Question: I have a JPanel with many objects, and one main action that can be performed: a calculation. There is a button to do this, but also a JTextField and other components in which the user might want to press enter in. For example, if you are selecting something from a JComboBox and press enter, the calculation will happen. Is there an easy way to add such a listener to all the contents from a JPanel, instead of adding actionListeners to every single component?

Answer: 
`JPanel` extends `JComponent`, that inherits `Container`. You can use `getComponents()`. You get a `Component[]` array, which you can loop through and add for each component, that is a subclass of `Component` like `Button`, and add the same `ActionListener` for each component. See <http://docs.oracle.com/javase/6/docs/api/java/awt/Component.html>
thats what i did right now and it worked

```
private void setActionListeners() {
        for (Component c : this.getComponents()){
            if (c.getClass() == JMenuItem.class){
                JMenuItem mi = (JMenuItem) c;
                mi.addActionListener(this);
            }
            if (c.getClass() == JCheckBoxMenuItem.class){
                JCheckBoxMenuItem cmi = (JCheckBoxMenuItem) c;
                cmi.addActionListener(this);
            }
        }
    }

```