Java tutorial
/******************************************************************************* * Copyright (c) 2009-2013 SKRATCHDOT.COM * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * JEFF |:at:| SKRATCHDOT |:dot:| COM *******************************************************************************/ package com.skratchdot.electribe.fileexplorer.preferences; import java.util.*; import org.eclipse.jface.dialogs.IDialogConstants; import org.eclipse.jface.preference.FieldEditor; import org.eclipse.swt.SWT; import org.eclipse.swt.events.SelectionAdapter; import org.eclipse.swt.events.SelectionEvent; import org.eclipse.swt.layout.GridData; import org.eclipse.swt.layout.GridLayout; import org.eclipse.swt.widgets.Button; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Label; import org.eclipse.swt.widgets.List; import org.eclipse.swt.widgets.Text; /** * A field editor for displaying and storing a list of strings. * Buttons are provided for adding items to the list and removing * items from the list. */ public class AddRemoveListFieldEditor extends FieldEditor { private static final String DEFAULT_ADD_LABEL = "Add"; private static final String DEFAULT_REMOVE_LABEL = "Remove selection"; private static final String DEFAULT_SEPERATOR = ";"; private static final int VERTICAL_DIALOG_UNITS_PER_CHAR = 8; private static final int LIST_HEIGHT_IN_CHARS = 10; private static final int LIST_HEIGHT_IN_DLUS = LIST_HEIGHT_IN_CHARS * VERTICAL_DIALOG_UNITS_PER_CHAR; // The top-level control for the field editor. private Composite top; // The list of tags. private List list; // The text field for inputting new tags. private Text textField; // The button for adding the contents of // the text field to the list. private Button add; // The button for removing the currently-selected list item. private Button remove; // The string used to seperate list items // in a single String representation. private String seperator = DEFAULT_SEPERATOR; public AddRemoveListFieldEditor(String name, String labelText, Composite parent) { super(name, labelText, parent); } public AddRemoveListFieldEditor(String name, String labelText, String addButtonText, String removeButtonText, Composite parent) { super(name, labelText, parent); setAddButtonText(addButtonText); setRemoveButtonText(removeButtonText); } /** * @see org.eclipse.jface.preference.FieldEditor#adjustForNumColumns(int) */ protected void adjustForNumColumns(int numColumns) { ((GridData) top.getLayoutData()).horizontalSpan = numColumns; } /** * @see org.eclipse.jface.preference.FieldEditor#doFillIntoGrid * (Composite, int) */ protected void doFillIntoGrid(Composite parent, int numColumns) { top = parent; GridData gd = new GridData(GridData.FILL_HORIZONTAL); gd.horizontalSpan = numColumns; top.setLayoutData(gd); Label label = getLabelControl(top); GridData labelData = new GridData(); labelData.horizontalSpan = numColumns; label.setLayoutData(labelData); list = new List(top, SWT.BORDER); // Create a grid data that takes up the extra // space in the dialog and spans both columns. GridData listData = new GridData(GridData.FILL_HORIZONTAL); listData.heightHint = convertVerticalDLUsToPixels(list, LIST_HEIGHT_IN_DLUS); listData.horizontalSpan = numColumns; list.setLayoutData(listData); list.addSelectionListener(new SelectionAdapter() { public void widgetSelected(SelectionEvent e) { selectionChanged(); } }); // Create a composite for the add and remove // buttons and the input text field. Composite addRemoveGroup = new Composite(top, SWT.NONE); GridData addRemoveData = new GridData(GridData.FILL_HORIZONTAL); addRemoveData.horizontalSpan = numColumns; addRemoveGroup.setLayoutData(addRemoveData); GridLayout addRemoveLayout = new GridLayout(); addRemoveLayout.numColumns = numColumns; addRemoveLayout.marginHeight = 0; addRemoveLayout.marginWidth = 0; addRemoveGroup.setLayout(addRemoveLayout); // Create a composite for the add and remove buttons. Composite