JRE 6 users need to download the special Java 6 build under the Files tab
This plugin allows admins to specify blocks to only be allowed to be broken with a specific tool via a configurable YAML config file. For example, an admin could make ores only able to be destroyed with a pickaxe. The plugin supports multiple item/block IDs as well as configurable messages.
enforce: '5': Any axe,271,275 '56' Iron or diamond pickaxe,257,278
5 represents wood (any data value), 56 equals diamond ore. The first text represents the message displayed to users (You must use tool: x). The other values are allowed item IDs to break the block. You can have as many of these as you like. See this wiki page for Item and block id values.
You can use /treload to reload the config file, and /tools on/off [player] to alter your own, or other players exemption from the enforcement.
This may help with approval and those looking to understand Java. It's not brilliant coding, and still needs some tweaking but you can see it here