I'm fresh to Java and cannot get this right.
I've got only a .java file from a Java study book, that represents a Java project. There seems to be no option to input such file from Netbeans interface, that would automatically compile corresponding class and enable project to run.
I've spend a long time to figure this out, copying files manually, changing the automatically created class names and packages, moving this around - but I don't find a solution.
If someone can help - this will be great.
Pawel
It seems the issue was following. .java file should be placed in "src" directory within the Project folder, rather than straight in the Project folder.
So if say "Project" is one's destination folder, then one can:
choose from menu: New Project-Java-Java project from existing resources - indicate path to the ...\Project folder
the next step is to choose "Source Packages Folders" and here the path should lead to ...\Project\src .If the file .java is correctly placed there, the creator will indicate below that .java file is included to the project
If the code is right after finishing the creator and compiling it we get a compiled class Project.class and we can run it :)
Not sure if there is some work around to this in NetBeans, as it's not super intuitive, but I might not have found a better option.
I too was looking for File > "Import File", because there is an "Import Project" option. It appears dragging and dropping the java file into Source Package is just as easy. :)
Related
I have a question, perhaps it was already answered, but i didn't manage to find it and I appologize if the solution already exists (let me know if it is before deleting my thread).
Problem is:
I have created a program on another PC and exported it from eclipse as a .jar file. It works on my main PC when I double click on it but when I import it in Eclipse I can't find the .java file. So i can't edit it.
What I have done so far:
In eclipse I have created a new empty project
I have right clicked,import, archive file, selected the .class files that eclipse sees, but when I am in the Project Explorer in Eclipse I can't find the .java file where the main is. I mean I can click run as a program and it works, but there is no .java file, only .class files. What am I doing wrong?
That cranes.class should be cranes.java. At least on my other PC it is.
Program works fine, but I can't edit it on my main PC. What am I doing wrong?
Thanks and best regards
You need to select the Export Java source files and resources option while creating the jar file and then your Java files will be available on importing the project from the jar file.
This is similar to how you use other libraries. You depend on the Jar file which contains class bytecode (compiled) of java code. You can't edit any of such files directly in the project you are using it. Thought you can always extends functionalities in your current project using simple inheritance concepts.
If you think such functionalities are trivial you should prefer to change in the original project rebuild the jar and use the newer version of jar.
However if you feel similar things for 3rd party library you can
always make changes after taking fork from those library source
code (if open source) and build and use your own version or go
ahead and raise pull request if you are confident about your
changes.
Mostly when you build a jar file, all you have in it are .class files; these are the result of compiling .java files, and so are not editable with text editors.
You CAN create a jar file that contains .java (also known as source) files, and even a jar file that contains both .java and .class files, but if you ask eclipse to create a jar file, by default it is just going to put .class files and files from resource folders in it, not .java files.
Assuming from the question, the jar is a library created by OP, by compiling java files into class files and packing/exporting them. Although the class files can't be edited in any IDE, they can be de-compiled into Java files by using third-party applications.
I personally use IntelliJ for this de-compiling source files authored by me
Note: Although this gives OP the desired functionality, it may lead to violations if the classes are Copyrighted.
As IntelliJ states, they neither encourage nor discourage de-compiling class files and the decision is purely to the user's discretion.
EDIT: It is always recommended to use the original source files for editing. Try to host them on git so that it may be retrieved anytime required
It may be simpler to not use eclipse but jar/zip/tar your project directory on the one computer and simply extract it onto the other, then open that folder as a new project in Eclipse.
Best is the suggestion from #SanjayBharathi to use git and clone the repo on your other machine.
Recently I worked on a project on a mac, using eclipse. When I was done with the project I copied certain .java files and their corresponding .class files onto a USB drive and brought it to my personal computer. When I try to use the import feature on eclipse and import everything, my main method is not recognized by eclipse. It will work if I create a new eclipse "class" by the name I have in the program and copy paste the code. I have many classes so I can not do this for each one. Is there any way for me to change all .java/.class files into files that will be read by the system?
Thanks
An eclipse project contains a lot of meta information. Just open the project directory in a file browser, and have a closer look. There are files like .classpath for example.
When you just copy your source code, you leave all the meta information behind!
You should either copy the complete project directory, or simply use the export task to create a ZIP file of your project. (to later import that in other systems).
There is one other way you can do this. Just create a new project with the SAME EXACT PROJECT NAME that you did at school or wherever. After you create your project, go to your file explorer and navigate to the following place:
<"Directory to work-space">/<"Project Name">/src/
For ex: in Windows, it is Generally:
C:/Users/your_name/workspace/projectName/src
In here, copy all your ".java" files.
