Compiling another java code from our code

[madhav.dubey9]

I need to compile a java code and print the output to a text file .
If the file gets compiled successfully then run that class file.

I have tried using Process class but does not work..Any other solution???

[jim829]

I haven't see the first solution.

Regards,
Jim

[madhav.dubey9]

here is the code i tried

import java.util.*;
import java.io.*;
public class BadExecJavac
{
public static void main(String args[])
{ try
{
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("cmd/c javac "+path address of file to be compiled);

}
catch (Throwable t) { t.printStackTrace(); }
}
}

[DarrylBurke]

Guide For New Members
BB Code List - Java Programming Forum - Learn Java Programming

db

[jim829]

I didn't try to compile anything but this worked as expected. Looks like it could be a path environment issue. Make certain you use complete pathnames.

public class BadExecJavac {
   public static void main(String args[]) {
      try {
         Runtime rt = Runtime.getRuntime();
         Process proc = rt.exec("C:/WINDOWS/system32/cmd.exe /c dir > \"C:/Documents and Settings/user/Desktop/dir.txt\"");

      }
      catch (Throwable t) {
         t.printStackTrace();
      }
   }
}

Regards,
Jim

[DarrylBurke]

... and When Runtime.exec() won't

db

[madhav.dubey9]

dir command works completely fine but javac dont..why??

[jim829]

I don't know but I am interested enough to keep trying. And normally I don't ask why someone wants to do something but in this case I am curious as there are much better ways to control compilation of source code.

Regards,
Jim

[Tolls]

What does "does not work" mean?
You're not doing anything with the either the error stream or the standard output stream, so you're not going to see any errors coming out of the execution.

[SurfMan]

Here's code to compile it using the JavaCompiler API. It's *very* quick and dirty, but it does the job. I am not sure how to run it using pure Java code.

package bla;

import javax.tools.JavaCompiler;
import javax.tools.ToolProvider;
import java.io.ByteArrayOutputStream;

public class Compile {

    public static void main(String[] args) {
        String fileToCompile = "/home/username/MyFile.java";
        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

        ByteArrayOutputStream os = new ByteArrayOutputStream();

        int compilationResult = compiler.run(null, null, os, fileToCompile);
        if (compilationResult == 0) {
            System.out.println("Compilation is successful");
        }
        else {
            System.out.println("Compilation Failed");
            System.out.println(new String(os.toByteArray()));
        }
    }

}

[madhav.dubey9]

thanx now i m trying to run the compiled file..

[madhav.dubey9]

should i make that file a batch file....so that my code can call it??any suggestions?

[jim829]

What?!? Are you suggesting that you want your code to call SurfMan's code to compile a program?

Why don't you just use ANT?

Regards,
Jim

[SnakeDoc]

Ant might be overkill for a small project or if he's just learning... although it is the accepted method to compile code automagically...

maybe try a constuctor to initialize the Compile class with the path to your java source you want compiled. Then in your code, you can just call:

so modify the sample to:

package bla;
 
import javax.tools.JavaCompiler;
import javax.tools.ToolProvider;
import java.io.ByteArrayOutputStream;
 
public class Compile {

    private String path;

    public Compile(String path) { // constuctor initializes to set file path
        this.path = path;
    }
    public Compile() {  // empty constructor
    }

    public void setCompilePath(String path) {  // set file path
        this.path = path;
    }
    public String getCompilePath() {  // get file path
        return this.path;
    }
 
    public void doCompile() {  // compile file located at path

        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
 
        ByteArrayOutputStream os = new ByteArrayOutputStream();
 
        int compilationResult = compiler.run(null, null, os, this.path;
        if (compilationResult == 0) {
            System.out.println("Compilation is successful");
        }
        else {
            System.out.println("Compilation Failed");
            System.out.println(new String(os.toByteArray()));
        }
    }
 
}

and call it from your code by doing:

Compile compile = new Compile("/path/to/your/source/file.java");
compile.doCompile()

might be a "saner" approach than trying to integrate batch files to call other files to call other files, etc...

[madhav.dubey9]

i still cannot run my compiled file...please help..... :(

[SurfMan]

What code do you use to run the class file?

[Tolls]

Have you tried to actually compile that file "by hand" (ie from the command line)?
In other words, does it actually compile?

If so, then what happens when you try to run it.

"It does not work" is no use to us in resolving your problem. We cannot see your computer from here.

[SnakeDoc]

if you really insist on going this route to run other java programs... read up on Runtime.getRuntime().exec() :

Runtime (Java 2 Platform SE v1.4.2)

[DarrylBurke]

... or load the class using a ClassLoader and invoke the main(...) method using reflection. If you have enough knowledge and experience to go down that path, my File Class Loader may be useful.

db