org.eclipse.jdt.debug.ui/ui/org/eclipse/jdt/internal/debug/ui/jres/JREsPreferencePage.java - jdt/eclipse.jdt.debug - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2020 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
  * which accompanies this distribution, and is available at
  * https://www.eclipse.org/legal/epl-2.0/
  *
  * SPDX-License-Identifier: EPL-2.0
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.jdt.internal.debug.ui.jres;


 import java.io.File;
 import java.util.List;

 import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.core.runtime.preferences.IEclipsePreferences;
 import org.eclipse.core.runtime.preferences.InstanceScope;
 import org.eclipse.debug.internal.ui.SWTFactory;
 import org.eclipse.jdt.core.IJavaModel;
 import org.eclipse.jdt.core.JavaCore;
 import org.eclipse.jdt.debug.ui.IJavaDebugUIConstants;
 import org.eclipse.jdt.internal.debug.ui.IJavaDebugHelpContextIds;
 import org.eclipse.jdt.internal.debug.ui.JDIDebugUIPlugin;
 import org.eclipse.jdt.internal.launching.StandardVMType;
 import org.eclipse.jdt.launching.AbstractVMInstall;
 import org.eclipse.jdt.launching.IVMInstall;
 import org.eclipse.jdt.launching.IVMInstallType;
 import org.eclipse.jdt.launching.JavaRuntime;
 import org.eclipse.jdt.launching.LibraryLocation;
 import org.eclipse.jface.dialogs.ErrorDialog;
 import org.eclipse.jface.dialogs.IDialogSettings;
 import org.eclipse.jface.dialogs.IMessageProvider;
 import org.eclipse.jface.dialogs.MessageDialog;
 import org.eclipse.jface.preference.PreferencePage;
 import org.eclipse.jface.viewers.ISelectionChangedListener;
 import org.eclipse.jface.viewers.SelectionChangedEvent;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.custom.BusyIndicator;
 import org.eclipse.swt.events.SelectionEvent;
 import org.eclipse.swt.events.SelectionListener;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Link;
 import org.eclipse.ui.IWorkbench;
 import org.eclipse.ui.IWorkbenchPreferencePage;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.preferences.IWorkbenchPreferenceContainer;

 /**
  * The Installed JREs preference page.
  *
  * @since 3.0
  */
 public class JREsPreferencePage extends PreferencePage implements IWorkbenchPreferencePage {

 	/**
 	 * ID for the page
 	 *
 	 * @since 3.5
 	 */
 	public static final String ID = "org.eclipse.jdt.debug.ui.preferences.VMPreferencePage"; //$NON-NLS-1$

 	// JRE Block
 	private InstalledJREsBlock fJREBlock;
 	private Link fCompliance;

 	/**
 	 * Constructor
 	 */
 	public JREsPreferencePage() {
 		super(JREMessages.JREsPreferencePage_1);
 	}

 	/* (non-Javadoc)
 	 * @see org.eclipse.ui.IWorkbenchPreferencePage#init(org.eclipse.ui.IWorkbench)
 	 */
 	@Override
 	public void init(IWorkbench workbench) {
 	}

 	/**
 	 * Find & verify the default VM.
 	 */
 	private void initDefaultVM() {
 		IVMInstall realDefault= JavaRuntime.getDefaultVMInstall();
 		if (realDefault != null) {
 			IVMInstall[] vms= fJREBlock.getJREs();
 			for (int i = 0; i < vms.length; i++) {
 				IVMInstall fakeVM= vms[i];
 				if (fakeVM.equals(realDefault)) {
 					verifyDefaultVM(fakeVM);
 					break;
 				}
 			}
 		}
 	}

 	/* (non-Javadoc)
 	 * @see org.eclipse.jface.preference.PreferencePage#createContents(org.eclipse.swt.widgets.Composite)
 	 */
 	@Override
 	protected Control createContents(Composite ancestor) {
 		initializeDialogUnits(ancestor);

 		noDefaultButton();

 		GridLayout layout= new GridLayout();
 		layout.numColumns= 1;
 		layout.marginHeight = 0;
 		layout.marginWidth = 0;
 		ancestor.setLayout(layout);