Now go to eclipse, right click on your project and hit refresh. You will find all your .java files there. Right-click on your project and hit "Run"->"Run as a Java Project". It should run! hope this helps.
PS: You do not need your class if you are executing it in Eclipse. Eclipse will create its own class files.
I'm trying to export a small program that I have made in Eclipse Indigo today to an executable, however, every time I do so one of two problems occur. The program uses one resource which I was hoping to put inside of the JAR but Eclipse will not put in the executable jar no matter which option I tick when I export or which folder the resource is in - the first problem!
The second problem is that whenever I tell eclipse to "Extract required libraries into generated JAR" I receive the following error when I double click on the executable Jar:
Could not find the main class: main.Launcher. Program will exit.
I don't suppose that the second problem is too much of an issue at the minute but the first one is extremely frustrating so I would appreciate any help or advice. Thanks in advance.
(Strangely, and even more frustrating, if I go through the same process with a project I made a while ago with a previous version of Eclipse it works perfectly.)
The folder structure of the project is as follows:
In the project folder there are the following directories .settings, bin, src as default. I have put the resource, which is a png in the bin folder but I have also tried it in the src folder.
Can you give some details?
What is the structure of your eclipse project?
Of what type is the resource?
More important where in the project structure resides the resource file?
Is the folder of that resource file included as a source folder ? (seems to be a prerequiste to get exported to the jar)
Is it copied over to the bin folder when the project is built?
Many Thanks
Michael
Update:
I have built a very simple java project 1 Java class with a main method and put a sample png file in the source folder. I refreshed the project to have the png visible in the project, then I cleaned the project to have it build again, then I ran the Main class inside eclipse. This will give you a run configuration when exporting throught the wizard. Thereafter I exported the complete project as "runnable jar", selected the run configuration and selected "Copy required libraries in a sub-folder next to the generated JAR". The png was included and the Main class was found. The executable JAR could be executed.
(Environment: Eclipse Indigo R1, Ubuntu, JDK 6)
You might want to play through the complete sequence of steps I went through. Maybe eclipse just did not pick up a file or other updates.
regards, Mike
First of all, I would like to thank Mike (marksml) for being so helpful and attempting to provide a solution for my problem. Unfortunately, his answer did not work for me!
I began to look at all of my previous projects and noticed that the one I was having trouble with was the odd one out (because it was the only one that didn't work) and the factor that made it the odd one out, I found to be the JRE system library version. The project was using the JavaSE-1.7 library but when I changed it to the JavaSE-1.6 like my other projects were using it miraculously worked and exported flawlessly! I'm still curious as to why this is the case, but at least I have it working now...
With thanks and kind regards, Andy
I wanted to learn Java, as recommended by most of the people I downloaded "Thinking in Java" eBook and Source Code Example Lesson files from mindviewinc.com it's download location is this http://www.mindviewinc.com/TIJ4/CodeInstructions.html
These files don't work with Eclipse IDE for some reasons. So we have to build the files using the Build.xml file included in it's source code (Honestly, I do not have any idea what does "build" means here)
I tried building myself but of no use.. It did started building but after reaching some folder it stopped and gave error to install jboss-osgi-installer-1.0.0.jar .. After downloading it, I had no idea what to do with it, so I double clicked it and it asked me the location to install and I installed it in the default location, which was C:\Users\Username/jboss-osgi-1.0.0 and when I tried C:\Program Files\Java** the installation gave error that "this directory cannot be written, please choose another directory!" but anyway I installed it in the default location and it installed..
and again when I tried to build it, it gave me the same error and asked to Install Jboss....... I'm stuck.. This is happening again and again, wasted many days and didn't even crossed 100 pages of it's pdf because of this reason. It's a good eBook though.
I'm stuck in this from months... Please some one build it and make it like a project which could be easily and send me the project file, it would be really appreciated as I can not the solution to this anywhere on search engines..
