The .classpath file reflects the content of all the settings that you apply manually to your BUILD PATH setup within your project.

In other words: while using the eclipse UI to setup the BUILD PATH, all that information goes into the .classpath file.

And it is perfectly possible to stop eclipse and make changes to that file within your preferred editor; then restart eclipse, probably do a full refresh; and (unless you messed up) the changes should be visible when opening your BUILD PATH settings again.

Answer from GhostCat on Stack Overflow
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Eclipse
archive.eclipse.org › eclipse › downloads › documentation › 2.0 › html › plugins › org.eclipse.jdt.doc.user › tasks › tasks-114.htm
Adding a classpath variable to the build path
Select the project to which you want to add the classpath variable ... In the Properties page, select the Java Build Path page. On the Libraries tab, click Add Variable for adding a variable that refers to a JAR file. The New Variable Classpath Entry dialog appears which shows all available ...
Discussions

How to place a file on classpath in Eclipse? - Stack Overflow
As this documentation says, "For example if you place this jndi.properties file on your classpath", but how can I place the .properties file on my classpath if I am using Eclipse? More on stackoverflow.com
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java - What's in an Eclipse .classpath/.project file? - Stack Overflow
We recently had an issue with an Eclipse project for one of our team members. Tomcat was not deploying JARs of the application. We eventually noticed the .classpath Eclipse file was not the same ... More on stackoverflow.com
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java - Missing .classpath file in Eclipse project - Stack Overflow
I have recently returned to a project after not using it for a couple of weeks. The project was not created in Eclipse it was imported, and there is no '.classpath' file in the project workspace. ... More on stackoverflow.com
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Adding a library to .classpath file in Eclipse
The build works fine from the command line (it adds the directory containing the generated class files to the classpath) and everything builds and executes. When doing a Gradle/Refresh Gradle Project in Eclipse, it regenerates the .classpath file without including that directory as a lib. I ... More on discuss.gradle.org
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October 24, 2019
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Reddit
reddit.com › r/javahelp › trying to understand classpath file
r/javahelp on Reddit: Trying to understand classpath file
March 29, 2024 -

I just started learning Java so we have a study group where we are supposed to create a simple desktop application using Eclipse IDE and WindowBuilder.

I created the base project and then proceeded to push it to the shared repository. The rest of the people in the team tried executing the base project without success, while I could run it without any issues.

After a while, one of the members realized there is a problem with the classpatch file:

<?xml version="1.0" encoding="UTF-8"?>

<classpath> <classpathentry kind="src" path="src"/> <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE\_CONTAINER"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/com.ibm.icu\_74.2.0.jar" sourcepath="/snap/eclipse/85/plugins/com.ibm.icu\_74.2.0.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/jakarta.annotation-api\_2.1.1.jar" sourcepath="/snap/eclipse/85/plugins/jakarta.annotation-api\_2.1.1.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.core.commands\_3.12.0.v20240214-1640.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.core.commands\_3.12.0.v20240214-1640.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.core.runtime\_3.31.0.v20240215-1631.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.core.runtime\_3.31.0.v20240215-1631.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.e4.ui.di\_1.5.300.v20240116-1723.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.e4.ui.di\_1.5.300.v20240116-1723.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.equinox.common\_3.19.0.v20240214-0846.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.equinox.common\_3.19.0.v20240214-0846.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.equinox.registry\_3.12.0.v20240213-1057.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.equinox.registry\_3.12.0.v20240213-1057.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.jface\_3.33.0.v20240214-1640.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.jface\_3.33.0.v20240214-1640.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.jface.text\_3.25.0.v20240207-1054.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.jface.text\_3.25.0.v20240207-1054.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.osgi\_3.19.0.v20240213-1246.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.osgi\_3.19.0.v20240213-1246.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.swt.gtk.linux.x86\_64\_3.125.0.v20240227-1638.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.swt.gtk.linux.x86\_64\_3.125.0.v20240227-1638.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.text\_3.14.0.v20240207-1054.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.text\_3.14.0.v20240207-1054.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.ui.forms\_3.13.200.v20240108-1539.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.ui.forms\_3.13.200.v20240108-1539.jar"/> <classpathentry kind="lib" path="/snap/eclipse/85/plugins/org.eclipse.ui.workbench\_3.131.100.v20240221-2107.jar" sourcepath="/snap/eclipse/85/plugins/org.eclipse.ui.workbench\_3.131.100.v20240221-2107.jar"/> <classpathentry kind="output" path="bin"/> </classpath>

This is making reference to several libs which exist only in my notebok, where I am using Ubuntu. They are trying to run it in Windows.

