Jython, unresolved import - java class

Question

I'm trying out jython, and got stuck pretty early with the example from chapter 10 http://www.jython.org/jythonbook/en/1.0/JythonAndJavaIntegration.html the math import does work from the java library. But I cannot get the custom class Beach to work.

I saw an identical post Jython won't import user-defined class; ImportError: No module named ****** However I did not understand the accepted answers approach.

So I'm hoping for a bit clarification.

Below is my project structure.

import Beach

b = Beach("Cocoa Beach","Cocoa Beach")
print (b.getName(Beach.getName()))

import Beach: Unresolved import: Beach

EDIT: Got it working with the following:

import sys
sys.path.append('C:\Users\Rasmus\Desktop')

import Beach

beach = Beach("Cocoa Beach","Cocoa Beach")
beach.getName()
print(beach.getName())

However pydev eclipse still marks import Beach as an unresolved import.

The Beach class

public class Beach {

    private String name;
    private String city;


    public Beach(String name, String city){
        this.name = name;
        this.city = city;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

}

I don't see the class file in your directories. Did you run "javac src/Beach.java"? Only after doing that will you get a class file. It is a good practice to keep files of each language in a separate directory. Move your .java files to a Java directory and create a Java project for the same. Put your python files in a separate directory. — randominstanceOfLivingThing, Apr 15 '16 at 19:56
I made two seperate directories. Are there any way to make python create the java.class file by itself, so that I made easily edit my java classes. — PushALU, Apr 15 '16 at 20:30

randominstanceOfLivingThing · Accepted Answer · 2016-04-15T20:38:12.167

2

You need to have the compiled class in Jython class path. You can only import compiled class files.

As metioned in the link that you had in your question:

As we had learned in Chapter 8, one thing you’ll need to do is ensure that the Java class you wish to use resides within your CLASSPATH. In the example above, I created a JAR file that contained the Beach class and then put that JAR on the CLASSPATH.

The compilation is done by using javac command which is part of JDK. Creating a jar file is done with the command jar command part of JDK.

It is not a good practice to have files of different files in the same directory. You should create a Java project for your .java file and the Jython files in a separate directory.

Look at using-a-jar-or-java-project-in-your-jython-app.

edited Apr 15 '16 at 20:38

answered Apr 15 '16 at 15:00

randominstanceOfLivingThing

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Which I have no idea about how to proceed with. – PushALU Apr 15 '16 at 15:07
I tried exporting my class Beach as a jar file, and pasted it into the src folder of the jyt project. But that did not do it. Isn't src the classpath? – PushALU Apr 15 '16 at 15:28
Java source file need to be compiled using Javac and then you will get a .class file. – randominstanceOfLivingThing Apr 15 '16 at 15:29
I did get it to work now. But it still complains and says it's unresolved import? – PushALU Apr 15 '16 at 15:41
Did you add to classpath following directions at https://wiki.python.org/jython/LearningJython#classpath-and-python-path – randominstanceOfLivingThing Apr 15 '16 at 15:50
I tired adding it with the append, but still shows there's an error. Are there any way for jython to do these steps automatically? – PushALU Apr 15 '16 at 16:05
Can you edit your question and show the class that you created and the jar file. Show the classpath changes. – randominstanceOfLivingThing Apr 15 '16 at 18:20

Jython, unresolved import - java class

1 Answers1