How to enable a JButton on a condition?

Question

I'm trying to create a JButton that enables when certain conditions are met. The program sets setEnabled(false) as initial value, but after an update, it should be setEnabled(true).

I tried several things. Here some code:

public class SwimAction extends AbstractAction {
    private final PoolModel poolModel;
    private final Swimmer swimmer;

    public SwimAction(PoolModel poolModel, Swimmer swimmer) {
        super("GO!");
        this.poolModel = poolModel;
        this.swimmer = swimmer;
        // default
        setEnabled(false);
    }

I tried the following:

// Replaced the setEnabled(false) by setEnabled(checkGo())
public boolean checkGo(){
        return(pool.isNotOccupied());
    }

// Overwrite setEnabled
@Overwrite
public void setEnabled(boolean bool){
        boolean oldBool = this.enabled;
        if (oldBool != bool && pool.isNotOccupied()) {
            this.enabled = bool;
            this.firePropertyChange("enabled", oldBool, bool);
        }
    }

However, none of them worked. Anyone knows how to enable the button when a certain condition (pool.isNotOccupied()) is met?

Answer 1

Seems like you need to listener for a change in the state of the pool object's occupied property, and the best way to do this is to give it a listener of some sort. This could be as simple as a ChangeListener or perhaps better, a PropertyChangeListener. The details of the best solution would likely depend much on the structure of your program, of the rest of the code that we can't see, but, if PoolModel is what you're listening to, what if you gave it...

public class PoolModel {
    public static final String OCCUPIED = "occupied";
    private PropertyChangeSupport propChangeSupport = new PropertyChangeSupport(this);
    private boolean occupied;
    
    public void addPropertyChangeListener(PropertyChangeListener l) {
        propChangeSupport.addPropertyChangeListener(l);
    }
    
    // also have a remove listener
    
    public boolean isOccupied() {
        return occupied;
    }
    
    public void setOccupied(boolean occupied) {
        boolean oldValue = this.occupied;
        boolean newValue = occupied;
        this.occupied = occupied;
        propChangeSupport.firePropertyChange(OCCUPIED, oldValue, newValue);
    }
    
    // ......
    
    

And then in the code that uses it:

poolModel.addPropertyChangeListener(pcEvent -> {
    if (pcEvent.getPropertyName().equals(OCCUPIED)) {
        setEnabled((boolean) pcEvent.getNewValue());
    }
});