Is it not kind of stupid to refer to these libs this way? I am still trying to understanc why Java would make reference to these libs assuming all of us would be using Ubuntu? Nobody else in my team has the snap folder :/

Could you please help me understand what is going on? How can we fix it?

I tried looking for some videos explaining the classpath file but no luck so far.

Thank you :(

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The Eclipse .classpath and .project files as you have found out have absolute file system refs pointing to dependent jars, plugins and other resources that only work on your machine, unless all your team mates have PCs set up with identical filesystem layouts and files in expected locations … highly unlikely. For this reason .classpath, .project, .settings are usually ignored from your git commits and not shared with others. As an alternative, use a Maven pom.xml file to describe your 3rd party dependencies. Each other dev can import the project as a Maven project into Eclipse and it will download deps and set your classpath. Gradle is another alternative.
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Eclipse is a runtime environment for plugins. Virtually everything you see in Eclipse is the result of plugins installed on Eclipse, rather than Eclipse itself.

The .project file is maintained by the core Eclipse platform, and its goal is to describe the project from a generic, plugin-independent Eclipse view. What's the project's name? what other projects in the workspace does it refer to? What are the builders that are used in order to build the project? (remember, the concept of "build" doesn't pertain specifically to Java projects, but also to other types of projects)

The .classpath file is maintained by Eclipse's JDT feature (feature = set of plugins). JDT holds multiple such "meta" files in the project (see the .settings directory inside the project); the .classpath file is just one of them. Specifically, the .classpath file contains information that the JDT feature needs in order to properly compile the project: the project's source folders (that is, what to compile); the output folders (where to compile to); and classpath entries (such as other projects in the workspace, arbitrary JAR files on the file system, and so forth).

Blindly copying such files from one machine to another may be risky. For example, if arbitrary JAR files are placed on the classpath (that is, JAR files that are located outside the workspace and are referred-to by absolute path naming), the .classpath file is rendered non-portable and must be modified in order to be portable. There are certain best practices that can be followed to guarantee .classpath file portability.

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Complete reference is not available for the mentioned files, as they are extensible by various plug-ins.

Basically, .project files store project-settings, such as builder and project nature settings, while .classpath files define the classpath to use during running. The classpath files contains src and target entries that correspond with folders in the project; the con entries are used to describe some kind of "virtual" entries, such as the JVM libs or in case of eclipse plug-ins dependencies (normal Java project dependencies are displayed differently, using a special src entry).

