Throws an exception if boolean is false.
+ * @param key       value in the langYml
+ * @return Returns the condition given or throws an exception
+ * @throws NotificationException exception thrown when false
+ */
+fun Boolean.notifyFalse(key: String): Boolean {
+    return if(this) true else throw NotificationException(key)
+}
+
+/**
+ * Throws an exception and sends a lang message if Bukkit.getPlayer(receiver) is null
+ *
+ * @param key    value in the langYml
+ * @return Returns the player
+ * @throws NotificationException exception thrown when invalid playerName
+ */
+fun String.notifyPlayerRequired(key: String): Player {
+    return Bukkit.getPlayer(this) ?: throw NotificationException(key)
+}
+
+