java heap size error dex2jar android decompile solution?

i was working on a android project but my laptop was formatted so i lost all code but i had a signed apk of the file on my phone .. whenever i try to use dex2jar it stops converting mid way with this error. how can i increase the heap size or is there another way out. can i decompile an apk with the key it was signed with

C:~dex2jar>d2j-dex2jar --force
classes.dex
dex2jar classes.dex -> classes-dex2jar.jar
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at org.objectweb.asm.Type.getInternalName(Unknown Source)
    at com.googlecode.dex2jar.v3.V3ClassAdapter.searchEnclosing(V3ClassAdapt
er.java:179)
    at com.googlecode.dex2jar.v3.V3ClassAdapter.build(V3ClassAdapter.java:13
0)
    at com.googlecode.dex2jar.v3.V3ClassAdapter.visitField(V3ClassAdapter.ja
va:303)
    at com.googlecode.dex2jar.reader.DexFileReader.acceptField(DexFileReader
.java:603)
    at com.googlecode.dex2jar.reader.DexFileReader.acceptClass(DexFileReader
.java:439)
    at com.googlecode.dex2jar.reader.DexFileReader.accept(DexFileReader.java
:330)
    at com.googlecode.dex2jar.v3.Dex2jar.doTranslate(Dex2jar.java:84)
    at com.googlecode.dex2jar.v3.Dex2jar.to(Dex2jar.java:239)
    at com.googlecode.dex2jar.v3.Dex2jar.to(Dex2jar.java:230)
    at com.googlecode.dex2jar.tools.Dex2jarCmd.doCommandLine(Dex2jarCmd.java
:109)
    at com.googlecode.dex2jar.tools.BaseCmd.doMain(BaseCmd.java:168)
    at com.googlecode.dex2jar.tools.Dex2jarCmd.main(Dex2jarCmd.java:34)

Answer

Make a copy of the d2j-dex2jar.bat file, and edit it. Find the line that says this:

java -Xms512m -Xmx1024m -cp "%CLASSPATH%" 
            "com.googlecode.dex2jar.tools.Dex2jarCmd" %*

Change the -Xmx parameter to give yourself a larger maxheap size. Save it, and see if your modified BAT file works better. (There isn’t an elegant way to override the JVM settings in this script.)

---

Apparently … if you are using dex2jar-2.0, the file that you need to edit is d2j_invoke.bat.