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Java Forum / General / March 2008What's the difference between "JDK" and "JRE"?
It seems both have a java.exe which can be used to execute the byte code(.class) but then jre does not have the javac compiler. > It seems both have a java.exe which can be used to execute the byte > code(.class) but then jre does not have the javac compiler. You basically answered your own question.  SignatureSabine Dinis Blochberger Op3racional www.op3racional.eu > It seems both have a java.exe which can be used to execute the byte > code(.class) but then jre does not have the javac compiler. Google is your friend http://www.google.com/search?q=jre+jdk+difference SignatureAndrea Francia http://www.andreafrancia.it/ >It seems both have a java.exe which can be used to execute the byte >code(.class) but then jre does not have the javac compiler. see http://mindprod.com/jgloss/jre.html http://mindprod.com/jgloss/jdk.html You need the JDK if you want to write your own programs. If you just want to run them, you can get away with the JRE. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com > It seems both have a java.exe which can be used to execute the byte > code(.class) but then jre does not have the javac compiler. Pretty much that is it. There are more development tools in the JDK than just javac, but that's the idea. JRE is just the runtime, for a user who wants to only run programs other write. The JDK is for programmers who need more tools, like javac. >> It seems both have a java.exe which can be used to execute the byte >> code(.class) but then jre does not have the javac compiler. [quoted text clipped - 3 lines] > user who wants to only run programs other write. The JDK is for > programmers who need more tools, like javac. It should be noted though that a few server products requires the JDK just for running, because they use stuff from tools.jar. Arne >It should be noted though that a few server products requires >the JDK just for running, because they use stuff from tools.jar. Java.exe -server lives in the JDK only. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com >> It should be noted though that a few server products requires >> the JDK just for running, because they use stuff from tools.jar. > > Java.exe -server lives in the JDK only. 1) No. C:\Program Files\Java\jre1.6.0\bin>java -? Usage: java [-options] class [args...] (to execute a class) or java [-options] -jar jarfile [args...] (to execute a jar file) where options include: -client to select the "client" VM -server to select the "server" VM 2) Even though most server apps uses the server VM, then it is perfectly valid to use server VM for client apps and client VM for server apps. Arne >> Java.exe -server lives in the JDK only. > >1) No. A while a go I did benchmarks with client and server. I found that the JRE version of java.exe did not understand -server. the system32 version of java.exe might be smart enough to use the JDK version if you use -server. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com >>> Java.exe -server lives in the JDK only. >> 1) No. [quoted text clipped - 4 lines] > the system32 version of java.exe might be smart enough to use the JDK > version if you use -server. As I showed then in the stuff you did not quote, then the java.exe in my JRE does understand (or at least claim to) -server. It is also very simple to use fc to verify that the java.exe in the JRE bin and the JDK bin are identical. Arne >It is also very simple to use fc to verify that the java.exe in the >JRE bin and the JDK bin are identical. that means little. They look in the registry ,load dlls, figure out which JDK/JRE to use etc. So the exact same executable can behave differently in different contexts. The most obvious example would be using an java.exe in a JRE uses that JRE where the one in system32 looks in the registry ot decide which JRE to use then loads that one. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com >As I showed then in the stuff you did not quote, then the java.exe >in my JRE does understand (or at least claim to) -server. I just did an experiment [F:\Program Files\Java\jdk1.6.0_05\jre\bin]java -server -jar E:\com\mindprod\converter\converter.jar which would have used the jre java.exe and it worked happily. You are correct. Now the question is, is this behaviour new in 1.6, or was it always thus and something threw me off earlier. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com >> As I showed then in the stuff you did not quote, then the java.exe >> in my JRE does understand (or at least claim to) -server. [quoted text clipped - 7 lines] > correct. Now the question is, is this behaviour new in 1.6, or was it > always thus and something threw me off earlier. C:\Program Files\Java\jre1.5.0\bin>java -? Usage: java [-options] class [args...] (to execute a class) or java [-options] -jar jarfile [args...] (to execute a jar file) where options include: -client to select the "client" VM -server to select the "server" VM C:\Program Files\Java\j2re1.4.2_02\bin>java -? Usage: java [-options] class [args...] (to execute a class) or java [-options] -jar jarfile [args...] (to execute a jar file) where options include: -client to select the "client" VM -server to select the "server" VM C:\Program Files\Java\j2re1.4.1_02\bin>java -? Usage: java [-options] class [args...] (to execute a class) or java -jar [-options] jarfile [args...] (to execute a jar file) where options include: -client to select the "client" VM -server to select the "server" VM Arne Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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