CODEWITHSUNDEEP
javafilenotfoundexceptionprocessbuilder
LifeOnNet
LifeOnNet

Reputation: 107

How can I detect if file not found for execution by ProcessBuilder in Java?

I have this part of code, supposed to start msg.exe subprocess on Windows:

    ProcessBuilder pb = new ProcessBuilder("msg.exe");
    try {
        proc = pb.start();
    } catch (IOException  ex) {
        jLabel4.setText("Cannot launch message box process");
        return;
    }

Now I tried to delete/rename msg.exe and no exception thrown: both lines in catch clause aren't executed. How can I detect if file not found for execution by process builder?

If I try to catch FileNotFoundException, it says this one is already caught (probably as a part of IOException). If I try to catch only FileNotFoundException, it requires to catch IOException with warning.

Upvotes: 1

Views: 860

Answers (3)

xehpuk
xehpuk

Reputation: 8250

My shot in the dark:

You have an executable named "msg.exe" in the directory of your Java application which you are trying to execute from your Java code. When renaming or deleting the file, you are expecting new ProcessBuilder("msg.exe").start() to throw an IOException.

This will not happen since if there is no file called "msg.exe" in the directory, then it will search for it in your %PATH%, and finally find it in C:\Windows\System32\, which is probably what you did not intend.

This dilemma can be solved by explicitly stating that the file you are trying to execute must exist in the current directory: new ProcessBuilder("./msg.exe")

Upvotes: 1

Neeraj Jain
Neeraj Jain

Reputation: 7720

Your code will not throw FileNotFoundException , it will throw IOException

See the Documentation

Below is the exception I got , As I am on linux so there is no need to change the name of msg.exe to some other to generate exception 

java.io.IOException: Cannot run program "msg.exe": error=2, No such file or directory
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
    at Neeraj.main(Neeraj.java:8)
Caused by: java.io.IOException: error=2, No such file or directory
    at java.lang.UNIXProcess.forkAndExec(Native Method)
    at java.lang.UNIXProcess.<init>(UNIXProcess.java:187)
    at java.lang.ProcessImpl.start(ProcessImpl.java:134)
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:1029)
    ... 1 more

Upvotes: 0

MG_7
MG_7

Reputation: 61

The start() method can be invoked repeatedly from the same instance to create new subprocesses with identical or related attributes.Each process builder manages these process attributes

public static void main(String[] args) {     
       ProcessBuilder pb = new ProcessBuilder("msg.exe");
     //  pb.directory(new File("c:\\xyzwsdemo"));
        try {
             Process   proc = pb.start();
        } catch (IOException  ex) {
            System.out.println("Cannot launch message box process");
            return;
        }
}

executed the above class : No error

public static void main(String[] args) {


       ProcessBuilder pb = new ProcessBuilder("msfg.exe");
     //  pb.directory(new File("c:\\xyzwsdemo"));
        try {
             Process   proc = pb.start();
        } catch (IOException  ex) {
            System.out.println("Cannot launch message box process");
            return;
        }
}

Rename msg.exe to msfg.exe -Exception caught, same after deleting the code

Did you try executing in main class and check again?

Upvotes: 0

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