java.lang.NullPointerException: null | Bukkit.getPluginCommand Error, Spigot API 1.16 using

Question

Here I implemented my commands:

Bukkit.getPluginCommand("fw").setExecutor((CommandExecutor)new FireworkCMD());
Bukkit.getPluginCommand("armor").setExecutor((CommandExecutor)new LeatherarmorCMD());
Bukkit.getPluginCommand("f").setExecutor((CommandExecutor)new FlyCMD());
Bukkit.getPluginCommand("glow").setExecutor((CommandExecutor)new GlowCMD());
Bukkit.getPluginCommand("team").setExecutor((CommandExecutor)new TeamCommand());
Bukkit.getPluginManager().registerEvents((Listener)new MainListener(), (Plugin)this);
Bukkit.getPluginManager().registerEvents((Listener)new INventoryListener(), (Plugin)this);
Bukkit.getPluginCommand("gm").setExecutor((CommandExecutor)new GMCMD());

But it comes that error using Paper 1.16:

at de.universenetwork.vipfeatures.Vipfeatures.onEnable(Vipfeatures.java:19) ~[?:?]
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:263) ~[patched_1.16.5.jar:git-Paper-794]
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:370) ~[patched_1.16.5.jar:git-Paper-794]
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:500) ~[patched_1.16.5.jar:git-Paper-794]
at org.bukkit.craftbukkit.v1_16_R3.CraftServer.enablePlugin(CraftServer.java:518) ~[patched_1.16.5.jar:git-Paper-794]
at org.bukkit.craftbukkit.v1_16_R3.CraftServer.enablePlugins(CraftServer.java:432) ~[patched_1.16.5.jar:git-Paper-794]
at net.minecraft.server.v1_16_R3.MinecraftServer.loadWorld(MinecraftServer.java:599) ~[patched_1.16.5.jar:git-Paper-794]
at net.minecraft.server.v1_16_R3.DedicatedServer.init(DedicatedServer.java:298) ~[patched_1.16.5.jar:git-Paper-794]
at net.minecraft.server.v1_16_R3.MinecraftServer.w(MinecraftServer.java:1074) ~[patched_1.16.5.jar:git-Paper-794]
at net.minecraft.server.v1_16_R3.MinecraftServer.lambda$a$0(MinecraftServer.java:291) ~[patched_1.16.5.jar:git-Paper-794]

Answer 1

You seems to don't have declared the commands in your plugin.

You should declare commands in your plugin.yml file like that :

commands:
  fw:
  f:
  armor:
  glow:
  team:

Then, in your onEnable() method, do like that :

getCommand("fw").setExecutor(new FireworkCMD());
getCommand("armor").setExecutor(new LeatherarmorCMD());
getCommand("f").setExecutor(new FlyCMD());
getCommand("glow").setExecutor(new GlowCMD());
getCommand("team").setExecutor(new TeamCommand());

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