带日志文件但不能用java程序执行的bat文件不生成

Question

I created one bat file in that I am trying to copy folder and generate its log into myLog.txt file Now I am trying to run the bat file through the java program it's getting executed but it's not able to generate a log file please help me

public static void allBatch()
    {
        
         try {
                // Process p =  Runtime.getRuntime().exec("cmd /c stopTomact.bat", null, new File("C:\\Users\\Ajay\\Documents"));
                 Process process =Runtime.getRuntime().exec("cmd /C start C:\\Users\\Ajay\\Documents\\batchFile.bat");
                   System.out.println("Stopped"); 
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
        
        
    }

@echo off

@echo off

call :main >myLog.txt 2>&1

:main if exist "C:\\Users\\Ajay\\Documents\\old Tomcat\\Controller*.*" (

xcopy /e "C:\\Users\\Ajay\\Documents\\old Tomcat\\Controller*.*" "C:\\Users\\Ajay\\Documents\\newTomcat\\Controller*" /y echo %date%-----Copy Successful------%time%

echo --------------------------------------------------- net stop Tomcat8 sc query Tomcat8 echo %date%-----Stop Successful------%time%

rem start notepad "C:\\Users\\Ajay\\Documents"

)else echo %date%------- sorry Failed TO Copy -----%time%

timeout 5 > nul exit

Answer 1

You invoke the Runtime.exec() method. The method returns a Process instance, and in it's documentation you can read

By default, the created process does not have its own terminal or console. All its standard I/O (ie stdin, stdout, stderr) operations will be redirected to the parent process, where they can be accessed via the streams obtained using the methods getOutputStream(), getInputStream(), and getErrorStream(). The parent process uses these streams to feed input to and get output from the process. Because some native platforms only provide limited buffer size for standard input and output streams, failure to promptly write the input stream or read the output stream of the process may cause the process to block, or even deadlock. https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Process.html

So it is likely your process is started by the OS but gets blocked due to I/O restrictions. Get around that by reading the STDOUT and STDERR streams until your process finishes. One good programming model is visible at https://www.baeldung.com/run-shell-command-in-java