Java tutorial
/******************************************************************************* * Copyright (c) 2003, 2006 IBM Corporation and others. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package com.maccasoft.ui.internal.application; import java.text.MessageFormat; import org.eclipse.jface.dialogs.IDialogConstants; import org.eclipse.jface.dialogs.MessageDialog; import org.eclipse.jface.window.Window; import org.eclipse.osgi.util.NLS; import org.eclipse.swt.SWT; import org.eclipse.swt.SWTError; import org.eclipse.swt.widgets.MessageBox; import org.eclipse.swt.widgets.Shell; import org.eclipse.ui.application.IWorkbenchConfigurer; /** * Handles exception while running the event loop. * <p> * In case of a "simpler" exception such as NPE, log the exception, * open a dialog to inform the user and try to keep running. * In case of a exception like OutOfMemory and SWTError, log the exception, * open a dialog to ask the user to decide if the workbench should * be terminated. * </p> */ public final class WorkbenchExceptionHandler { private int exceptionCount = 0; private InternalErrorDialog dialog; private Shell defaultParent = new Shell(); private boolean closing = false; private IWorkbenchConfigurer workbenchConfigurer; //Pre-load all Strings trying to run as light as possible in case of fatal errors. private static String MSG_OutOfMemoryError = "An out of memory error has occurred."; private static String MSG_StackOverflowError = "A stack overflow error has occurred."; private static String MSG_VirtualMachineError = "A virtual machine error has occurred."; private static String MSG_SWTError = "An SWT error has occurred."; private static String MSG_FATAL_ERROR = "{0}\nYou are recommended to exit the workbench.\nSubsequent errors may happen and may terminate the workbench without warning.\nSee the .log file for more details.\n\nDo you want to exit the workbench?"; private static String MSG_FATAL_ERROR_Recursive = "An internal error occurred while showing an internal error."; private static String MSG_FATAL_ERROR_RecursiveTitle = "Internal error"; /** * Creates the exception handle for the IDE application * * @param configurer an object for configuring the workbench */ public WorkbenchExceptionHandler(IWorkbenchConfigurer configurer) { workbenchConfigurer = configurer; } /** * Handles an event loop exception * * @param t the exception to handle */ public void handleException(Throwable t) { try { exceptionCount++; if (exceptionCount > 1) { if (closing) { return; } Shell parent = defaultParent; if (dialog != null && dialog.getShell() != null && !dialog.getShell().isDisposed()) { parent = dialog.getShell(); } MessageBox box = new MessageBox(parent, SWT.ICON_ERROR | SWT.YES | SWT.NO | SWT.SYSTEM_MODAL); box.setText(MSG_FATAL_ERROR_RecursiveTitle); box.setMessage(MessageFormat.format(MSG_FATAL_ERROR, new Object[] { MSG_FATAL_ERROR_Recursive })); int result = box.open(); if (result == SWT.YES) { closeWorkbench(); } } else { if (openQuestionDialog(t)) { closeWorkbench(); } } } finally { exceptionCount--; } } /** * Close the workbench and make sure all exceptions are handled. */ private void closeWorkbench() { if (closing) { return; } try { closing = true; if (dialog != null && dialog.getShell() != null && !dialog.getShell().isDisposed()) { dialog.close(); } workbenchConfigurer.emergencyClose(); } catch (RuntimeException re) { // Workbench may be in such bad shape (no OS handles left, out of memory, etc) // that is cannot even close. Just bail out now. System.err.println("Fatal runtime error happened during workbench emergency close."); //$NON-NLS-1$ re.printStackTrace(); throw re; } catch (Error e) { // Workbench may be in such bad shape (no OS handles left, out of memory, etc) // that is cannot even close. Just bail out now. System.err.println("Fatal error happened during workbench emergency close."); //$NON-NLS-1$ e.printStackTrace(); throw e; } } /** * Inform the user about a fatal error. Return true if the user decide to * exit workbench or if another fatal error happens while reporting it. */ private boolean openQuestionDialog(Throwable internalError) { try { String msg = null; if (internalError instanceof OutOfMemoryError) { msg = MSG_OutOfMemoryError; } else if (internalError instanceof StackOverflowError) { msg = MSG_StackOverflowError; } else if (internalError instanceof VirtualMachineError) { msg = MSG_VirtualMachineError; } else if (internalError instanceof SWTError) { msg = MSG_SWTError; } else { if (internalError.getMessage() == null) { msg = "An internal error has occurred.\nSee the .log file for more details.\n\nDo you want to exit the workbench?"; } else { msg = NLS.bind( "An internal error has occurred.\n{0}\nSee the .log file for more details.\n\nDo you want to exit the workbench?", internalError.getMessage()); } return openQuestion(null, "Internal error", msg, internalError, 1); } // Always open the dialog in case of major error but do not show the // detail button if not in debug mode. Throwable detail = internalError; return InternalErrorDialog.openQuestion(null, "Internal error", MessageFormat.format(MSG_FATAL_ERROR, new Object[] { msg }), detail, 1); } catch (Throwable th) { // Workbench may be in such bad shape (no OS handles left, out of memory, etc) // that is cannot show a message to the user. Just bail out now. System.err.println("Error while informing user about event loop exception:"); //$NON-NLS-1$ internalError.printStackTrace(); System.err.println("Dialog open exception:"); //$NON-NLS-1$ th.printStackTrace(); return true; } } private boolean openQuestion(Shell parent, String title, String message, Throwable detail, int defaultIndex) { String[] labels; if (detail == null) { labels = new String[] { IDialogConstants.YES_LABEL, IDialogConstants.NO_LABEL }; } else { labels = new String[] { IDialogConstants.YES_LABEL, IDialogConstants.NO_LABEL, IDialogConstants.SHOW_DETAILS_LABEL }; } dialog = new InternalErrorDialog(parent, title, null, message, detail, MessageDialog.QUESTION, labels, defaultIndex); if (detail != null) { dialog.setDetailButton(2); } boolean result = dialog.open() == Window.OK; dialog = null; return result; } }