Why does minecraft keep running out of memory and how can it

whoops clicked wrong thread

Yeah but, if I haven't got the ram to handle the needed memory theres no point in it.

Giga Hertz and a good graphics card is what you need. lotsa RAM is just a bonus

You need at least 4GB of physical ram and a semi good graphics card to run minecraft properly. Running the game in the browser will automatically give you trouble due to modern browsers eating up 200 - 400k worth or memory by default. Running youtube, facebook or anything else in open windows compounds the effects.

I expanded mine to 5 GB from 800 MB

Get more physical ram. Minecraft can Automatically allocate more ram.

when i type in javaw it says it doesnt recognize java commands

i dont use mac

You will need to do a google search on it, this search should contain cmd if you are using a windows pc. I don't know about macs.

and how do i allocate because my computer doesnt recognize java commands

you have to much worlds in single memory

You will need to allocate some more ram to minecraft, this used to happen to me a bit, but then I did this and I haven't seen the problem since. This only works if you are playing the downloaded version of minecraft. If you are playing in your browser then I can't help you other than telling you to download the game, sorry.

If you are indeed playing the downloaded version then all you need to do is find a tutorial on google and you will be in the clear. You will need to use cmd (the computer programing program ) so follow instructions of a reliable source exactly or you could damage your computer.