 		SWTFactory.createWrapLabel(ancestor, JREMessages.JREsPreferencePage_2, 1, 300);
 		SWTFactory.createVerticalSpacer(ancestor, 1);

 		fJREBlock = new InstalledJREsBlock();
 		fJREBlock.createControl(ancestor);
 		Control control = fJREBlock.getControl();
 		GridData data = new GridData(GridData.FILL_BOTH);
 		data.horizontalSpan = 1;
 		control.setLayoutData(data);

 		fJREBlock.restoreColumnSettings(JDIDebugUIPlugin.getDefault().getDialogSettings(), IJavaDebugHelpContextIds.JRE_PREFERENCE_PAGE);

 		fCompliance = new Link(ancestor, SWT.NONE);
 		fCompliance.setText(JREMessages.JREsPreferencePage_14);
 		fCompliance.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
 		fCompliance.setVisible(false);
 		fCompliance.addSelectionListener(new SelectionListener() {
 			@Override
 			public void widgetDefaultSelected(SelectionEvent e) {}
 			@Override
 			public void widgetSelected(SelectionEvent e) {openCompliancePreferencePage();}
 		});
 		PlatformUI.getWorkbench().getHelpSystem().setHelp(ancestor, IJavaDebugHelpContextIds.JRE_PREFERENCE_PAGE);
 		initDefaultVM();
 		fJREBlock.initializeTimeStamp();
 		fJREBlock.addSelectionChangedListener(new ISelectionChangedListener() {
 			@Override
 			public void selectionChanged(SelectionChangedEvent event) {
 				IVMInstall install = getCurrentDefaultVM();
 				if (install == null) {
 					setValid(false);
 					if(fJREBlock.getJREs().length < 1) {
 						setErrorMessage(JREMessages.JREsPreferencePage_3);
 					}
 					else {
 						setErrorMessage(JREMessages.JREsPreferencePage_13);
 					}
 				} else {
 					//if we change the VM make sure the compliance level supports
 					//generated class files
 					validateComplianceAndJRE(install);
 					setValid(true);
 					setErrorMessage(null);
 				}
 			}
 		});
 		applyDialogFont(ancestor);
 		return ancestor;
 	}

 	/* (non-Javadoc)
 	 * @see org.eclipse.jface.preference.PreferencePage#isValid()
 	 */
 	@Override
 	public boolean isValid() {
 		validateComplianceAndJRE(getCurrentDefaultVM());
 		return super.isValid();
 	}

 	private void validateComplianceAndJRE(IVMInstall vmInstall) {
 		String compliance = getCurrentCompilerCompliance();
 		if (!supportsCurrentCompliance(vmInstall, compliance)) {
 			setMessage(NLS.bind(JREMessages.JREsPreferencePage_0, new String[] {compliance}), IMessageProvider.WARNING);
 			fCompliance.setVisible(true);
 		}
 		else {
 			List<String> allVersions = JavaCore.getAllVersions();
 			String latest = allVersions.get(allVersions.size() - 1);
 			String vmver = null;
 			if (vmInstall instanceof AbstractVMInstall) {
 				AbstractVMInstall vm = (AbstractVMInstall) vmInstall;
 				vmver = vm.getJavaVersion();
 			}
 			if (vmver == null) {
 				IVMInstallType vmType = vmInstall.getVMInstallType();
 				if ( vmType instanceof StandardVMType) {
 					vmver = ((StandardVMType) vmType).readReleaseVersion(vmInstall.getInstallLocation());
 				}
 			}
 			if (vmver != null && vmver.length() != 0 && JavaCore.compareJavaVersions(vmver, latest) > 0) {
 				setMessage(NLS.bind(JREMessages.JREsPreferencePage_9, new String[] { compliance }), IMessageProvider.WARNING);
 				fCompliance.setVisible(true);
 			} else {
 				setMessage(null);
 				fCompliance.setVisible(false);
 			}
 		}
 	}