buttonGroup = new Composite(addRemoveGroup, SWT.NONE); buttonGroup.setLayoutData(new GridData()); GridLayout buttonLayout = new GridLayout(); buttonLayout.marginHeight = 0; buttonLayout.marginWidth = 0; buttonGroup.setLayout(buttonLayout); // Create the add button. add = new Button(buttonGroup, SWT.NONE); add.setText(DEFAULT_ADD_LABEL); add.addSelectionListener(new SelectionAdapter() { public void widgetSelected(SelectionEvent e) { add(); } }); GridData addData = new GridData(GridData.FILL_HORIZONTAL); addData.widthHint = convertHorizontalDLUsToPixels(add, IDialogConstants.BUTTON_WIDTH); add.setLayoutData(addData); // Create the remove button. remove = new Button(buttonGroup, SWT.NONE); remove.setEnabled(false); remove.setText(DEFAULT_REMOVE_LABEL); remove.addSelectionListener(new SelectionAdapter() { public void widgetSelected(SelectionEvent e) { list.remove(list.getSelectionIndex()); selectionChanged(); } }); GridData removeData = new GridData(GridData.FILL_HORIZONTAL); removeData.widthHint = convertHorizontalDLUsToPixels(remove, IDialogConstants.BUTTON_WIDTH); remove.setLayoutData(removeData); // Create the text field. textField = new Text(addRemoveGroup, SWT.BORDER); GridData textData = new GridData(GridData.FILL_HORIZONTAL); textData.horizontalSpan = numColumns - 1; textData.verticalAlignment = GridData.BEGINNING; textField.setLayoutData(textData); } /** * @see org.eclipse.jface.preference.FieldEditor#doLoad() */ protected void doLoad() { String items = getPreferenceStore().getString(getPreferenceName()); setList(items); } /** * @see org.eclipse.jface.preference.FieldEditor#doLoadDefault() */ protected void doLoadDefault() { String items = getPreferenceStore().getDefaultString(getPreferenceName()); setList(items); } // Parses the string into seperate list items and adds them to the list. private void setList(String items) { String[] itemArray = parseString(items); list.setItems(itemArray); } /** * @see org.eclipse.jface.preference.FieldEditor#doStore() */ protected void doStore() { String s = createListString(list.getItems()); if (s != null) getPreferenceStore().setValue(getPreferenceName(), s); } /** * @see org.eclipse.jface.preference.FieldEditor#getNumberOfControls() */ public int getNumberOfControls() { // The button composite and the text field. return 2; } // Adds the string in the text field to the list. private void add() { String tag = textField.getText(); if (tag != null && tag.length() > 0) list.add(tag); textField.setText(""); } /** * Sets the label for the button that adds * the contents of the text field to the list. */ public void setAddButtonText(String text) { add.setText(text); } /** * Sets the label for the button that removes * the selected item from the list. */ public void setRemoveButtonText(String text) { remove.setText(text); } /** * Sets the string that seperates items in the list when the * list is stored as a single String in the preference store. */ public void setSeperator(String seperator) { this.seperator = seperator; } /** * Creates the single String representation of the list * that is stored in the preference store. */ private String createListString(String[] items) { StringBuffer path = new StringBuffer("");//$NON-NLS-1$ for (int i = 0; i < items.length; i++) { path.append(items[i]); path.append(seperator); } return path.toString(); } /** * Parses the single String representation of the list * into an array of list items. */ private String[] parseString(String stringList) { StringTokenizer tokenizer = new StringTokenizer(stringList, seperator); int tokenCount = tokenizer.countTokens(); String[] elements = new String[tokenCount]; for (int i = 0; i < tokenCount; i++) { elements[i] = tokenizer.nextToken(); } return elements; } // Sets the enablement of the remove button depending // on the selection in the list. private void selectionChanged() { int index = list.getSelectionIndex(); remove.setEnabled(index >= 0); } }