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Message:

a coding techniqe that will force cleanup (try/finally)

Posted by Chris Bedford on January 06, 2002 at 11:54 PM

Hi...

I just tried this out and it seems to work... this is a technique that i think you can use when u want to provide
a way for users of your class to ensure an object's cleanup
method is invoked no matter what kind of whacky control
flows (e.g., exceptions) happen....

import java.io.*;
import java.util.*;

public class finx {

int tidied = 0;

finx() {
tidied = 0;
System.out.println("made a finx");
}

void yelp() {
System.out.println("arf arf");
}

void cleanup() {
tidied = 1;
System.out.println("cleanedup");
}

// Here i am using finalize as a debugging technique to catch instances
// when programmers have forgotten to call cleanup. On linux i find
// that i need to call System.runFinalizersOnExit(true) to force the
// finalizer to run... runFinalizersOnExit is deprecated, but this
// just a sanity check anyway.

protected void finalize() {
if (tidied == 0) {
System.out.println("exited with out tidy");
} else {
System.out.println("exited WITH TIDY");
}
}

public static void main(String[] args) {
if (args.length < 1) {
System.out.println(
"Usage: java Words ");
System.exit(1);
}
System.runFinalizersOnExit(true);

finx m = new finx();
finx f = new finx();
try {
if (args[0].substring(0, 1).equals("r")) {
System.out.println("returning");
return;
}
if (args[0].substring(0, 1).equals("e")) {
finx g = null;
g.yelp();
}

System.out.println("end of block");

} finally {
f.cleanup();
}

}
}