Crash report is detailed below straight from the game. Have searched how to fix it but everything I do doesn't work. Have checked Java, have uninstalled and reinstalled to the latest version. Also uninstalled and reinstalled Minecraft. Have checked memory, have 4GB, so plenty there and nothing else is running at the same time. Please help.

---- Minecraft Crash Report ----
// Don't be sad. I'll do better next time, I promise!

Time: 21/09/15 4:12 PM
Description: Initializing game

java.lang.OutOfMemoryError: Java heap space
at bmi.a(SourceFile:230)
at bmh.b(SourceFile:130)
at bmh.a(SourceFile:77)
at bot.j(SourceFile:553)
at bot.a(SourceFile:139)
at bou.a(SourceFile:23)
at bnn.a(SourceFile:99)
at ave.am(SourceFile:448)
at ave.a(SourceFile:310)
at net.minecraft.client.main.Main.main(SourceFile:124)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Stacktrace:
at bmi.a(SourceFile:230)
at bmh.b(SourceFile:130)
at bmh.a(SourceFile:77)
at bot.j(SourceFile:553)
at bot.a(SourceFile:139)
at bou.a(SourceFile:23)
at bnn.a(SourceFile:99)
at ave.am(SourceFile:448)

– Initialization –
Details:
Stacktrace:
at ave.a(SourceFile:310)
at net.minecraft.client.main.Main.main(SourceFile:124)

– System Details –
Details:
Minecraft Version: 1.8.8
Operating System: Windows 7 (x86) version 6.1
Java Version: 1.8.0_60, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
Memory: 2270784 bytes (2 MB) / 1046937600 bytes (998 MB) up to 1046937600 bytes (998 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn256M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.8.8
LWJGL: 2.9.4
OpenGL: Intel(R) HD Graphics Family GL version 3.0.0 - Build 8.15.10.2291, Intel
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: No
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs: PureBDcraft 512x MC18
Current Language: English (US)
Profiler Position: N/A (disabled)
CPU: 8x Intel(R) Core(TM) i7-2630QM CPU @ 2.00GHz