JAVA COMPILER API - Cannot finding external class file

Question

I have a simple code to make Java code compiler

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import javax.tools.*;
import java.io.*;
import java.util.*;

public class Compiler extends JFrame
{
    String loc="D:\\java";
    File file=null,
         dir=null;
    boolean success;
    public Compiler()
    {
        super("Highlight example");
        try 
        {
            UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
        } 
        catch (Exception evt) {}
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new GridLayout(1,2));

        JTextPane textPane = new JTextPane();
        JTextArea debug=new JTextArea();
        JButton comp=new JButton("Compile"),
                browse=new JButton("...");

        JTextArea location=new JTextArea();

        JPanel right=new JPanel(),
               up=new JPanel();

        up.setLayout(new BorderLayout());
        up.add(new JScrollPane(location),"Center");
        up.add(browse,"East");

        right.setLayout(new BorderLayout(2,1));
        right.add(up,BorderLayout.NORTH);
        right.add(new JScrollPane(textPane), "Center");
        right.add(comp,"South");
        add(right);
        add(new JScrollPane(debug));
        setSize(800, 400);
        setVisible(true);

        browse.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                success=false;
                UIManager.put("FileChooser.readOnly", Boolean.TRUE);
                JFileChooser fc = new JFileChooser(loc);
                int status = fc.showOpenDialog(new JFrame());
                if (status==JFileChooser.APPROVE_OPTION)
                {
                    debug.setText("");
                    file = fc.getSelectedFile();
                    dir = fc.getCurrentDirectory();
                    try
                    {
                        textPane.read(new FileReader(file), null);
                    }
                    catch(Exception ex)
                    {

                    }
                }
            }
        });

        comp.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                try
                    {   
                        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
                        DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<JavaFileObject>();
                        StandardJavaFileManager fileManager = compiler.getStandardFileManager(diagnostics, null, null);
                        Iterable<? extends JavaFileObject> compilationUnits = fileManager.getJavaFileObjectsFromStrings(Arrays.asList(file+""));
                        String[] option=new String[]{"-g","-parameters"};
                        Iterable<String> options = Arrays.asList(option);
                        JavaCompiler.CompilationTask task=null;

                        fileManager.setLocation(javax.tools.StandardLocation.CLASS_OUTPUT, Arrays.asList(dir));

                        task = compiler.getTask(null, fileManager, diagnostics, options, null, compilationUnits);
                        success = task.call();

                        fileManager.close();
                 //     System.out.println("Success: " + success);
                        if(success==true)
                        {
                            debug.setText("Success");
                        }
                        else
                        {
                            int i=1;
                            for (Diagnostic diagnostic : diagnostics.getDiagnostics())
                                if(diagnostic.getLineNumber()!=-1)
                                    debug.append("Error on line "+diagnostic.getLineNumber()+" in "+ diagnostic+"\n");
                        }
                    }
                    catch(Exception ex)
                    {

                    }
            }
        });
    }

    public static void main(String[]args)
    {
        new Compiler();
    }
}

I don't know why compiler can not find previous result of code before. And I have no idea how to fix that.

For more details, I made an example :

select A.java
Content of A.java
then I have select B.java. look A.java has been compiled with create A.class
B.java can not compile because it can not find class A

And also can not find class inside package folder.

Here is example 2:

A.java has been compiled with create folder <path>\a\b

and access class using import

I have some try

from :

fileManager.setLocation(javax.tools.StandardLocation.CLASS_OUTPUT, Arrays.asList(dir));

to :

fileManager.setLocation(javax.tools.StandardLocation.CLASS_PATH, Arrays.asList(dir));

but it's not working

It's a bit hard to tell from your pictures where those files live. Do they both live in this example folder or do they live in some folder structure a/b? — Makoto
– Makoto, Commented Jul 17, 2016 at 23:17
@Makoto java file inside example folder, class file inside structure a/b folder if they are contains package. — newbie
– newbie, Commented Jul 17, 2016 at 23:30

Sergey Kalinichenko · Accepted Answer · 2016-07-17 10:14:16Z

1

In addition to setting javax.tools.StandardLocation.CLASS_OUTPUT, you need to set javax.tools.StandardLocation.CLASS_PATH to include the same location where you put the previous output:

fileManager.setLocation(javax.tools.StandardLocation.CLASS_OUTPUT, Arrays.asList(dir));
// Set dirClassPath to include dir, and optionally other locations
fileManager.setLocation(javax.tools.StandardLocation.CLASS_PATH, Arrays.asList(dirClassPath));

answered Jul 17, 2016 at 10:14

Sergey Kalinichenko

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4 Comments

newbie Over a year ago

i think it doesn't work if A.java using package, and B using import, post updated.

Sergey Kalinichenko Over a year ago

@newbie You are not importing it correctly. It should be import a.b.*;

Sergey Kalinichenko Over a year ago

@newbie It does not look like the compiler sees that change (the error message still shows no asterisk after b).

Sergey Kalinichenko Over a year ago

@newbie That's odd. I assume that a/b/ directory contains A.class, right?

Lee · Accepted Answer · 2016-07-25 15:55:16Z

1

You need to specify the sourcepath directory, your code

String[] option=new String[]{"-g","-parameters"};,

try this

String[] option=new String[]{"-g","-sourcepath", loc};

where loc is the root directory for the B class. With A properly stored inside its own package.

I've tried your code, with my modification http://kurungkurawal.com/gifs/tut-compile.gif

answered Jul 25, 2016 at 15:55

Lee

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Comments

Bhadresh Bajariya · Accepted Answer · 2018-01-02 10:16:40Z

0

Create jar File of external classes and attach with compiler.

List<String> optionList = new ArrayList<String>();
        // set compiler's classpath to be same as the runtime's
optionList.addAll(Arrays.asList("-classpath", System.getProperty("java.class.path")
                + getValueFromPropertieFile("jarfile1;jarfile2")));

JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, diagnostics, optionList, null,
                compilationUnit);

answered Jan 2, 2018 at 10:16

Bhadresh Bajariya

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