ItemStateChanged被两次调用到JComboBox中

Question

Hello and i am using one Combobox and when i triggered IteamStateChage event then that action called twice. but if i called twice i can not make make it possible what i want to do.

So is there any way to called IteamStatechange evet only once. when i change iteam into the Jcombobox. i just need once action of itemStatechange. and using Item State change only.![Here Screen Shot for same.][1]

please help me for same. and thank you for you ans in advance.

Answer 1

In this context, this is expected behaviour. The combobox is signaling the deselection of the current item and the selection of the new item.

In the itemStateChanged method, you need to inspect the state of the ItemEvent to determine what you should do.

public void itemStateChanged(ItemEvent evt) {

    switch (evt.getStateChanged()) {
        case ItemEvent.DESELECTED:
            // Do what ever you want when the item is deselected
            break;
        case ItemEvent.SELECTED:
            // Do what ever you want when the item is selected
            break;
    }
}

Answer 2

Here is an example how to determin if the change event is Select or Deselect:

JComboBox<String> comboBox = new JComboBox<>(new String[] {"one", "two", "foo"});
 comboBox.addItemListener(new ItemListener() {
     @Override
     public void itemStateChanged(ItemEvent e) {
         System.out.println("Change");
         if(e.getStateChange() == ItemEvent.SELECTED){
             System.out.println("Selected");
         }
         if(e.getStateChange() == ItemEvent.DESELECTED){
             System.out.println("Deselected");
         } 
     }
 });