Problem z gui

[MieciuXD1234]

Witam chciałbym się dowiedzieć jak dodać takie coś że jak to się kliknie w GUI to drop jest wyłączony a jeżeli drugi raz to wraca z powrotem że jest włączony. Zrobiłem coś takiego

 

ItemStack d1 = new ItemStack(Material.DIAMOND, 1, (short) 95);{

ItemMeta im = d1.getItemMeta();

im.setDisplayName("§6§lSiema");

im.setLore(Arrays.asList("§6§lSiema"));

d1.setItemMeta(im);

inv.setItem(10, d1);

 

ItemStack d2 = new ItemStack(Material.DIAMOND, 1, (short) 95);{

ItemMeta im = d2.getItemMeta();

im.setDisplayName("§6§lSiema");

im.setLore(Arrays.asList("§6§lSiema"));

d2.setItemMeta(im);

inv.setItem(10, d2);

 

 

if(Utils.drop.get(player.getName()) == true)

inv.setItem(1, d1);

else

inv.setItem(1, d2);

 

@Edit

 

Teraz mi błąd w konsoli wyskakuje nie wiem czemu

 

 org.bukkit.command.CommandException: Unhandled exception executing command 'kamien' in plugin HCland-Drop v1.0

        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:196) ~[craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at org.bukkit.craftbukkit.v1_7_R1.CraftServer.dispatchCommand(CraftServer.java:542) ~[craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at net.minecraft.server.v1_7_R1.PlayerConnection.handleCommand(PlayerConnection.java:932) [craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at net.minecraft.server.v1_7_R1.PlayerConnection.a(PlayerConnection.java:814) [craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at net.minecraft.server.v1_7_R1.PacketPlayInChat.a(PacketPlayInChat.java:28) [craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at net.minecraft.server.v1_7_R1.PacketPlayInChat.handle(PacketPlayInChat.java:47) [craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at net.minecraft.server.v1_7_R1.NetworkManager.a(NetworkManager.java:146) [craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at net.minecraft.server.v1_7_R1.ServerConnection.c(SourceFile:134) [craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at net.minecraft.server.v1_7_R1.MinecraftServer.u(MinecraftServer.java:655) [craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at net.minecraft.server.v1_7_R1.DedicatedServer.u(DedicatedServer.java:250) [craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at net.minecraft.server.v1_7_R1.MinecraftServer.t(MinecraftServer.java:545) [craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java:457) [craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:617) [craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

Caused by: java.lang.NullPointerException

        at maxpayne.drop.hcland.DropGui.openGUI(DropGui.java:53) ~[?:?]

        at maxpayne.drop.hcland.DropGui.onCommand(DropGui.java:27) ~[?:?]

        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[craftbukkit-1.7.2.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]

        ... 13 more

[MieciuXD1234]

@ref

[ShakeeTeFau]

Czym są linijki 53 i 27?