I've been googling a lot for this and it seems easy, but it just doesn't work for me.
I want to include Twitter4j in my JAR in IntelliJ IDEA. I have put the twitter4j JAR into my /lib folder , specified it in Libraries,
specified it to compile in dependencies:
Dependencies
and specified to include it in artifacts.
In the final JAR, both twitter4j-stream and twitter4j-core are included:
Final JAR
Still, Java throws a NoClassDefFoundError when run.
(This is not Maven.)
Answer given by author of the question:
In the Artifacts, you have to choose "Extracted *.jar" instead of the
library.
I had similar error and the problem was that I did not write correctly the title in the command line: java title. Be sure that your title is equal to the program name written inside your program before it has been packed.
In public class title the title must be equal to the program name as well as to the name of jar archive.
(Obviously you can not use data files inserted in the JAR file with the CLASS file until the JAR file is unpacked...)
Related
The issue:
We have a jetty web-app, and in the application-code, I am trying to access a zip within a jar in classpath. Here's the jar in the libs folder:
/path/to/app/x.x.0-SNAPSHOT/apps/libs/my-model.jar
where my-model.jar is really just an empty folder with model.zip file inside it. If I extract this jar, I get johnsnow/mymodel.zip
My application code tries to access this zip as:
getClass().getResourceAsStream("johnsnow/mymodel.zip")
but of course, I don't get a proper handle to this resource and wind up getting a nullpointer exception. What am I doing wrong? Shouldn't I be able to access a file within a jar file in classpath using the getClass().getResourceAsStream() method?
Footnote:
Because model.zip was too large, we decided against shipping it with the code base. Thus we pushed it into a nexus repository, and reference the jar via a gradle compile dependency as follows:
compile "com.company.group.nlp:my-model:1.0#jar"
The fact that building the distribution pulls this jar, and puts it in apps/libs tells me that gradle does its part (of downloading the dependency to a classpath). The issue remains that I can't seem to find a way to access mymodel.zip inside my-model.jar
Try adding a slash to the file path:
getClass().getResourceAsStream("/johnsnow/mymodel.zip");
It will tell java to start looking for the class from the root folder, not from the current class package.
Both class.getResource(FILE_NAME) and class.getClass().getClassLoader().getResource(FILE_NAME) run perfectly inside my eclipse but the same code getting failed to locate the file which is inside the jar file, when run as an executable jar in windows machine.
I have gone through all related links available for this problem (well, not exactly the same issue but 90% in sync), asked for solution but no reply came from any of those posts, so I'm posting my issue as a separate question hoping for help on this.
In total, 4 cases I have ran to resolve but none worked so far and I'm out of ideas now.
class.getClass().getClassLoader().getResource("/resources/readme.txt");
class.getResource("/resources/readme.txt");
class.getClass().getClassLoader().getResource("resources/readme.txt");
class.getResource("resources/readme.txt");
Ouf of all the above 4 cases, only 2 cases ran successfully in eclipse which are as mentioned below.
class.getResource("/resources/readme.txt");
class.getClass().getClassLoader().getResource("resources/readme.txt");
The other 2 cases just throwing me Exception in thread "main" java.lang.NullPointerException
Coming to the executable jar, all 4 cases are throwing me the Exception in thread "main" java.lang.NullPointerException.
So I have created a folder named resources where my jar is residing and placed my files inside this folder and ran the jar. Now the jar is running without any issues referring to the files inside the resources folder I created. So wherever I run this jar (windows, linux etc.,) I need to create a resources folder and place my files under the folder. Now the question is, can it be possible to make my jar refer the resources folder which is inside the jar itself?
Any help on this is much appreciated!
To get your txt file:
File yourFileIsHere = new File("resources/readme.txt");
Where put your file?
In the same location of your jar, example:
myapp/yourjar.jar
myapp/resources/readme.txt
If you want read file inside of your "src" folder:
InputStream yourInputStream = new YourClass().getClass().getClassLoader().getResourceAsStream("readme.txt");
If you are using Spring:
org.springframework.util.ResourceUtils.getFile("classpath:readme.txt")
Otherwise:
import com.google.common.io.Resources
byte[] byteSource = Resources.asByteSource(Resources.getResource("readme.txt")).read()
method class.getClass().getClassLoader().getResource() may take 3 prefixes: url:, classpath: and file: each prefix tells what is your base of search. If you want to search inside your jar use classpath: prefix. That tells your classloader to search everywhere within your classpath. Here is one example how to deal with it with Spring tools. Look also at ResourceLoader class in Spring
My code has gotten quite large and so I've decided to build a runnable JAR to see how it's done. I probably should've tried sooner because I'm getting 2 different errors related to the project structure, first is the "no main manifest attribute error" when trying to run the JAR from command prompt. Double-clicking the JAR does nothing (Win7). The second issue is related to the FXMLLoader explained lower down.
