Creating a DEX file from Java source code

Question

I have searched extensively on the web for a comprehensive guide to creating an Android DEX file (Java Dalvik bytecode) using the Android SDK DX tool.

My aim is to create a Jar file that contains DEX byte code which can be loaded by an application at runtime.

To create the Jar file I have been following these steps:

1. Java source code containing a public class (Name.java)
2. Compile .java file from step 1 into .class file using javac Name.java
3. Created a Jar file from the class file. jar cvf output.jar name.class
4. Use the dx tool to convert class file into classes.dex. ./dx --dex --output=classes.dex output.jar
5. Use aapt to repackage the classes.dex file with the jar file.

So far I have managed to make it to step 4, which is where I am experiencing issues. When running the dx tool, I get the following error:

UNEXPECTED TOP-LEVEL EXCEPTION:
java.io.FileNotFoundException: /home/del/Desktop/AndroidJarBuilder/output.jar (No such file or directory)
    at java.util.zip.ZipFile.open(Native Method)
    at java.util.zip.ZipFile.<init>(ZipFile.java:215)
    at java.util.zip.ZipFile.<init>(ZipFile.java:145)
    at java.util.zip.ZipFile.<init>(ZipFile.java:159)
    at com.android.dx.cf.direct.ClassPathOpener.processArchive(ClassPathOpener.java:244)
    at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:166)
    at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:144)
    at com.android.dx.command.dexer.Main.processOne(Main.java:632)
    at com.android.dx.command.dexer.Main.processAllFiles(Main.java:510)
    at com.android.dx.command.dexer.Main.runMonoDex(Main.java:280)
    at com.android.dx.command.dexer.Main.run(Main.java:246)
    at com.android.dx.command.dexer.Main.main(Main.java:215)
    at com.android.dx.command.Main.main(Main.java:106)
1 error; aborting

I wonder if anyone has experienced this problem before, i could not find any answers on Stack Overflow, and the rest of the web did not provide me with any solutions.

Thanks in advance.

Harpoon

The error is pretty clear that "output.jar" doesn't exist. – Tantara

yes it is pretty clear. However output.jar does in fact exist. – Harpoon

I wouldn't run the dx command on output.jar if output.jar wasn't present would I! – Harpoon

The only way I'm aware of to get that exception is if the file doesn't exist, or the user that dx is running as doesn't have the right permissions on the file/containing directory/etc. – Tantara

Answer 1

Turns out the output of the jar command needs to be the same as the name of the class.

Renaming output.jar to Name.jar seemed to resolve the issue.

Harpoon

This makes no sense. The name of the jar is arbitrary, and a jar typically contains many classes. – Tantara