jFace: ErrorDialog

By using ErrorDialog class, we can show one (or) more errors to users. If the error has more information to display, then a 'Details' button is added automatically. When user clicks on 'Details' button, then it displays the complete information to user.

ErrorDialog class provides following constructor to instantiate an object.

ErrorDialog(Shell parentShell, String dialogTitle, String message, IStatus status, int displayMask)

Following table summarizes the parameters.

Parameter	Description
parentShell	the shell under which to create this dialog
dialogTitle	the title to use for this dialog, or null to indicate that the default title should be used
message	the message to show in this dialog, or null to indicate that the error's message should be shown as the primary message
status	the error to show to the user
displayMask	the mask to use to filter the displaying of child items, as per IStatus.matches

Note

a.   ErrorDialog don’t has any visual representation, unless you call open() method on it.

b.   The error dialog will only be displayed if there is at least one child status matching the mask.

What is IStatus object?

IStatus object represents the outcome of an operation. IStatus object carries following information.

a.   plug-in identifier (required)

b.   severity (required)

c.    status code (required)

d.   message (required) - localized to current locale

e.   exception (optional) - for problems stemming from a failure at a lower level

IStatus class provides following constants to specify the type of message.

Constant	Description
static int CANCEL	Status represents a cancelation, bitmask value is 8.
static int ERROR	Status represents an error, bitmask value is 4.
static int INFO	Status represents information, bitmask value is 1.
static int OK	Status represents normal case, bitmask value is 0.
static int WARNING	Status represents warning, bitmask value is 2.

Note

Some status objects, known as multi-statuses, have other status objects as children. SWT provides MultiStatus class, it implements IStatus interface.

package test;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.MultiStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jface.dialogs.ErrorDialog;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class Test {
 private static MultiStatus getMultiStatus(String msg, Throwable t) {

  List<Status> statuses = new ArrayList<Status>();
  StackTraceElement[] stackTraces = t.getStackTrace();

  for (StackTraceElement stackTrace : stackTraces) {
   Status status = new Status(IStatus.ERROR, Test.class.getName(), stackTrace.toString());
   statuses.add(status);
  }

  MultiStatus ms = new MultiStatus(Test.class.getName(), IStatus.ERROR, statuses.toArray(new Status[] {}),
    t.toString(), t);
  return ms;
 }

 public static void main(String[] args) {
  System.out.println(System.getProperty("user.home"));

  /* Instantiate Display object, it represents SWT session */
  Display display = new Display();

  /*
   * Define Shell, it represent a window, You can add more than one shell
   * to Display
   */
  Shell shell = new Shell(display);

  /* Open shell window */
  shell.open();

  try {
   String s = null;
   s.toCharArray();
  } catch (Exception e) {
   String message = e.getMessage();
   MultiStatus multiStatus = getMultiStatus(message, e);

   ErrorDialog dialog = new ErrorDialog(Display.getDefault().getActiveShell(), "Demo Error Dialog",
     "NullPointerException", multiStatus, IStatus.ERROR);
   dialog.open();
  }

  /*
   * Run the event dispatching loop until an exit condition occurs, which
   * is typically when the main shell window is closed by the user.
   */

  while (!shell.isDisposed()) {
   if (!display.readAndDispatch())
    display.sleep();
  }

  /* Dispose the display */
  display.dispose();
 }
}

Run above application, you can able to see following window.

ErrorDialog class provides following convenient methods to open an error dialog.

static int openError(Shell parent, String dialogTitle, String message, IStatus status)

Opens an error dialog to display the given error.

static int openError(Shell parentShell, String title, String message, IStatus status, int displayMask)

Opens an error dialog to display the given error.

Ex:

String message = e.getMessage();

MultiStatus multiStatus = getMultiStatus(message, e);

ErrorDialog.openError(Display.getDefault().getActiveShell(), "Demo Error Dialog", message, multiStatus);

Following is the complete working application.

package test;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.MultiStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jface.dialogs.ErrorDialog;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class Test {
 private static MultiStatus getMultiStatus(String msg, Throwable t) {

  List<Status> statuses = new ArrayList<Status>();
  StackTraceElement[] stackTraces = t.getStackTrace();

  for (StackTraceElement stackTrace : stackTraces) {
   Status status = new Status(IStatus.ERROR, Test.class.getName(), stackTrace.toString());
   statuses.add(status);
  }

  MultiStatus ms = new MultiStatus(Test.class.getName(), IStatus.ERROR, statuses.toArray(new Status[] {}),
    t.toString(), t);
  return ms;
 }

 public static void main(String[] args) {
  System.out.println(System.getProperty("user.home"));

  /* Instantiate Display object, it represents SWT session */
  Display display = new Display();

  /*
   * Define Shell, it represent a window, You can add more than one shell
   * to Display
   */
  Shell shell = new Shell(display);

  /* Open shell window */
  shell.open();

  try {
   String s = null;
   s.toCharArray();
  } catch (Exception e) {
   String message = e.getMessage();
   MultiStatus multiStatus = getMultiStatus(message, e);

   ErrorDialog.openError(Display.getDefault().getActiveShell(), "Demo Error Dialog", message, multiStatus);
  }

  /*
   * Run the event dispatching loop until an exit condition occurs, which
   * is typically when the main shell window is closed by the user.
   */

  while (!shell.isDisposed()) {
   if (!display.readAndDispatch())
    display.sleep();
  }

  /* Dispose the display */
  display.dispose();
 }
}

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