Java JComboBox监听更改选择事件

Question

我正在尝试在Java JComboBox中听取选择的更改.我曾尝试使用ActionListener,但问题是:动作侦听器执行类似这样的操作

public void actionPerformed(ActionEvent e){
    JComboBox<String> source = ((JComboBox<String>)e.getSource());
    String selected = source.getItemAt(source.getSelectedIndex());

    /*now I compare if the selected string is equal to some others 
      and in a couple of cases I have to add elements to the combo*/
}

您可以注意到,当我需要向组合添加元素时,另一个事件被触发并且再次调用actionPerformed方法,即使我不想要它,并且代码可能循环... :(有没有办法到只听选择更改而不是一般的更改事件？谢谢

Answer 1

您可以尝试ItemListener接口的itemStateChanged()方法:

class ItemChangeListener implements ItemListener{
    @Override
    public void itemStateChanged(ItemEvent event) {
       if (event.getStateChange() == ItemEvent.SELECTED) {
          Object item = event.getItem();
          // do something with object
       }
    }       
}

并将监听器添加到您的JComboBox:

source.addItemListener(new ItemChangeListener());