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Coderanch
coderanch.com › t › 105229 › ide › set-ClassPath-eclipse
How to set ClassPath in eclipse (IDEs and Version Control forum at Coderanch)
... Setting application specific class path in Eclipse is easier and you can do that by following below steps. Right Click on Project --> Properties --> Java Build Path --> (Here You can use either "Add JARs" or "Add External JARs") depending upon the physical location of your JAR files in ...
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Eclipse
help.eclipse.org › latest › topic › org.eclipse.jdt.doc.isv › guide › jdt_api_classpath.htm
Setting the Java build path
A source folder may be assigned its own output location which determines where generated class files should be placed. If none is specified, then class files will be placed in the containing project's output location (see IJavaProject.setOutputLocation). The following is an example classpath entry that denotes the source folder 'src' of project 'MyProject':
Find elsewhere
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Mercer
theochem.mercer.edu › csc204 › ClassPaths.pdf pdf
Adding Class Files to your Eclipse Build Path
thing you need to do is add a “Class Files” folder to the “Project 1” directory.
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Techwalla
techwalla.com › tech support › how to
How to Set the Classpath in Eclipse | Techwalla
February 9, 2017 - Right click on the name of the project that you want to build a classpath for in the Package Explorer bar. Click "Build Path" and then choose "Configure Build Path...". ... Click "Add Folder..." to add the source that you want to build the path ...
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The Eclipse Foundation
eclipse.org › forums › index.php › t › 106851
Eclipse Community Forums: Eclipse Platform » How to view .classpath file | The Eclipse Foundation
March 27, 2008 - The Eclipse Foundation - home to a global community, the Eclipse IDE, Jakarta EE and over 350 open source projects, including runtimes, tools and frameworks.
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Coderanch
coderanch.com › t › 105832 › ide › finding-classpath-eclipse
finding classpath from eclipse (IDEs and Version Control forum at Coderanch)
Your Eclipse project's root directory should hold an XML file called ".classpath" that defines the class path. Author of Test Driven (2007) and Effective Unit Testing (2013) [Blog] [HowToAskQuestionsOnJavaRanch] ... On the other hand if you just want to run one of your own classes in the console, and you developed it in an Eclipse project, then everything that is in that project's build path should be in your classpath when you run the class at the command line.
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CodingTechRoom
codingtechroom.com › question › -eclipse-classpath-file
.classpath File in Eclipse: What It Is and How to Use It - CodingTechRoom
The .classpath file is a crucial configuration file in Eclipse IDE that defines the classpath for your Java projects. It specifies module paths and libraries needed for compiling and running Java applications.
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Blogger
ironcladzone.blogspot.com › 2014 › 03 › show-hidden-classpath-project-files-in.html
Iron Clad Zone: Show hidden .classpath .project files in Eclipse
In order to do so, click the small triangle on the right top side of Project Explorer and select Customize View. Just deselect / un-tick the .* resources option and refresh your project.
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TutorialsPoint
tutorialspoint.com › What-are-classpath-of-projects-in-Java-eclipse-projects
What are classpath of projects in Java eclipse projects?
February 20, 2020 - You can include Jar files to which you need to set the classpath in the eclipse project using build path Step 1 − Right click on the project Select Build Path → Configure Build Path.
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Gradle
docs.gradle.org › current › dsl › org.gradle.plugins.ide.eclipse.model.EclipseClasspath.html
EclipseClasspath - Gradle DSL Version 9.6.0
Used by the GenerateEclipseClasspath task to generate an Eclipse .classpath file. The following example demonstrates the various configuration options. Keep in mind that all properties have sensible defaults; only configure them explicitly if the defaults don't match your needs.
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Javaperspective
javaperspective.com › how-to-set-the-classpath-in-eclipse.html
JavaPerspective.com - 1.3.8. How to set the classpath in Eclipse
January 25, 2013 - To set the classpath in Eclipse, right-click the project in the package explorer and select Build Path -> Configure Build Path... as shown below: ... Usually, you add external JAR files to the classpath by clicking the button Add External JARs.... External JARs are JAR files that are outside ...
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GitHub
github.com › randoop › randoop › issues › 217
How can I read a .classpath file from Eclipse? · Issue #217 · randoop/randoop
July 14, 2017 - If randoop was able to read this file and build the classpath based on it, rather than me having to declare the dependencies when calling it, especially when the project gets large and I need to manage multiple dependencies. ... java -ea -classpath C:\dev\dev\target\classes;C:\Users\Yeikel.m2\repository\org\aspectj\aspectjrt\1.8.10\aspectjrt-1.8.10.jar;r;C:/Randoop/randoop-all-3.1.5.jar randoop.main.Main gentests --classlist=classes.txt --timelimit=20 ... java -ea -classpath C:\dev\dev.classpath;C:\dev\dev\target\classes;C:/Randoop/randoop-all-3.1.5.jar randoop.main.Main gentests --classlist=classes.txt --timelimit=20
Author   randoop
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Buggybread
javasearch.buggybread.com › InterviewQuestions › questionSearch.php
What is a .classpath file in eclipse ?
Ans. .classpath specifies the source java and resource folders that are used by Builders to build. Help us improve. Please let us know the company, where you were asked this question : ... Have you ever had problem getting your projects in eclipse refreshed after you made changes in the Pom files ?