[18:08:50 INFO]: Error could not Connect to db jdbc:mysql://localhost:3306/minecraft?allowMultiQueries=true: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
[18:08:50 WARN]: java.lang.NullPointerException
[18:08:50 WARN]:        at com.ginger_walnut.sqboosters.database.SQLDatabase.readData(SQLDatabase.java:54)
[18:08:50 WARN]:        at com.ginger_walnut.sqboosters.database.DatabaseInterface.updateLocalCopy(DatabaseInterface.java:38)
[18:08:50 WARN]:        at com.ginger_walnut.sqboosters.DatabaseChecker$1.run(DatabaseChecker.java:33)
[18:08:50 WARN]:        at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftTask.run(CraftTask.java:71)
[18:08:50 WARN]:        at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:350)
[18:08:50 WARN]:        at net.minecraft.server.v1_9_R1.MinecraftServer.D(MinecraftServer.java:729)
[18:08:50 WARN]:        at net.minecraft.server.v1_9_R1.DedicatedServer.D(DedicatedServer.java:400)
[18:08:50 WARN]:        at net.minecraft.server.v1_9_R1.MinecraftServer.C(MinecraftServer.java:660)
[18:08:50 WARN]:        at net.minecraft.server.v1_9_R1.MinecraftServer.run(MinecraftServer.java:559)
[18:08:50 WARN]:        at java.lang.Thread.run(Unknown Source)