java - JPanel is not updating one of the two pieces of data I need to be updated -

i trying track of supplies stored in knapsack object , create interface shows supplies update using observer/observable implementation. reason when run code, 2 items in knapsack, second item updates , shows expiration date decreasing time change triggered. first 1 not change @ all, if it's static label. please let me know did wrong? in advance! also, i'm super new java programming please information/explanation appreciated.

here code:

package view;  import java.util.observable;  import java.util.observer;  import javax.swing.jlabel;  import javax.swing.jpanel;  import javax.swing.swingutilities;    import supplies.supplies;  import model.adventure;  import model.knapsack;    public class inventoryview extends jpanel implements observer{  	private knapsack knapsack;  	private adventure adventure;  	private jlabel b;    	public inventoryview(adventure adventure) {  		this.adventure=adventure;  		this.knapsack=adventure.getsquad().getknapsack();  		for (supplies supply : knapsack.getsupplies()) {  			b=new jlabel(supply.tostring());  			add(b);  		}  		knapsack.addobserver(this);  	}  	@override  	public void update(observable arg0, object arg1) {  		swingutilities.invokelater(new runnable() {  			public void run() {  				for (supplies supply : knapsack.getsupplies()) {  					b.settext(supply.tostring());  					add(b);  				}				  			}  		});  	}  }

swing lazy when comes container updates (add/removes), allows execute number of add/removes in quick succession without fear system grind halt while attempts update entire container hierarchy on each call.

call revalidate , repaint after have added components. also, make sure jpanel using layout manager capable of supporting multiple children.

you might consider using jlist or jtable instead