I followed the steps here to build the JAR, which involved moving all Maven files into the JAR directory. The compiled JAR gave me the manifest error, so I followed this which adds a Maven plugin in my pom.xml file. The error might be caused by a wrong naming convention with the line <mainClass>com.primary.Drag</mainClass> where primary is the package and Drag is my Drag.java file (class) which has the main method.
Inititally I was using the default package but read that this is not recommended for larger projects, so I put all my files into "primary". Here is my current hierarchy as shown in IntelliJ:
The problem is that ever since I created the "primary" package, I can no longer even compile the program via IntelliJ, let alone build a runnable JAR. This is due by the second error I mentioned, which is java.lang.IllegalStateException: Location is not set. on this line within primary/Drag.java:
FXMLLoader loader = new FXMLLoader(getClass().getClassLoader().getResource("firstlaunch.fxml")); It used to work with the default package, but not anymore.
I tried replacing firstlaunch.fxml with /primary/firstlaunch.fxml and /resources/firstlaunch.fxml (with and without moving resources into primary package) but no luck.
3 Related Questions:
Is my project structure incorrect?
How do I reference the fxml file from the primary package?
Is this what I should write in Maven's mainClass tags? <mainClass>com.primary.Drag</mainClass>
Is my project structure incorrect?
Answer:
Your package name should be like com.primary.******
How do I reference the fxml file from theprimary package?
Answer:
Always make sure that you are trying to load firstlaunch .xml from the class which is located in same package where that xml is kept. Means class which you wrote the loading code and xml file should be in same package
Is this what I should write in Maven's mainClass tags?com.primary.Drag
Answer:
If you package name corrected to com.primary , your main class Drag will correctly added by maven
I took the java implementation of the Factual API (reference http://developer.factual.com/) and made a JAR file for factual. I did this by opening a new project in eclipse with the factual java files and then exporting to a new jar file.
I put that jar file in my coldfusion installation's /WEB-INF/lib/ folder.
After restarting Coldfusion, I tried to create a new cfobject like so
<cfscript>
// Initialize the Java class.
factualClass=CreateObject("java", "src.main.java.com.factual.driver.Factual");
</cfscript>
I get an error indicating that it cannot find the Factual class.
Can anybody give me some guidance?
(Summary from comments)
It sounds like you may be exporting the source files ie *.java rather than the compiled class files, ie *.class. In the Jar Export wizard, be sure to select the "Export generated class files and resources" option. (To automatically compile the project sources before expi, enable the setting: JAR packaging > Build projects if not build automatically option). If you prefer you can also find pre-compiled jars in the MVN repository.
put that jar file in my coldfusion installation's /WEB-INF/lib/
folder.
CF10+ also supports dynamic class loading via a new application level setting THIS.javaSettings.
// Initialize the Java class.
factualClass=CreateObject("java", "src.main.java.com.factual.driver.Factual");
Just as a point of interest, src/main/java/ is not actually part of the libary class name. It is a standard directory structure used in Maven projects. It is probably included when exporting the sources, but not the compiled classes.
You can always verify the correct path and class name either by examining the API ie javadocs or by viewing one the source files. Package declarations are always at the top of the source file, such as on line 1 of src/main/java/com/factual/driver/Factual.java:
package com.factual.driver; // ie "com.factual.driver"
.. and the class declaration on line 39.
public class Factual { // ie "Factual"
Combined that gives you the exact (case-sensitive) path to use with createObject:
factualClass=CreateObject("java", "com.factual.driver.Factual");
I'll try to illustrate the problem as simple as I can.
I have a JAR file, which I extracted using Winrar. (The jar file contains an open source android library).
I want to modify this JAR file by adding a new class to the library.
So here are my steps:
First, I created a class using Eclipse and set the package name same as the android's library package name.
Second, I copied this java File to the folder of the other java files in the library.
Third, I tried to compile the JAVA file via the CMD using javac.
The path of the new java file and the other .JAVA and .CLASS files of the library is: C:\com\example\core\
The name of the new java file would be: "MyNewClass.java"
The command I run via the CMD is: javac C:\com\example\core\MyNewClass.java
But, during the compilation I get many errors saying: Cannot find symbols.
I've been looking up for a solution of this problem but couldn't figure how to solve it and make the new JAR File having another class that I created seperately.
What am I missing?
As per earlier comments:
Rather than trying to modify the JAR, you can get access to the full source code of the Universal Image Loader library by cloning the repository using git or hitting "Download ZIP" on the righthand side of the page you linked.
Once you have the source, import the library in your IDE. From there on you'll be able to build the whole thing from scratch, make any adjustments/modifications you like, etc.
Your classpath might be wrong or there might be some mistake in package name.
When a Java program is being compiled the compiler it creates a list of all the identifiers in use. If it can't find what an identifier refers to it cannot complete the compilation. This is what the cannot find symbol error message is saying, it doesn't have enough information to piece together what the Java code wants to execute.
Try:
javac -cp com/* C:\com\example\core\MyNewClass.java
That should make the compiler aware of all the other classes under com/...