Java swing下拉选择监听器

Question

我有一个 JCombobox，其中包含大量项目。选择一个项目后，我需要完成一些事情。我尝试使用 actionListener 和 itemListner

myComboBox.addItemListener(new ItemListener(){
        @Override
        public void itemStateChanged(ItemEvent e) {
        if (e.getStateChange() == ItemEvent.SELECTED) {
            String selection = (String)myComboBox.getSelectedItem();
            System.out.println("Selected: "+selection ) ;
        }
    }
});

使用 Action 监听器，我尝试了同样的事情

我面临的问题是这样的当用户滚动打开的下拉菜单时，他会无意中继续选择他不需要的每个项目。 (或者如果使用鼠标滚轮等...)。
因此，我希望能够仅捕获用户所做的选择。如何做呢 ？

Answer 1

The problem, I am facing is this When user rolls through the open drop down he inadvertently keep selecting each item he does not need.

您可以使用以下方法阻止监听器触发:

comboBox.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE);

例如:

/*
    This works on non editable combo boxes
*/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.plaf.basic.*;
import javax.swing.text.*;

public class ComboBoxAction extends JFrame implements ActionListener
{
    public ComboBoxAction()
    {
        JComboBox<String> comboBox = new JComboBox<String>();
        comboBox.addActionListener( this );

        comboBox.addItem( "Item 1" );
        comboBox.addItem( "Item 2" );
        comboBox.addItem( "Item 3" );
        comboBox.addItem( "Item 4" );

        //  This prevents action events from being fired when the
        //  up/down arrow keys are used on the dropdown menu

        comboBox.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE);

        getContentPane().add( comboBox );
        getContentPane().add( new JTextField(), BorderLayout.SOUTH );
    }

    public void actionPerformed(ActionEvent e)
    {
        System.out.println( e.getModifiers() );

        JComboBox comboBox = (JComboBox)e.getSource();
        System.out.println( comboBox.getSelectedItem() );

        //  make sure popup is closed when 'isTableCellEditor' is used

//      comboBox.hidePopup();
    }

    public static void main(String[] args)
    {
        ComboBoxAction frame = new ComboBoxAction();
        frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
        frame.pack();
        frame.setVisible( true );
     }
}