如何与另一个交换 JComboBox 项目？

Question

我正在尝试制作一个货币转换器程序，我希望将 JComboBox 项目从其他 JComboBox when I hit the convert button.替换掉

我知道错误是尝试将字符串转换为整数，但我看不到设置 JComboBox 内容的其他方法。

A screenshot from NetBeans with my results in case the code is hard to understand.

下面是jButton的代码：

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
                try {
              for(int a = 0; a < 4; a++){
                String box2 = (currency2.getItemAt(a));
            System.out.println("List items b4 conversion, JComboBox1: "+ currency1.getItemAt(a));
            System.out.println("List items b4 conversion, JComboBox2: "+ box2+"\n");
            System.out.println("--End of first 2 items--");
System.out.println("JComboBox2 after conv" +currency1.getItemAt(Integer.parseInt(box2)));
                }

                    }catch (NumberFormatException e){
                        System.out.println("error");
                }    
    }

这是打印的内容：

List items b4 conversion, JComboBox1: EUR
List items b4 conversion, JComboBox2: ALL

--End of first 2 items--
error

同时，当我删除：System.out.println("JComboBox2 after conv" +currency1.getItemAt(Integer.parseInt(box2))) 时，它会按预期打印 2 个 JComboBoxes 的所有项目。

Answer 1

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
    String txt1 = (String) JComboBox1.getSelectedItem();
    String txt2 = (String) JComboBox2.getSelectedItem();
    jComboBox1.setSelectedItem(txt2);
    jComboBox2.setSelectedItem(txt1);
}