Android Question UNEXPECTED TOP-LEVEL ERROR:java.lang.OutOfMemoryError: Java heap space

when i compiling my project with debug mode,happen following error,No error if i delete a activity module and compiling project. why?
my project module quantity:
Activity Module 67
Class Module 11
code module 3
Sercice module 3

parsing code. 1.21
Compiling code. 1.06
Using existing AndroidManifest.xml.
(Project - Do Not Overwrite Manifest option is checked)
AndroidManifest-Example.xml file will be created instead.
Compiling layouts code. 0.14
Generating R file. 0.21
Compiling generated Java code. 4.67
Convert byte code - optimized dex. Error
UNEXPECTED TOP-LEVEL ERROR:
java.lang.OutOfMemoryError: Java heap space
at com.android.dx.rop.code.RopMethod.calcPredecessors(RopMethod.java:153)
at com.android.dx.rop.code.RopMethod.labelToPredecessors(RopMethod.java:95)
at com.android.dx.dex.code.RopTranslator.pickOrder(RopTranslator.java:352)
at com.android.dx.dex.code.RopTranslator.translateAndGetResult(RopTranslator.java:212)
at com.android.dx.dex.code.RopTranslator.translate(RopTranslator.java:106)
at com.android.dx.dex.cf.CfTranslator.processMethods(CfTranslator.java:293)
at com.android.dx.dex.cf.CfTranslator.translate0(CfTranslator.java:134)
at com.android.dx.dex.cf.CfTranslator.translate(CfTranslator.java:87)
at com.android.dx.command.dexer.Main.processClass(Main.java:487)
at com.android.dx.command.dexer.Main.processFileBytes(Main.java:459)
at com.android.dx.command.dexer.Main.access$400(Main.java:67)
at com.android.dx.command.dexer.Main$1.processFileBytes(Main.java:398)
at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:135)
at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:191)
at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:123)
at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:191)
at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:123)
at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:191)
at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:123)
at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:191)
at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:123)
at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:109)
at com.android.dx.command.dexer.Main.processOne(Main.java:422)
at com.android.dx.command.dexer.Main.processAllFiles(Main.java:333)
at com.android.dx.command.dexer.Main.run(Main.java:209)
at com.android.dx.command.dexer.Main.main(Main.java:174)
at com.android.dx.command.Main.main(Main.java:91)
Optimized dexer failed. Switching to Standard dexer.