Classe pronta pra selecionar

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Rectangle2D;
import java.util.Vector;

import javax.swing.*;

@SuppressWarnings("serial")
public class JKSSelect extends JComponent{
	
	private Point point;
	@SuppressWarnings("unused")
	private JComponent component;
	private Vector <Selectable> unselected;
	private Vector <Selectable> selected;
	
	@SuppressWarnings("unchecked")
	public JKSSelect(JComponent component, Vector <? extends Selectable> selection){
		
		super();
		this.component = component;
		this.unselected = (Vector<Selectable>) selection;
		this.selected = new Vector <Selectable> ();
		this.containerAction(component);
		point = new Point();
		this.setBorder(BorderFactory.createTitledBorder(""));
		component.addContainerListener(new ContainerAdapter(){
			@Override
			public void componentAdded(ContainerEvent e) {
				if(e.getChild() instanceof Selectable){
					e.getChild().addMouseListener(new JKSClick());
				}
			}
		});
		
	}
	
	private void makeSquare(Point a, Point b){
		Point aux;
		if(a == null || b == null){
			a = new Point(0,0);
			b = new Point(0,0);
		}
		if(a.x == 0 && a.y == 0 && b.x == 0 && b.y == 0){
			this.setLocation(0,0);
            this.setSize(0,0);
		}
		if((a.x>=b.x && a.y>b.y) || (a.x<b.x && a.y>=b.y)){
			aux = a;
			a = b;
			b = aux;
		}
		if(a.x<=b.x && a.y<b.y){
			this.setLocation((int) (a.x),(int) (a.y));
            this.setSize((int) (b.x-a.x),(int) (b.y-a.y));
		}else if(a.x>b.x && a.y<=b.y){
			this.setLocation((int) (b.x),(int) (a.y));
            this.setSize((int) (a.x-b.x),(int) (b.y-a.y));
		}	
	}
	
	public void containerAction(JComponent container){
		container.addMouseListener(new MouseAdapter(){
			@Override
			public void mouseClicked(MouseEvent arg0) {
				unselectAll();
				
			}

			@Override
			public void mousePressed(MouseEvent arg0) {
				if(!arg0.isControlDown()) unselectAll();
				point = arg0.getPoint();
				setVisible(true);
			}

			@Override
			public void mouseReleased(MouseEvent arg0) {
				setVisible(false);
				for(int x = 0; x < unselected.size(); x++){
					if((new Rectangle2D.Double(getLocation().getX(),getLocation().getY(),getSize().getWidth(),getSize().getHeight())).contains(unselected.get(x).getLocation())){
						unselected.get(x).setSelected(true);
						selected.add(unselected.remove(x));
						x--;
					}	
				}
				makeSquare(new Point(0,0), new Point(0,0));
			}
		});
		
		container.addMouseMotionListener(new MouseMotionAdapter(){
			@Override
			public void mouseDragged(MouseEvent arg0) {
				makeSquare(point, arg0.getPoint());	
			}
		});
		
		
	}
	
	public void unselectAll() {
		while(selected.size() != 0){
			selected.get(0).setSelected(false);
			unselected.add(selected.remove(0));
		}
	}
	
	public void selectAll() {
		while(unselected.size() != 0){
			unselected.get(0).setSelected(true);
			selected.add(unselected.remove(0));
		}
	}

	public Vector <? extends Selectable> getSelectedArray(){
		return this.selected;
	}
	
	public Vector <? extends Selectable> getUnselectedArray(){
		return this.unselected;
	}
	
	class JKSClick extends MouseAdapter{
		@Override
		public void mouseClicked(MouseEvent e) {
			System.out.printf("Clicado");
			if(!e.isControlDown())unselectAll();
			if(selected.remove((Selectable)e.getComponent())){
				unselected.add((Selectable)e.getComponent());
				((Selectable)e.getComponent()).setSelected(false);
			}else if(unselected.remove((Selectable)e.getComponent())){
				selected.add((Selectable)e.getComponent());
				((Selectable)e.getComponent()).setSelected(true);
			}
						
		}
	}
}

import javax.accessibility.AccessibleComponent;

public interface Selectable extends AccessibleComponent{
	public void setSelected(boolean selected);
	public boolean isSelected();
}

select = new JKSSelect(panel,panel.getSelectableItens());
panel.add(select);