 	/**
 	 * Opens the <code>CompliancePreferencePage</code>
 	 * @since 3.3
 	 */
 	private void openCompliancePreferencePage() {
 		String compliancepage = "org.eclipse.jdt.ui.preferences.CompliancePreferencePage"; //$NON-NLS-1$
 		IWorkbenchPreferenceContainer wpc = (IWorkbenchPreferenceContainer)getContainer();
 		if (wpc != null) {
 			wpc.openPage(compliancepage, null);
 		} else {
 			SWTFactory.showPreferencePage(compliancepage);
 		}
 	}

 	/**
 	 * @return the current compiler compliance level
 	 * @since 3.3
 	 */
 	private String getCurrentCompilerCompliance() {
 		IEclipsePreferences setting = InstanceScope.INSTANCE.getNode(JavaCore.PLUGIN_ID);
 		if(getContainer() instanceof IWorkbenchPreferenceContainer) {
 			IEclipsePreferences wcs = ((IWorkbenchPreferenceContainer)getContainer()).getWorkingCopyManager().getWorkingCopy(setting);
 			return wcs.get(JavaCore.COMPILER_COMPLIANCE, JavaCore.getDefaultOptions().get(JavaCore.COMPILER_COMPLIANCE));
 		}
 			return JavaCore.getOption(JavaCore.COMPILER_COMPLIANCE);

 	}

 	/**
 	 * Determines if the vm version will run the currently compiled code based on the compiler compliance lvl
 	 * @param vm the vm install
 	 * @param compliance the current compiler compliance level
 	 * @return true if the selected vm will run the current code, false otherwise
 	 * @since 3.3
 	 */
 	private boolean supportsCurrentCompliance(IVMInstall vm, String compliance) {
 		if(vm instanceof AbstractVMInstall) {
 			AbstractVMInstall install = (AbstractVMInstall) vm;
 			String vmver = install.getJavaVersion();
 			if(vmver == null) {
 				//if we cannot get a version from the VM we must return true, and let the runtime
 				//error sort it out
 				return true;
 			}
 			int val = compliance.compareTo(vmver);
 			return  val < 0 || val == 0;
 		}
 		return false;
 	}

 	/* (non-Javadoc)
 	 * @see org.eclipse.jface.preference.IPreferencePage#performOk()
 	 */
 	@Override
 	public boolean performOk() {
 		final boolean[] canceled = new boolean[] {false};
 		BusyIndicator.showWhile(null, new Runnable() {
 			@Override
 			public void run() {
 				IVMInstall defaultVM = getCurrentDefaultVM();
 				IVMInstall[] vms = fJREBlock.getJREs();
 				JREsUpdater updater = new JREsUpdater();
 				if (!updater.updateJRESettings(vms, defaultVM)) {
 					canceled[0] = true;
 				}
 			}
 		});

 		if(canceled[0]) {
 			return false;
 		}

 		// save column widths
 		IDialogSettings settings = JDIDebugUIPlugin.getDefault().getDialogSettings();
 		fJREBlock.saveColumnSettings(settings, IJavaDebugHelpContextIds.JRE_PREFERENCE_PAGE);
 		fJREBlock.initializeTimeStamp();

 		return super.performOk();
 	}

 	protected IJavaModel getJavaModel() {
 		return JavaCore.create(ResourcesPlugin.getWorkspace().getRoot());
 	}

 	/**
 	 * Verify that the specified VM can be a valid default VM.  This amounts to verifying
 	 * that all of the VM's library locations exist on the file system.  If this fails,
 	 * remove the VM from the table and try to set another default.
 	 */
 	private void verifyDefaultVM(IVMInstall vm) {
 		if (vm != null) {

 			// Verify that all of the specified VM's library locations actually exist
 			LibraryLocation[] locations= JavaRuntime.getLibraryLocations(vm);
 			boolean exist = true;
 			for (int i = 0; i < locations.length; i++) {
 				exist = exist && new File(locations[i].getSystemLibraryPath().toOSString()).exists();
 			}

