How to use

ArraySelection

in

com.badlogic.gdx.scenes.scene2d.utils

/** Returns the first selected item, or null. */
public T getSelected () {
  return selection.first();
}

  /** Removes objects from the selection that are no longer in the items array. If {@link #getRequired()} is true and there is no
   * selected item, the first item is selected. */
  public void validate () {
    Array<T> array = this.array;
    if (array.size == 0) {
      clear();
      return;
    }
    for (Iterator<T> iter = items().iterator(); iter.hasNext();) {
      T selected = iter.next();
      if (!array.contains(selected, false)) iter.remove();
    }
    if (required && selected.size == 0) set(array.first());
  }
}

public SelectBox (SelectBoxStyle style) {
  setStyle(style);
  setSize(getPrefWidth(), getPrefHeight());
  selection.setActor(this);
  selection.setRequired(true);
  selectBoxList = new SelectBoxList(this);
  addListener(clickListener = new ClickListener() {
    public boolean touchDown (InputEvent event, float x, float y, int pointer, int button) {
      if (pointer == 0 && button != 0) return false;
      if (disabled) return false;
      if (selectBoxList.hasParent())
        hideList();
      else
        showList();
      return true;
    }
  });
}

/** Sets the selection to only the passed item, if it is a possible choice.
 * @param item May be null. */
public void setSelected (T item) {
  if (items.contains(item, false))
    selection.set(item);
  else if (selection.getRequired() && items.size > 0)
    selection.set(items.first());
  else
    selection.clear();
}

/** Sets the selection to only the selected index.
 * @param index -1 to clear the selection. */
public void setSelectedIndex (int index) {
  if (index < -1 || index >= items.size)
    throw new IllegalArgumentException("index must be >= -1 and < " + items.size + ": " + index);
  if (index == -1) {
    selection.clear();
  } else {
    selection.set(items.get(index));
  }
}

/** Sets the selection to only the selected index. */
public void setSelectedIndex (int index) {
  selection.set(items.get(index));
}

switch (keycode) {
case Keys.A:
  if (UIUtils.ctrl() && selection.getMultiple()) {
    selection.clear();
    selection.addAll(items);
    return true;

/** @return The index of the first selected item. The top item has an index of 0. Nothing selected has an index of -1. */
public int getSelectedIndex () {
  ObjectSet<T> selected = selection.items();
  return selected.size == 0 ? -1 : items.indexOf(selected.first(), false);
}

public boolean touchDown (InputEvent event, float x, float y, int pointer, int button) {
  if (pointer != 0 || button != 0) return true;
  if (selection.isDisabled()) return true;
  getStage().setKeyboardFocus(List.this);
  if (items.size == 0) return true;
  int index = getItemIndexAt(y);
  if (index == -1) return true;
  selection.choose(items.get(index));
  touchDown = index;
  return true;
}

private void up() {
  if (parent == null || list.getSelection().size() == 0)
    return;
  Array<Action> sel = new Array<Action>();
  for (Action a : getSortedSelection()) {
    
    int pos = list.getItems().indexOf(a, true);
    if (pos == -1 || pos == 0)
      return;
    Array<Action> items = list.getItems();
    Action e = items.get(pos);
    Action e2 = items.get(pos - 1);
    sel.add(e);
    if (isControlAction(e) && isControlAction(e2)) {
      continue;
    }
    parent.getActions().set(pos - 1, e);
    parent.getActions().set(pos, e2);
    items.set(pos - 1, e);
    items.set(pos, e2);
  }
  list.getSelection().clear();
  list.getSelection().addAll(sel);
  upBtn.setDisabled(list.getSelectedIndex() == 0);
  downBtn.setDisabled(list.getSelectedIndex() == list.getItems().size - 1);
  Ctx.project.setModified();
}

public void clearItems () {
  if (items.size == 0) return;
  items.clear();
  selection.clear();
  invalidateHierarchy();
}

public CustomList(CustomListStyle style, CellRenderer<T> r) {
  selection = new ArraySelection<T>(items);
  selection.setActor(this);
  selection.setRequired(true);
  cellRenderer = r;
  setStyle(style);
  setSize(getPrefWidth(), getPrefHeight());
  addListener(new InputListener() {
    public boolean touchDown(InputEvent event, float x, float y, int pointer, int button) {
      if (pointer == 0 && button != 0)
        return false;
      if (selection.isDisabled())
        return false;
      CustomList.this.touchDown(y);
      return true;
    }
  });
}

List list = new List(skin);
list.setItems(listEntries);
list.getSelection().setMultiple(true);
list.getSelection().setRequired(false);

private void toggleEnabled() {
  if (list.getSelection().size() <= 0)
    return;
  Array<Action> sel = new Array<Action>();
  for (Action a : list.getSelection().toArray()) {
    // CONTROL ACTIONS CAN'T BE DISABLED
    if (a == null || isControlAction(a))
      continue;
    Array<Action> items = list.getItems();
    int pos = items.indexOf(a, true);
    if (a instanceof DisableActionAction) {
      Action a2 = ((DisableActionAction) a).getAction();
      parent.getActions().set(pos, a2);
      items.set(pos, a2);
      sel.add(a2);
    } else {
      DisableActionAction a2 = new DisableActionAction();
      a2.setAction(a);
      parent.getActions().set(pos, a2);
      items.set(pos, a2);
      sel.add(a2);
    }
  }
  Ctx.project.setModified();
  list.getSelection().clear();
  list.getSelection().addAll(sel);
}

public void clicked (InputEvent event, float x, float y) {
  selectBox.selection.choose(list.getSelected());
  hide();
}

@Override
protected void delete() {
  if (list.getSelection().size() == 0)
    return;
    list.getSelection().clear();
  } else if (pos >= list.getItems().size) {
    list.getSelection().choose(list.getItems().get(list.getItems().size - 1));
  } else {
    list.getSelection().choose(list.getItems().get(pos));

objList.getSelection().items().clear();
objList.getSelection().items().add(node.name);
  objList.getSelection().setProgrammaticChangeEvents(false);
  objList.setSelectedIndex(itemIdx);
  objList.getSelection().setProgrammaticChangeEvents(true);
  float itemHeight = objList.getItemHeight();
  focusListScrollPane.setScrollY(itemIdx * itemHeight);

public void addElements(PARENT parent, List<T> elements) {
  this.parent = parent;
  list.getItems().clear();
  list.getSelection().clear();
  if (elements != null) {
    for (T e : elements) {
      addItem(e);
    }
  }
  toolbar.disableEdit(list.getSelectedIndex() < 0);
  if (sorted) {
    list.sortByTitle();
  }
  
  if (getItems().size > 0)
    list.getSelection().choose(list.getItems().get(0));
  toolbar.disableCreate(parent == null);
  // container.prefHeight(list.getItemHeight() * (list.getItems().size >
  // 3?list.getItems().size:3));
  list.invalidateHierarchy();
}

list.getSelection().clear();
list.getSelection().addAll(sel);
Ctx.project.setModified();

if (cullingArea == null || (itemY - itemHeight <= cullingArea.y + cullingArea.height && itemY >= cullingArea.y)) {
  T item = items.get(i);
  boolean selected = selection.contains(item);
  if (selected) {
    Drawable drawable = selectedDrawable;