Added multiple selection capability to the component list

src/main/java/envoy/client/ui/list/ComponentList.java

@@ -3,6 +3,8 @@ package envoy.client.ui.list;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
 import java.awt.event.MouseListener;
+import java.util.ArrayList;
+import java.util.List;
 
 import javax.swing.*;
 
@@ -23,8 +25,9 @@ public class ComponentList<E> extends JPanel {
 
 	private ComponentListModel<E>			model;
 	private ComponentListCellRenderer<E>	renderer;
+	private boolean							multipleSelectionEnabled	= false;
 
-	private int currentSelection = -1;
+	private List<Integer> currentSelections = new ArrayList<>();
 
 	private static final long serialVersionUID = 1759644503942876737L;
 
@@ -137,27 +140,38 @@ public class ComponentList<E> extends JPanel {
 	 * @since Envoy v0.1-beta
 	 */
 	private void componentSelected(int index) {
-		if (index == currentSelection) {
+		// removing selection of element at index
+		if (currentSelections.contains(index)) {
 
 			// Clear selection
-			update(currentSelection, false);
+			updateSelection(index, false);
-			currentSelection = -1;
+			currentSelections.remove(Integer.valueOf(index));
 		} else {
 
-			// Remove old selection
+			// Remove old selection if multipleSelection is disabled
-			if (currentSelection >= 0) update(currentSelection, false);
+			if (!multipleSelectionEnabled && currentSelections.size() > 0) clearSelections();
 
 			// Assign new selection
-			currentSelection = index;
+			currentSelections.add(index);
 
 			// Update current selection
-			update(currentSelection, true);
+			updateSelection(index, true);
 		}
 
 		revalidate();
 		repaint();
 	}
 
+	/**
+	 * Clears all currently active selections.
+	 *
+	 * @since Envoy v0.1-beta
+	 */
+	private void clearSelections() {
+		currentSelections.forEach(index2 -> updateSelection(index2, false));
+		currentSelections.clear();
+	}
+
 	/**
 	 * Replaces a list element with a newly rendered instance of its contents.
 	 *
@@ -165,8 +179,43 @@ public class ComponentList<E> extends JPanel {
 	 * @param isSelected the selection state passed to the {@link ListCellRenderer}
 	 * @since Envoy v0.1-beta
 	 */
-	private void update(int index, boolean isSelected) {
+	private void updateSelection(int index, boolean isSelected) {
 		remove(index);
 		add(model.get(index), index, isSelected);
 	}
+
+	/**
+	 * @return the selected elements or null if none is selected
+	 * @since Envoy v0.1-beta
+	 */
+	public List<E> getSelected() {
+		List<E> selected = new ArrayList<>();
+		currentSelections.forEach(index -> selected.add(model.get(index)));
+		return selected;
+	}
+
+	/**
+	 * @return the multipleSelectionEnabled
+	 * @since Envoy v0.1-beta
+	 */
+	public boolean isMultipleSelectionEnabled() { return multipleSelectionEnabled; }
+
+	/**
+	 * Enables the selection of multiple elements.
+	 *
+	 * @see ComponentList#disableMultipleSelection
+	 * @since Envoy v0.1-beta
+	 */
+	public void enableMultipleSelection() { this.multipleSelectionEnabled = true; }
+
+	/**
+	 * Allows only one element to be selected. True by default.
+	 *
+	 * @see ComponentList#enableMultipleSelection
+	 * @since Envoy v0.1-beta
+	 */
+	public void disableMultipleSelection() {
+		this.multipleSelectionEnabled = false;
+		clearSelections();
+	}
 }