 			// If all library locations exist, check the corresponding entry in the list,
 			// otherwise remove the VM
 			if (exist) {
 				fJREBlock.setCheckedJRE(vm);
 			} else {
 				fJREBlock.removeJREs(new IVMInstall[]{vm});
 				IVMInstall def = JavaRuntime.getDefaultVMInstall();
 				if (def == null) {
 					fJREBlock.setCheckedJRE(null);
 				} else {
 					fJREBlock.setCheckedJRE(def);
 				}
 				ErrorDialog.openError(getControl().getShell(), JREMessages.JREsPreferencePage_1, JREMessages.JREsPreferencePage_10, new Status(IStatus.ERROR, IJavaDebugUIConstants.PLUGIN_ID, IJavaDebugUIConstants.INTERNAL_ERROR, "JRE removed", null)); //   //$NON-NLS-1$
 				return;
 			}
 		} else {
 			fJREBlock.setCheckedJRE(null);
 		}
 	}

 	private IVMInstall getCurrentDefaultVM() {
 		return fJREBlock.getCheckedJRE();
 	}

 	/* (non-Javadoc)
 	 * @see org.eclipse.jface.dialogs.DialogPage#dispose()
 	 */
 	@Override
 	public void dispose() {
 		super.dispose();
 		if (fJREBlock != null) {
 			fJREBlock.dispose();
 		}
 	}

 	/*
 	 * @see org.eclipse.jface.preference.PreferencePage#okToLeave()
 	 */
 	@Override
 	public boolean okToLeave() {
 		if (fJREBlock != null && fJREBlock.hasChangesInDialog()) {
 			String title = JREMessages.JREsPreferencePage_4;
 			String message = JREMessages.JREsPreferencePage_5;
 			String[] buttonLabels = new String[] { JREMessages.JREsPreferencePage_6, JREMessages.JREsPreferencePage_7,
 					JREMessages.JREsPreferencePage_8 };
 			MessageDialog dialog = new MessageDialog(getShell(), title, null, message, MessageDialog.QUESTION, buttonLabels, 0);
 			int res = dialog.open();
 			switch (res) {
 			case 0:
 				// apply
 				return performOk() && super.okToLeave();
 			case 1:
 				// discard
 				fJREBlock.fillWithWorkspaceJREs();
 				fJREBlock.restoreColumnSettings(JDIDebugUIPlugin.getDefault().getDialogSettings(), IJavaDebugHelpContextIds.JRE_PREFERENCE_PAGE);
 				initDefaultVM();
 				fJREBlock.initializeTimeStamp();
 				break;
 			default:
 				// apply later
 				break;
 			}
 		}
 		return super.okToLeave();
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2020 IBM Corporation and others.
	*
	* This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License 2.0
	* which accompanies this distribution, and is available at
	* https://www.eclipse.org/legal/epl-2.0/
	*
	* SPDX-License-Identifier: EPL-2.0
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/
	package org.eclipse.jdt.internal.debug.ui.jres;


	import java.io.File;
	import java.util.List;

	import org.eclipse.core.resources.ResourcesPlugin;
	import org.eclipse.core.runtime.IStatus;
	import org.eclipse.core.runtime.Status;
	import org.eclipse.core.runtime.preferences.IEclipsePreferences;
	import org.eclipse.core.runtime.preferences.InstanceScope;
	import org.eclipse.debug.internal.ui.SWTFactory;
	import org.eclipse.jdt.core.IJavaModel;
	import org.eclipse.jdt.core.JavaCore;
	import org.eclipse.jdt.debug.ui.IJavaDebugUIConstants;
	import org.eclipse.jdt.internal.debug.ui.IJavaDebugHelpContextIds;
	import org.eclipse.jdt.internal.debug.ui.JDIDebugUIPlugin;
	import org.eclipse.jdt.internal.launching.StandardVMType;
	import org.eclipse.jdt.launching.AbstractVMInstall;
	import org.eclipse.jdt.launching.IVMInstall;
	import org.eclipse.jdt.launching.IVMInstallType;
	import org.eclipse.jdt.launching.JavaRuntime;
	import org.eclipse.jdt.launching.LibraryLocation;
	import org.eclipse.jface.dialogs.ErrorDialog;
	import org.eclipse.jface.dialogs.IDialogSettings;
	import org.eclipse.jface.dialogs.IMessageProvider;
	import org.eclipse.jface.dialogs.MessageDialog;
	import org.eclipse.jface.preference.PreferencePage;
	import org.eclipse.jface.viewers.ISelectionChangedListener;
	import org.eclipse.jface.viewers.SelectionChangedEvent;
	import org.eclipse.osgi.util.NLS;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.custom.BusyIndicator;
	import org.eclipse.swt.events.SelectionEvent;
	import org.eclipse.swt.events.SelectionListener;
	import org.eclipse.swt.layout.GridData;
	import org.eclipse.swt.layout.GridLayout;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Control;
	import org.eclipse.swt.widgets.Link;
	import org.eclipse.ui.IWorkbench;
	import org.eclipse.ui.IWorkbenchPreferencePage;
	import org.eclipse.ui.PlatformUI;
	import org.eclipse.ui.preferences.IWorkbenchPreferenceContainer;

