Generate Minecraft Bukkit Random Blocks?

I want in my plugin a system, that e.g. At each block of earth the 30% chance is that just above the ground block spawn a wooden block. (So just that at random 30% of all earth blocks a wooden block directly over spawned) Thank you in advance in advance, I'm also happy only about approaches etc.

Well, you loop through all the blocks you want to talk to and make random from 1 to 10 and run it when the generator spits out 1 2 or 3. Rough attack the rest I leave you

There's no program that is really random as it only takes variable as time goes by if you spit something fast the same could come out

Exactly what you say, "… You loop through all the blocks through which you want to address…" that's what I do not get: / if you could send me a wiki page or nen example code that would be very helpful

Researching this is your job. If you want to learn something you have to do it yourself. Nen approach you have schonmal. If you can't stop learning, learn a few basics

Then you should improve your Google skills I've found directly after a search. You have to find this yourself or you will not learn anything

You also know what to look for._. Could you at least then tell me the search term?