Preventing System.exit() from API

Question

I am using a third party library that does a System.exit() if it encounters exceptions. I am using the APIs from a jar. Is there anyway that I can prevent the System.exit() call because it causes my application to shutdown? I cannot decompile and recompile the jar after removing the System.exit() because of a lot of other licensing issues. I once came across an answer [to some other question that I do not remember] in stackoverflow that we can use the SecurityManager in Java to do something like this.

Answer 1

See my reply to How to avoid JFrame EXIT_ON_CLOSE operation to exit the entire application?.

Edit 1: The source that was linked. Demonstrates how to use a SecurityManager to prevent System.exit(n).

import java.awt.*; import java.awt.event.*; import java.security.Permission;  /** NoExit demonstrates how to prevent 'child' applications from ending the VM with a call to System.exit(0). @author Andrew Thompson */ public class NoExit extends Frame implements ActionListener {    Button frameLaunch = new Button("Frame"),      exitLaunch = new Button("Exit");    /** Stores a reference to the original security manager. */   ExitManager sm;    public NoExit() {      super("Launcher Application");       sm = new ExitManager( System.getSecurityManager() );      System.setSecurityManager(sm);       setLayout(new GridLayout(0,1));       frameLaunch.addActionListener(this);      exitLaunch.addActionListener(this);       add( frameLaunch );      add( exitLaunch );       pack();      setSize( getPreferredSize() );   }    public void actionPerformed(ActionEvent ae) {      if ( ae.getSource()==frameLaunch ) {         TargetFrame tf = new TargetFrame();      } else {         // change back to the standard SM that allows exit.         System.setSecurityManager(            sm.getOriginalSecurityManager() );         // exit the VM when *we* want         System.exit(0);      }   }    public static void main(String[] args) {      NoExit ne = new NoExit();      ne.setVisible(true);   } }  /** This example frame attempts to System.exit(0) on closing, we must prevent it from doing so. */ class TargetFrame extends Frame {   static int x=0, y=0;    TargetFrame() {      super("Close Me!");      add(new Label("Hi!"));       addWindowListener( new WindowAdapter() {         public void windowClosing(WindowEvent we) {            System.out.println("Bye!");            System.exit(0);         }      });       pack();      setSize( getPreferredSize() );      setLocation(++x*10,++y*10);      setVisible(true);   } }  /** Our custom ExitManager does not allow the VM to exit, but does allow itself to be replaced by the original security manager. @author Andrew Thompson */ class ExitManager extends SecurityManager {    SecurityManager original;    ExitManager(SecurityManager original) {      this.original = original;   }    /** Deny permission to exit the VM. */    public void checkExit(int status) {      throw( new SecurityException() );   }    /** Allow this security manager to be replaced,   if fact, allow pretty much everything. */   public void checkPermission(Permission perm) {   }    public SecurityManager getOriginalSecurityManager() {      return original;   } } 

Answer 2

There is a blog post here,

http://jroller.com/ethdsy/entry/disabling_system_exit

Basically it installs a security manager which disables System.exit() with code from here,

  private static class ExitTrappedException extends SecurityException { }    private static void forbidSystemExitCall() {     final SecurityManager securityManager = new SecurityManager() {       public void checkPermission( Permission permission ) {         if( "exitVM".equals( permission.getName() ) ) {           throw new ExitTrappedException() ;         }       }     } ;     System.setSecurityManager( securityManager ) ;   }    private static void enableSystemExitCall() {     System.setSecurityManager( null ) ;   } 

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Edit: Max points out in comments below that

as of Java 6, the permission name is actually "exitVM."+status, e.g. "exitVM.0".

However, the permission exitVM.* refers to all exit statuses, and exitVM is retained as a shorthand for exitVM.*, so the above code still works (see the documentation for RuntimePermission).