	/**
	* The Installed JREs preference page.
	*
	* @since 3.0
	*/
	public class JREsPreferencePage extends PreferencePage implements IWorkbenchPreferencePage {

	/**
	* ID for the page
	*
	* @since 3.5
	*/
	public static final String ID = "org.eclipse.jdt.debug.ui.preferences.VMPreferencePage"; //$NON-NLS-1$

	// JRE Block
	private InstalledJREsBlock fJREBlock;
	private Link fCompliance;

	/**
	* Constructor
	*/
	public JREsPreferencePage() {
	super(JREMessages.JREsPreferencePage_1);
	}

	/* (non-Javadoc)
	* @see org.eclipse.ui.IWorkbenchPreferencePage#init(org.eclipse.ui.IWorkbench)
	*/
	@Override
	public void init(IWorkbench workbench) {
	}

	/**
	* Find & verify the default VM.
	*/
	private void initDefaultVM() {
	IVMInstall realDefault= JavaRuntime.getDefaultVMInstall();
	if (realDefault != null) {
	IVMInstall[] vms= fJREBlock.getJREs();
	for (int i = 0; i < vms.length; i++) {
	IVMInstall fakeVM= vms[i];
	if (fakeVM.equals(realDefault)) {
	verifyDefaultVM(fakeVM);
	break;
	}
	}
	}
	}

	/* (non-Javadoc)
	* @see org.eclipse.jface.preference.PreferencePage#createContents(org.eclipse.swt.widgets.Composite)
	*/
	@Override
	protected Control createContents(Composite ancestor) {
	initializeDialogUnits(ancestor);

	noDefaultButton();

	GridLayout layout= new GridLayout();
	layout.numColumns= 1;
	layout.marginHeight = 0;
	layout.marginWidth = 0;
	ancestor.setLayout(layout);

	SWTFactory.createWrapLabel(ancestor, JREMessages.JREsPreferencePage_2, 1, 300);
	SWTFactory.createVerticalSpacer(ancestor, 1);

	fJREBlock = new InstalledJREsBlock();
	fJREBlock.createControl(ancestor);
	Control control = fJREBlock.getControl();
	GridData data = new GridData(GridData.FILL_BOTH);
	data.horizontalSpan = 1;
	control.setLayoutData(data);

	fJREBlock.restoreColumnSettings(JDIDebugUIPlugin.getDefault().getDialogSettings(), IJavaDebugHelpContextIds.JRE_PREFERENCE_PAGE);

	fCompliance = new Link(ancestor, SWT.NONE);
	fCompliance.setText(JREMessages.JREsPreferencePage_14);
	fCompliance.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
	fCompliance.setVisible(false);
	fCompliance.addSelectionListener(new SelectionListener() {
	@Override
	public void widgetDefaultSelected(SelectionEvent e) {}
	@Override
	public void widgetSelected(SelectionEvent e) {openCompliancePreferencePage();}
	});
	PlatformUI.getWorkbench().getHelpSystem().setHelp(ancestor, IJavaDebugHelpContextIds.JRE_PREFERENCE_PAGE);
	initDefaultVM();
	fJREBlock.initializeTimeStamp();
	fJREBlock.addSelectionChangedListener(new ISelectionChangedListener() {
	@Override
	public void selectionChanged(SelectionChangedEvent event) {
	IVMInstall install = getCurrentDefaultVM();
	if (install == null) {
	setValid(false);
	if(fJREBlock.getJREs().length < 1) {
	setErrorMessage(JREMessages.JREsPreferencePage_3);
	}
	else {
	setErrorMessage(JREMessages.JREsPreferencePage_13);
	}
	} else {
	//if we change the VM make sure the compliance level supports
	//generated class files
	validateComplianceAndJRE(install);
	setValid(true);
	setErrorMessage(null);
	}
	}
	});
	applyDialogFont(ancestor);
	return ancestor;
	}

