Created a utility for invoking tasks such that they can be retried by the

user if they fail (presumably after making some external change like
changing file permissions or restarting a database).


git-svn-id: https://samskivert.googlecode.com/svn/trunk@104 6335cc39-0255-0410-8fd6-9bcaacd3b74c

projects/samskivert/src/java/com/samskivert/swing/util/RetryableTask.java

@@ -0,0 +1,52 @@
+//
+// $Id: RetryableTask.java,v 1.1 2001/03/19 23:03:56 mdb Exp $
+
+package com.samskivert.swing.util;
+
+import java.awt.Component;
+import javax.swing.*;
+import com.samskivert.Log;
+
+/**
+ * A retryable task is one that is allowed to fail at which point a dialog
+ * is presented to the user asking them if they would like to retry the
+ * task. In general, such practices are discouraged because the software
+ * should handle retrying itself, but in cases where failure results in
+ * the abandonment of a lot of work and automatic retries have already
+ * been tried, it can be reasonable to give the user one last chance to
+ * remedy any problems that are causing the error.
+ */
+public abstract class RetryableTask
+{
+    /**
+     * This should be implemented by the retryable task user to perform
+     * whatever they wish to be done in a retryable manner.
+     */
+    public abstract void invoke () throws Exception;
+
+    /**
+     * Invokes the supplied task and catches any thrown exceptions. In the
+     * event of an exception, the provided message is displayed to the
+     * user and the are allowed to retry the task or allow it to fail.
+     */
+    public void invokeTask (Component parent, String retryMessage)
+        throws Exception
+    {
+        while (true) {
+            try {
+                invoke();
+
+            } catch (Exception e) {
+                Object[] options = new Object[] {
+                    "Retry operation", "Abort operation" };
+                int rv = JOptionPane.showOptionDialog(
+                    parent, retryMessage + "\n\n" + e.getMessage(),
+                    "Operation failure", JOptionPane.YES_NO_OPTION,
+                    JOptionPane.WARNING_MESSAGE, null, options, options[1]);
+                if (rv == 1) {
+                    throw e;
+                }
+            }
+        }
+    }
+}