Java tutorial
/* * Copyright 2016 Albert Tregnaghi * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions * and limitations under the License. * */ package de.jcup.egradle.eclipse.preferences; import org.eclipse.core.runtime.Assert; 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.widgets.Combo; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Control; /** * A field editor for a combo box that allows the drop-down selection of one of * a list of items. * * @since 3.3 */ public class ChangeableComboFieldEditor extends FieldEditor { /** * The <code>Combo</code> widget. */ private Combo fCombo; /** * The value (not the name) of the currently selected item in the Combo widget. */ private String fValue; /** * The names (labels) and underlying values to populate the combo widget. These should be * arranged as: { {name1, value1}, {name2, value2}, ...} */ private String[][] fEntryNamesAndValues; /** * Create the combo box field editor. * * @param name the name of the preference this field editor works on * @param labelText the label text of the field editor * @param entryNamesAndValues the names (labels) and underlying values to populate the combo widget. These should be * arranged as: { {name1, value1}, {name2, value2}, ...} * @param parent the parent composite */ public ChangeableComboFieldEditor(String name, String labelText, String[][] entryNamesAndValues, Composite parent) { init(name, labelText); Assert.isTrue(checkArray(entryNamesAndValues)); fEntryNamesAndValues = entryNamesAndValues; createControl(parent); } /** * Checks whether given <code>String[][]</code> is of "type" * <code>String[][2]</code>. * * @return <code>true</code> if it is ok, and <code>false</code> otherwise */ private boolean checkArray(String[][] table) { if (table == null) { return false; } for (int i = 0; i < table.length; i++) { String[] array = table[i]; if (array == null || array.length != 2) { return false; } } return true; } @Override protected void adjustForNumColumns(int numColumns) { if (numColumns > 1) { Control control = getLabelControl(); int left = numColumns; if (control != null) { ((GridData) control.getLayoutData()).horizontalSpan = 1; left = left - 1; } ((GridData) fCombo.getLayoutData()).horizontalSpan = left; } else { Control control = getLabelControl(); if (control != null) { ((GridData) control.getLayoutData()).horizontalSpan = 1; } ((GridData) fCombo.getLayoutData()).horizontalSpan = 1; } } @Override protected void doFillIntoGrid(Composite parent, int numColumns) { int comboC = 1; if (numColumns > 1) { comboC = numColumns - 1; } Control control = getLabelControl(parent); GridData gd = new GridData(); gd.horizontalSpan = 1; control.setLayoutData(gd); control = getComboBoxControl(parent); gd = new GridData(); gd.horizontalSpan = comboC; gd.horizontalAlignment = GridData.FILL; control.setLayoutData(gd); control.setFont(parent.getFont()); } @Override protected void doLoad() { updateComboForValue(getPreferenceStore().getString(getPreferenceName())); } @Override protected void doLoadDefault() { updateComboForValue(getPreferenceStore().getDefaultString(getPreferenceName())); } @Override protected void doStore() { if (fValue == null) { getPreferenceStore().setToDefault(getPreferenceName()); return; } getPreferenceStore().setValue(getPreferenceName(), fValue); } @Override public int getNumberOfControls() { return 2; } public Combo getComboBoxControl(Composite parent) { if (fCombo == null) { fCombo = new Combo(parent, SWT.READ_ONLY); fCombo.setFont(parent.getFont()); for (int i = 0; i < fEntryNamesAndValues.length; i++) { fCombo.add(fEntryNamesAndValues[i][0], i); } fCombo.addSelectionListener(new SelectionAdapter() { @Override public void widgetSelected(SelectionEvent evt) { String oldValue = fValue; String name = fCombo.getText(); fValue = getValueForName(name); setPresentsDefaultValue(false); fireValueChanged(VALUE, oldValue, fValue); } }); } return fCombo; } /* * Given the name (label) of an entry, return the corresponding value. */ private String getValueForName(String name) { for (int i = 0; i < fEntryNamesAndValues.length; i++) { String[] entry = fEntryNamesAndValues[i]; if (name.equals(entry[0])) { return entry[1]; } } return fEntryNamesAndValues[0][0]; } /* * Set the name in the combo widget to match the specified value. */ private void updateComboForValue(String value) { fValue = value; for (int i = 0; i < fEntryNamesAndValues.length; i++) { if (value.equals(fEntryNamesAndValues[i][1])) { fCombo.setText(fEntryNamesAndValues[i][0]); return; } } if (fEntryNamesAndValues.length > 0) { fValue = fEntryNamesAndValues[0][1]; fCombo.setText(fEntryNamesAndValues[0][0]); } } @Override public void setEnabled(boolean enabled, Composite parent) { super.setEnabled(enabled, parent); getComboBoxControl(parent).setEnabled(enabled); } /** * Returns the value of the current selected entry (not the label) * @return value */ public String getStringValue() { return fValue; } /** * Returns label of current selected entry * @return value */ public String getLabel() { return getValueForName(fValue); } /** * Set the value (not the label) of wanted new current value * @param value */ public void setStringValue(String value) { updateComboForValue(value); } }