I got this error and I don't know why... (Waiting for answer)

...I just created my first "plugin".
I watched a basic YouTube tutorial on what I'm supposed to do.
I copied the code exactly and did what he did, but got this error.

[SEVERE] Could not load 'plugins\firstplugin.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: me/frozenpoptart/WarpAll/WarpAll : Unsupported major.minor version 51.0
at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:155)
at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:305)
at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:230)
at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:222)
at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:198)
at net.minecraft.server.ServerConfigurationManagerAbstract.<init>(ServerConfigurationManagerAbstract.java:50)
at net.minecraft.server.ServerConfigurationManager.<init>(SourceFile:11)
at net.minecraft.server.DedicatedServer.init(DedicatedServer.java:105)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:380)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)
Caused by: java.lang.UnsupportedClassVersionError: me/frozenpoptart/WarpAll/WarpAll : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$000(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:41)
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:29)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:144)
... 9 more

 

Change your java version in the plugin to java 1.6?

 

How would I do that?

I'm clueless. xD

Help?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

The version of Java the server is running should always match that of what the plugin is compiled against. If you're running jre6 on your server, compile against jre6. jre7 on the server, compile against jre7, etc..

 

Did you refresh the project before exporting?

 

Go to http://www.java.com/ and download the latest java version.

 

No. the latest java version is 7u6 which is not what the OP wants to compile against if the server is running 6. Also even with a 7JDK you can compile for 6.

 

Or (if you have any sort of control on your server) you could use JRE7. If you are using OpenJDK7, you might have to set the environment variable $JAVA_VERSION to 1.7

Code:text

//bash
export JAVA_VERSION=1.7
//tcsh
setenv JAVA_VERSION 1.7

Don't quote me on the syntax... I only use tcsh. If you plan on distributing the plugin, it is best to compile for Java 6, since many servers are locked in to Java 6.

That is true, but I've heard that you can run into problems with that, it is best to compile against JRE6. If I remember correctly, javac warns you if you compile for a different version than the one in your boothclasspath. If you use Eclipse it is easy because Eclipse handles everything.