Enable generics in blackberry jde 4.5.0

问题

When i compiled my application in blackberry it shows the following error. generics are not supported in -source 1.3 (use -source 5 or higher to enable generics) how to solve this

回答1:

Java 1.3 is barbaric and no one should ever have to suffer its indignities. Fortunately, there is a solution!

Generics, enums, changing return signature in overrides, and pretty much everything that makes java usable was introduced in java 1.5. (see http://en.wikipedia.org/wiki/Java_version_history). Fortunately, most of java 1.5 was designed to be backwards compatible and not require JVM / bytecode changes. (or maybe this was unfortunate, as it lead Java's implementation of generics to be much weaker than C#. just try creating a generic class with static methods / fields that use the generic parameter)

This IBM article does a good job of explaining the background: http://www.ibm.com/developerworks/java/library/j-jtp02277.html

But this JVM similarity allowed for creation of tools such as: http://retrotranslator.sourceforge.net/

This is the section from my Ant buildfile that calls retrotranslator:


 &lt java jar="${transformer.jar.exe}"
        fork="true"
        classpath="${epic-framework.dir}/tools/retrotranslator-runtime13-1.2.9.jar:${epic-framework.dir}/tools/retrotranslator-runtime-1.2.9.jar"
    args="-srcjar ${build.dir}/classes5.jar -target 1.3 -destjar ${build.dir}/classes5to3.jar"
 />

Run the converted jar through preverify.exe and then give it to rapc.exe and you will have a working Blackberry app written with Java 1.5.

Edit: I missed a key detail in my original post. In addition to being Java 1.3, the Blackberry class hierarchy is missing many classes that would normally be a part of a Java SE 1.3 JDK. The one you will hit first is StringBuilder -- javac transforms ("string" + "otherstr" + "blah blah") into StringBuilder.append("string").append("otherstr").append("blah blah"). That class doesn't exist on BB, so you break. However, BB has StringBuffer, so writing an adapter between the two is pretty easy. The one catch is that BB disallows apps from adding classes into java.*. This can be very effectively fixed in the build process: 1) build your app against Java 1.5 w/ java.lang.StringBuilder on the classpath, 2) string transform java.lang.Stringbuilder (and everything else in your compat shim) to live in com.mycorp.java.lang.StringBuilder and build it into a JAR file. 3) Use that JAR file w/ retrotranslator and retrotranslator will update all bytecode references to java.lang.StringBuilder so that they now point to com.mycorp.java.lang.StringBuilder. Now you have a java 1.3 compatible bytecode that can be run on a Blackberry.

If anyone is interested in this stuff, contact me. I could look into open sourcing the compat library I have.

回答2:

This is a limitation of J2ME, which uses a subset of the J2SE (no collections, reflection, etc.) and a Java language level of 1.3. Any code written for J2SE will most likely need to be manually ported.

回答3:

It seems the JDK5 is not yet supported.

Same question was asked on the blackberrry forum but about enum support:

回答4:

Sadly, the BlackBerry api is very behind in terms of Java versioning. There's no Generics, no Maps, no Enums - it's based around JDK 1.3.

I believe there is no way of enabling this feature within your BlackBerry app. If you find one, I'd be very interested to hear about it.

来源：https://stackoverflow.com/questions/3739080/enable-generics-in-blackberry-jde-4-5-0

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blackberry