Ok here's what I did to succesfully import the sources found in the "accesss" folder of you code samples:
Download the javassist jar as per Bruce's instructions, from here:
http://repo2.maven.org/maven2/javassist/javassist/3.9.0.GA/javassist-3.9.0.GA.jar
You must create an Eclipse project for the sources that are used as dependencies for most of the examples, that's the sources in the "net" folder:
in eclipse make new java project.
select the "net" directory, copy it, then in eclipse select the "src" entry in the project you just made, right click on it and select paste.
after eclipse finishes and auto-builds, it will complain about the missing javaassist jar. Right click on the project ->properties->java build path (on the left)->libraries (on the top)-> add external jars... (on the right), browse and select the javassist jar from where you down load it.
now the "net" project should be ok in eclipse
Now let's create the project for the sources in the "access" folder:
create a new java project in eclipse
Now, because Bruce structured his classes like crap, we'll have to make the proper structure in eclipse for them. This means:
a.create a new package called "access"
go to where your the access folder is on your drive, open it, select ONLY the folders (cookie2, desser, mypackage), copy them, then return to eclipse, right click on the "access" package u just made and click paste
now go back to the access dir on your drive, select ONLY the .java files (all of them, not the dirs), copy them, the back to eclipse, click on the src entry in the access project and click paste.
The access project in elcipse will still complain about missing classes form the "net" resouce. Right click on the project in eclipse->properties->java build path->projects (on the top)-> add(on the right)-> check the net project you created earlier-> click ok twice.
Now it should be ok
I hope you got the idea on how dependencies work in eclipse with this example.
For the other parts of you code samples, create separate java projects, add the classes to the proper package (create the packages if Bruce forgot to), and if you are missing external jars, go to http://search.maven.org search and download the jars. Good luck
"This code is designed to work outside of IDEs. Because packages are not introduced until later chapters, and some of the fancier IDEs like Eclipse require all code to be in packages, if you want to use the code inside those IDEs you will have to make some adjustments" - yep, bruce eckel would say that, cause that's the kind of guy he is. He also said there's ONLY checked exceptions in java, and asked for unchecked exeptions to be added as a bonus.
Now, if your sample code has no package, aka it's in the default package, aka when you look in the .java file, right at the top there's no line saying "package what.ever.bla" then all you have to do is:
-in Eclipse create a new Java se project
- open a windows explorer, go to your .java files, select them and copy them
- then in eclipse, right click the src folder in your project and chose "paste"
The files should be added to a "default" package in your eclipse project, without any error
Here is the simplest steps that I find to create a clean Eclipse project for the TIJ4 source code:
Download the source code zip from: http://www.mindviewinc.com/TIJ4/CodeInstructions.html, and unzip it to a folder, say 'TIJ4-code';
Download the additional libraries as in the previous URL, copy tools.jar from your current JDK's lib directory, and put them into TIJ4-code/lib;
Go into the 'TIJ4-code' folder, and run 'python Eclipse.py' (you need python installed on your system). This script adds the missing "package xxx" line to those source java files which don't yet have them, so as to make Eclipse happy. It also generates the Eclipse project files, which doesn't work well for some reason (beyond my limited knowledge on Eclipse), but they aren't needed here;
Open Eclipse and create a new empty java project, say with name 'TIJ4', choose JRE version 1.5, and "create separate folders for sources and class files";
Copy TIJ4-code/lib directory to your new Eclipse project folder;
Right click on the new project and select "Build Path" >> "Configure Build Path", then go to tab "Libraries", "add jars", then select all the jars under your project's lib folder;
Go to "File >> import", choose "General >> File System", select the unzipped folder 'TIJ4-code' as your "From directory". Check the root 'TIJ4-code' in the left panel of the import window, Click on "filter types" and select the .java, so that unnecessary files of other extensions, like *.class, *.py, *.xml, etc can be ignored during the import;
The zipped folder is no longer needed after the new Eclipse project is built. I hope you find this instruction helpful, and have fun learning TIJ4.
If you want to use this code in IDE rather than Eclipse and so on, for example in Intelij Idea or any other, the best way is to compile necessary classes from the TIJ4 with Ant, but it is not easy for the beginners, although it will be a good practice for you. You should make some changes in build.xml files which exists in every directory of TIJ4. Why?
to change version of Java(now we all use Java version higher than 1.5)
to include javaassist.jar library in the "classpath"
to put all compiled files in 'bin' directory(by default without adjustments TIJ4 build.xml puts .class files in the same directory with .java files. That is not a good deal.
For example you need to import and use within IDE(I use Intelij Idea) the class named net.mindview.util.Print ( see Chapter 3):
download TIJ4 and unzip in any directory you want(for example it would be c:\eckel)
download and install AntApache (you can find detailed instructions how to do it in Google) The result is - type in your console ant -version and you should see the answer. So Ant is working.
download javaassist.jar from http://jboss-javassist.github.io/javassist/ . Unzip to any directory, take out javassist.jar and past it to c:\eckel\net
4.There is build.xml file in c:\eckel\net. Now you should make adjustments. Open it with NotePad++ or other editor.
