I am developing an API(.jar) to be used with Android App, I have constrain on size of .jar file after build.
I am using several dependent libraries(.jar) files, but not completely; hardly 5-6 class files from 200.
How can I use the selected .class files from libraries and dependent .class files?
Proguard automatically does this.
Configure proguard via Gradle:
http://proguard.sourceforge.net/manual/gradle.html
I'm not quite sure if this is what you are looking for but you can use -cp to run a specific class in your jar file
example:
java -cp myjar.jar package1.class1
Related
I'm currently trying to compile my project which would include two external libraries.
json-simple.jar and mysql-connector-java-5.1.42-bin.jar
At the moment I compiling my program and the problem is that i need to include these libraries in the classpath of created compiled project, but i do need only that these libraries would inside .jar project compiled file and i can simply run .jar file and make it work withuot including classpaths or something like that.
Is that possible, don't have idea how.
Yes, it is possible.
I'll help you a bit:
How to make an executable jar file?
Basically unpack the files from the libraries into the folder with your compiled classes (you know how to compile them, right?) then prepare a MANIFEST.MF, put it the folder with all these classes, then create a jar as explained in the answers under the link (jar cfm jarexample.jar jexample.mf *.class). If you have any problems then read the documentation of the commands like jar and javac.
Have fun!
I just need a simple environment of .class and .java files in a single folder so that I can execute java files later on using "java xx" in command line without adding any extra syntax. I'm not planning to use packages or sub-directories in my project and I won't be executing any files directly from eclipse either.
You could create a executable jar file and run it from command line using:
java -jar MyApplication.jar
Here is the link to create an executable jar file from eclipse:
How to create an Executable jar file
I think you are looking for this:
Create new project->Java Project->In the Project Layout section change to 'User project folder as root for sources and class files' (using Eclipse Kepler, it should be similar in other versions of Eclipse).
But keep in mind that it might become a mess after some time.
I've downloaded a new api for Java that accesses excel files, but am unsure on how to install it so that it can be imported for use in my program. Help is appreciated. Thanks
To the point: just put it in the classpath.
A classpath is basically a collection of disk file system paths to a root folder where all classes are located like /path/to/package/root and/or paths to the JAR file itself like /path/to/file.jar. You can specify multiple paths in the classpath by a separator character. In Unix based systems like OS X the separator character is the colon : (on Windows it's the semicolon ;).
How and where to specify the classpath depends on how you're compiling and executing the program.
If you're using plain javac to compile the program, then use the -cp argument to specify the compile time classpath. Or if you're using an IDE, then add it to the project's Build Path (which covers both the compile time and runtime classpath).
If you're using java to execute the program as a simple .class file, then use the -cp argument the same way. If you're using java -jar (or doubleclicking the file in some platform specific UI explorer) to execute the program as an executabele .jar file, then you need to specify it in Class-Path entry of the JAR's MANIFEST.MF file. This one can be relative to the JAR file's location.
You don't really have to "install" it - you just have to put it inside the Classpath. For example, if you're using Eclipse, you can right-click on your project, select something like "build path"->"configure build path", then libraries.
That depends on the tools you are using for development. Basically it will have to be included on your classpath for your IDE project for development, and in your runtime classpath at deployment time.
How to accomplish this in development is specific to your project configuration, IDE and how you store dependent jar files in your development environment (i.e. shared lib directory, maven, project lib folder ...).
We used an external library, specifically jmf.jar (Java Media Framework), for our java application which relies on images captured from the webcam. However, when we tried to package the application into a jar file, the application runs but once we try to access/open the webcam nothing happens.
We are using Eclipse and we used its export feature to create the jar file.
Does anybody know how to solve this?
Did you think to include jmf in the manifest of your jar ? See this link for more explanations here
You don't just need to export your project into a jar file; you need to create an "executable" jar file. This means that the manifest of the jar file is edited appropriately so that the classpath includes all required dependencies and the main class is set correctly.
In recent versions of Eclipse you can use the Runnable JAR File Export Wizard. Have also a look at the Fat Jar Eclipse Plug-in.
If you are using JMF you’ll need to include jmf.jar and jmf.properties in the same directory as the executable jar
I am using Netbeans IDE for a java project. In this project i need a jar file "htmlunit-2.6.jar".
I have included this jar file in the project libraries folder. I have instantiated one of its class "WebClient" but this class needs other classes of "commons-httpclient-3.1.jar" file.
Now I have also included "commons-httpclient-3.1.jar" file in the project libraries folder. But when I compiled my source file, it throws
ClassNotFoundException: org.apache.commons.httpclient.auth.CredentialsProvider
Kindly tell me how to handle this situation when one class in one jar file needs other classes in other jar file.
Simply put the required jar files on the classpath at compile-time and it should work. If you were doing it from the command-line then it would look like this:
javac -cp jar1:jar2 my.Application
If you are using NetBeans then you need to tell NetBeans that both of the JARs are on your classpath. It will be definable in a Project > Properties wizard as described here and also here from the tutorial
The ClassNotFoundException tells you that your libraries have some dependencies that you don't have included in your classpath at runtime. Your source is OK, because if you have used something not available, NB will tell you this at compile time (or before when editing).
So, welcome in the "dependency hell" of Java. For small projects you will be able to check all dependencies by hand with readme files, docs, etc and put them in the project config as oxbow_lakes said. For bigger things look at maven. It will do (most) everything for you !
(Maven is available in NB6)