	/* (non-Javadoc)
	* @see org.eclipse.jface.preference.PreferencePage#isValid()
	*/
	@Override
	public boolean isValid() {
	validateComplianceAndJRE(getCurrentDefaultVM());
	return super.isValid();
	}

	private void validateComplianceAndJRE(IVMInstall vmInstall) {
	String compliance = getCurrentCompilerCompliance();
	if (!supportsCurrentCompliance(vmInstall, compliance)) {
	setMessage(NLS.bind(JREMessages.JREsPreferencePage_0, new String[] {compliance}), IMessageProvider.WARNING);
	fCompliance.setVisible(true);
	}
	else {
	List<String> allVersions = JavaCore.getAllVersions();
	String latest = allVersions.get(allVersions.size() - 1);
	String vmver = null;
	if (vmInstall instanceof AbstractVMInstall) {
	AbstractVMInstall vm = (AbstractVMInstall) vmInstall;
	vmver = vm.getJavaVersion();
	}
	if (vmver == null) {
	IVMInstallType vmType = vmInstall.getVMInstallType();
	if ( vmType instanceof StandardVMType) {
	vmver = ((StandardVMType) vmType).readReleaseVersion(vmInstall.getInstallLocation());
	}
	}
	if (vmver != null && vmver.length() != 0 && JavaCore.compareJavaVersions(vmver, latest) > 0) {
	setMessage(NLS.bind(JREMessages.JREsPreferencePage_9, new String[] { compliance }), IMessageProvider.WARNING);
	fCompliance.setVisible(true);
	} else {
	setMessage(null);
	fCompliance.setVisible(false);
	}
	}
	}

	/**
	* Opens the <code>CompliancePreferencePage</code>
	* @since 3.3
	*/
	private void openCompliancePreferencePage() {
	String compliancepage = "org.eclipse.jdt.ui.preferences.CompliancePreferencePage"; //$NON-NLS-1$
	IWorkbenchPreferenceContainer wpc = (IWorkbenchPreferenceContainer)getContainer();
	if (wpc != null) {
	wpc.openPage(compliancepage, null);
	} else {
	SWTFactory.showPreferencePage(compliancepage);
	}
	}

	/**
	* @return the current compiler compliance level
	* @since 3.3
	*/
	private String getCurrentCompilerCompliance() {
	IEclipsePreferences setting = InstanceScope.INSTANCE.getNode(JavaCore.PLUGIN_ID);
	if(getContainer() instanceof IWorkbenchPreferenceContainer) {
	IEclipsePreferences wcs = ((IWorkbenchPreferenceContainer)getContainer()).getWorkingCopyManager().getWorkingCopy(setting);
	return wcs.get(JavaCore.COMPILER_COMPLIANCE, JavaCore.getDefaultOptions().get(JavaCore.COMPILER_COMPLIANCE));
	}
	return JavaCore.getOption(JavaCore.COMPILER_COMPLIANCE);

	}

	/**
	* Determines if the vm version will run the currently compiled code based on the compiler compliance lvl
	* @param vm the vm install
	* @param compliance the current compiler compliance level
	* @return true if the selected vm will run the current code, false otherwise
	* @since 3.3
	*/
	private boolean supportsCurrentCompliance(IVMInstall vm, String compliance) {
	if(vm instanceof AbstractVMInstall) {
	AbstractVMInstall install = (AbstractVMInstall) vm;
	String vmver = install.getJavaVersion();
	if(vmver == null) {
	//if we cannot get a version from the VM we must return true, and let the runtime
	//error sort it out
	return true;
	}
	int val = compliance.compareTo(vmver);
	return val < 0 \|\| val == 0;
	}
	return false;
	}

