Java tutorial
/******************************************************************************* * Copyright (c) 2014 Liviu Ionescu. * 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: * Liviu Ionescu - initial version *******************************************************************************/ package com.ivenix.debug.core.preferences; import org.eclipse.jface.preference.FieldEditor; import org.eclipse.jface.resource.JFaceResources; import org.eclipse.swt.SWT; import org.eclipse.swt.events.DisposeEvent; import org.eclipse.swt.events.DisposeListener; import org.eclipse.swt.layout.GridData; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Label; /** * A field editor for a string type preference. * <p> * This class may be used as is, or subclassed as required. * </p> */ public class LabelFakeFieldEditor extends FieldEditor { /** * Old text value. * * @since 3.4 this field is protected. */ protected String oldValue; /** * The text field, or <code>null</code> if none. */ Label labelField; String labelValue; /** * The error message, or <code>null</code> if none. */ private String errorMessage; /** * Creates a new string field editor */ protected LabelFakeFieldEditor() { } /** * Creates a label fake field editor. * * @param value * the content of the label field * @param labelText * the label text of the field editor * @param parent * the parent of the field editor's control * @since 2.0 */ public LabelFakeFieldEditor(String value, String labelText, Composite parent) { init("no_name", labelText); labelValue = value; errorMessage = JFaceResources.getString("StringFieldEditor.errorMessage");//$NON-NLS-1$ createControl(parent); } @Override protected void adjustForNumColumns(int numColumns) { GridData gd = (GridData) labelField.getLayoutData(); gd.horizontalSpan = numColumns - 1; // We only grab excess space if we have to // If another field editor has more columns then // we assume it is setting the width. gd.grabExcessHorizontalSpace = gd.horizontalSpan == 1; } /** * Fills this field editor's basic controls into the given parent. * <p> * The string field implementation of this <code>FieldEditor</code> * framework method contributes the text field. Subclasses may override but * must call <code>super.doFillIntoGrid</code>. * </p> */ @Override protected void doFillIntoGrid(Composite parent, int numColumns) { getLabelControl(parent); labelField = getTextControl(parent); GridData gd = new GridData(); gd.horizontalSpan = numColumns - 1; gd.horizontalAlignment = GridData.FILL; gd.grabExcessHorizontalSpace = true; labelField.setLayoutData(gd); } /* * (non-Javadoc) Method declared on FieldEditor. */ @Override protected void doLoad() { setStringValue(labelValue); } /* * (non-Javadoc) Method declared on FieldEditor. */ @Override protected void doLoadDefault() { setStringValue(labelValue); } /* * (non-Javadoc) Method declared on FieldEditor. */ @Override protected void doStore() { ; } /** * Returns the error message that will be displayed when and if an error * occurs. * * @return the error message, or <code>null</code> if none */ public String getErrorMessage() { return errorMessage; } /* * (non-Javadoc) Method declared on FieldEditor. */ @Override public int getNumberOfControls() { return 2; } /** * Returns the field editor's value. * * @return the current value */ public String getStringValue() { if (labelField != null) { return labelField.getText(); } return ""; } /** * Returns this field editor's text control. * * @return the text control, or <code>null</code> if no text field is * created yet */ protected Label getTextControl() { return labelField; } /** * Returns this field editor's text control. * <p> * The control is created if it does not yet exist * </p> * * @param parent * the parent * @return the text control */ public Label getTextControl(Composite parent) { if (labelField == null) { labelField = new Label(parent, SWT.SINGLE | SWT.BORDER); labelField.setFont(parent.getFont()); labelField.addDisposeListener(new DisposeListener() { @Override public void widgetDisposed(DisposeEvent event) { labelField = null; } }); } else { checkParent(labelField, parent); } return labelField; } /** * Sets the error message that will be displayed when and if an error * occurs. * * @param message * the error message */ public void setErrorMessage(String message) { errorMessage = message; } /* * (non-Javadoc) Method declared on FieldEditor. */ @Override public void setFocus() { if (labelField != null) { labelField.setFocus(); } } /** * Sets this field editor's value. * * @param value * the new value, or <code>null</code> meaning the empty string */ public void setStringValue(String value) { if (labelField != null) { if (value == null) { value = "";//$NON-NLS-1$ } oldValue = labelField.getText(); if (!oldValue.equals(value)) { labelField.setText(value); valueChanged(); } } } /** * Shows the error message set via <code>setErrorMessage</code>. */ public void showErrorMessage() { showErrorMessage(errorMessage); } /** * Informs this field editor's listener, if it has one, about a change to * the value (<code>VALUE</code> property) provided that the old and new * values are different. * <p> * This hook is <em>not</em> called when the text is initialized (or reset * to the default value) from the preference store. * </p> */ protected void valueChanged() { setPresentsDefaultValue(false); refreshValidState(); String newValue = labelField.getText(); if (!newValue.equals(oldValue)) { fireValueChanged(VALUE, oldValue, newValue); oldValue = newValue; } } /* * @see FieldEditor.setEnabled(boolean,Composite). */ @Override public void setEnabled(boolean enabled, Composite parent) { super.setEnabled(enabled, parent); getTextControl(parent).setEnabled(enabled); } }