If you don't have Java 1.5 installed on your PC, so change all 'vesion1.5' to 'vesrion1.8' or other version that you have installed.
after tag description put property name = "classpath" value="./;./javassist.jar"/>
<property name = "src_util" value="./mindview/util"/>
<property name = "src_simple" value="./mindview/simple"/>
<property name = "src_atunit" value="./mindview/atunit"/>
<property name = "destdir" value="bin"/>
Then we make targets that will complile util simple or atunit automatically
Change tag available <available
classname="javassist.bytecode.ClassFile"
classpath="${classpath}"
property="javassist"
/>
Now classpath of available = property named 'classpath'. Classpath is the path where java compiler looks for .class files because some of your .java files want them by having import statement. There won't be error message "You must install the Javassist library " any more
Create targets for compiling util simple and so on See the following link with code
Code with targets
You can modify exists targets not to write all the code.
at the top of build.xml file change default="simple"
open cmd, then cd c:\eckel\net , then ant -simple or just ant (simple will run as default)
Please write if you will have some problems. Possibly i forgot mention about something.
Go to Intellij Idea, press Ctrl+Alt+Shift+S
Press +,
Library or directories
choose your c:\eckel\net\bin
5.now you can use import statement for all classes that exist in net.mindview
6.you can make the same with other dirs.
If you wish to you skip the entire Ant build process, I have converted the project to a Maven project (over JDK8), which you can simply import into your Eclipse workspace.
https://github.com/gauravojha/tij4-maven
Thanks to #Sergey Oliv's example. In addition, I needed to provide uncompiled javaassist package with all java files in the 'net' folder too. The .jar wouldn't work by itself.
I must say, this was a lot of work to get going.
Hey all. I am working on a project for school where we are given the .class file but not the source to include in our code. I am using Eclipse, and I want to include the file in my project so I can instantiate objects from it and use it. The file is TokenizerImpl.class, and I want to use it like this: TokenizerImpl tokenizer = new TokenizerImpl(foo);
I put the file in my project folder, and Eclipse says that "TokenizeImpl cannot be resolved as a type", which I assume means it cannot find the class or source. I tried putting it in the "bin" folder of the project and got the same error. Google search and SO search didn't seem to answer this, so I will give it a shot. How do I do this, oh wise ones?
Edit: Oh dear, I found the problem was something else entirely. These solutions worked fine, but I just forgot to create the Tokenizer interface that TokenizerImpl implements. Doh. Thanks for all your help though, I did learn a lot about eclipse.
You can add a directory containing the class files to the Eclipse project, only if it is inside one of your Eclipse projects, either in a generated directory or in one you have created.
This can be done by adding the class folder to the Java build path of the application. You can set this in the Project properties, by visiting Java Build Path -> Libraries -> Add Class Folder. Keep in mind, that you will have to specify the root folder containing the class files in their packages.
Therefore, if you wish to have the compiler access com.stackoverflow.Example.class present in the classes directory under project A (but not in the build path of project A), then you should add 'classes' as a class folder, and not classes/com/stackoverflow as a class folder.
Project -> Properties -> Java Build Path -> Libraries -> Add External Class Folder
The folder must contain a package hierarchy, i.e. if your class is really foo.bar.TokenizerImpl it must be in the subdirectory foo/bar.
You could also JAR the class files that you want to add and add the JAR file to the build dependencies. To me this is the cleanest solution. Internally the JAR file has to have the correct directory structure, of course.
Right click into your project and select Java Build Path to add new dependencies.
Copying it into the bin folder won't work very well because it is meant to hold the result of compiled sources. As soon as you clean anything the file will be gone.
or put everything into a jar file and add this as an external jar.
Other people have now given better answers. This "answer" was mainly to get information from the OP because the original question didn't really tell us, fully, what had been tried. There are now two answers that truly answer the question in a long-term way.
My original answer is left below for context.
Did you copy it to the bin folder within Eclipse or outside Eclipse? If you did this outside Eclipse then you have to right click on the "bin" folder and select "refresh" for Eclipse to see the new file.
A *.class file in the appropriate folder (depending on its package) under the bin directory should do it.
zip the class folder.
Highlight project name, click "Project" in the top toolbar, click "Properties", click "Libraries" tab, click "Add External jars", add the zipped file