	/* (non-Javadoc)
	* @see org.eclipse.jface.preference.IPreferencePage#performOk()
	*/
	@Override
	public boolean performOk() {
	final boolean[] canceled = new boolean[] {false};
	BusyIndicator.showWhile(null, new Runnable() {
	@Override
	public void run() {
	IVMInstall defaultVM = getCurrentDefaultVM();
	IVMInstall[] vms = fJREBlock.getJREs();
	JREsUpdater updater = new JREsUpdater();
	if (!updater.updateJRESettings(vms, defaultVM)) {
	canceled[0] = true;
	}
	}
	});

	if(canceled[0]) {
	return false;
	}

	// save column widths
	IDialogSettings settings = JDIDebugUIPlugin.getDefault().getDialogSettings();
	fJREBlock.saveColumnSettings(settings, IJavaDebugHelpContextIds.JRE_PREFERENCE_PAGE);
	fJREBlock.initializeTimeStamp();

	return super.performOk();
	}

	protected IJavaModel getJavaModel() {
	return JavaCore.create(ResourcesPlugin.getWorkspace().getRoot());
	}

	/**
	* Verify that the specified VM can be a valid default VM. This amounts to verifying
	* that all of the VM's library locations exist on the file system. If this fails,
	* remove the VM from the table and try to set another default.
	*/
	private void verifyDefaultVM(IVMInstall vm) {
	if (vm != null) {

	// Verify that all of the specified VM's library locations actually exist
	LibraryLocation[] locations= JavaRuntime.getLibraryLocations(vm);
	boolean exist = true;
	for (int i = 0; i < locations.length; i++) {
	exist = exist && new File(locations[i].getSystemLibraryPath().toOSString()).exists();
	}

	// If all library locations exist, check the corresponding entry in the list,
	// otherwise remove the VM
	if (exist) {
	fJREBlock.setCheckedJRE(vm);
	} else {
	fJREBlock.removeJREs(new IVMInstall[]{vm});
	IVMInstall def = JavaRuntime.getDefaultVMInstall();
	if (def == null) {
	fJREBlock.setCheckedJRE(null);
	} else {
	fJREBlock.setCheckedJRE(def);
	}
	ErrorDialog.openError(getControl().getShell(), JREMessages.JREsPreferencePage_1, JREMessages.JREsPreferencePage_10, new Status(IStatus.ERROR, IJavaDebugUIConstants.PLUGIN_ID, IJavaDebugUIConstants.INTERNAL_ERROR, "JRE removed", null)); // //$NON-NLS-1$
	return;
	}
	} else {
	fJREBlock.setCheckedJRE(null);
	}
	}

	private IVMInstall getCurrentDefaultVM() {
	return fJREBlock.getCheckedJRE();
	}

	/* (non-Javadoc)
	* @see org.eclipse.jface.dialogs.DialogPage#dispose()
	*/
	@Override
	public void dispose() {
	super.dispose();
	if (fJREBlock != null) {
	fJREBlock.dispose();
	}
	}

	/*
	* @see org.eclipse.jface.preference.PreferencePage#okToLeave()
	*/
	@Override
	public boolean okToLeave() {
	if (fJREBlock != null && fJREBlock.hasChangesInDialog()) {
	String title = JREMessages.JREsPreferencePage_4;
	String message = JREMessages.JREsPreferencePage_5;
	String[] buttonLabels = new String[] { JREMessages.JREsPreferencePage_6, JREMessages.JREsPreferencePage_7,
	JREMessages.JREsPreferencePage_8 };
	MessageDialog dialog = new MessageDialog(getShell(), title, null, message, MessageDialog.QUESTION, buttonLabels, 0);
	int res = dialog.open();
	switch (res) {
	case 0:
	// apply
	return performOk() && super.okToLeave();
	case 1:
	// discard
	fJREBlock.fillWithWorkspaceJREs();
	fJREBlock.restoreColumnSettings(JDIDebugUIPlugin.getDefault().getDialogSettings(), IJavaDebugHelpContextIds.JRE_PREFERENCE_PAGE);
	initDefaultVM();
	fJREBlock.initializeTimeStamp();
	break;
	default:
	// apply later
	break;
	}
	}
	return super.okToLeave();
	}
	}