Minecraft Has Ran Out Of Memory???!!

Put the summary of the bug you're having here

What I expected to happen was...:
My Minecraft game would open up on the menu scren and let me play it.

What actually happened was...:
On the MOJANG loading screen it said: Minecraft could not continue for it has ran out of memory.

Steps to Reproduce:
1.I clicked the Minecraft icon
2. It was loading the MOJANG and then it said: Not Responding
3. Soon after it said: Minecraft could not continue for it has ran out of memory.