Question

I created a backup program. Program is running great but the logs are not generating. I am generating logs using three methods ,

System.out.println(message);

        try {

            if(logFileWriter != null){

                logFileWriter.write(message);
                logFileWriter.newLine();
                logFileWriter.flush();
            }

            Runtime.getRuntime().exec("echo " + message);

        } catch (IOException e1) {}

Log file initializer:

private static void initLog() { 
    File logFileObj = new File(logFile); 
    try { 
        FileWriter fileWriter = new FileWriter(logFileObj); 
        logFileWriter = new BufferedWriter(fileWriter); 
    } catch (IOException e) { 
        e.printStackTrace(); 
    } 
}

Here message is the message that I want to log. The file writer is initiated by the log file path given by the user at the run time using the command line argument.

When i am trying to run the program using the eclipse, logs are creating but when i run the executable jar file, no logs are creating. What can be the reason.

Answer 1

Assumption: You are on Windows and you are creating this executable jar from Eclipse.

Not sure how your complete code looks like this is what I did based on your code:

package com.mumz.test.executable.jar;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

public class JustPrint {    
    private static String         logFile   = "backooopLog.txt";
    private static BufferedWriter   logFileWriter;
    private static void initLog() {
            File logFileObj = new File(logFile);
        try {
            FileWriter fileWriter = new FileWriter(logFileObj);
            logFileWriter = new BufferedWriter(fileWriter);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        initLog();
        String message = "hello word";
        System.out.println(message);
        try {
            if (logFileWriter != null) {
                logFileWriter.write(message);
                logFileWriter.flush();
            }
            Runtime.getRuntime().exec("echo " + message);
        } catch (IOException e1) {
            e1.printStackTrace();
        } finally{
            try {
                logFileWriter.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}    

Then project->right click->export->Runnable Jar -> Select JustPrint in the launch configuration and give the file location – > Finish

Then open command prompt browse where jar file was created, then type this command

java -jar exectest.jar 

(Considering Java path is set and I gave my jar name as exectest.jar, I can see log file being created in the same directory where jar file is located also, on my command prompt I can stacktrace while creating process.

Now with this can you trace your code and see if you do something like this or different, post your findings.