java - JComboBox ，如何知道一次选择了哪个特定选项

Question

您好，我目前正在尝试为我的大学作业设计一个购物车，我目前正在尝试做的是有一个组合框，当用户单击组合框中的一个选项时，会显示有关用户选择的选项的信息。

我花了一段时间试图查找如何执行此操作，给出的建议是在组合框上使用 actionListener。我已经添加了一个 actionListerner 但是我有点卡在下一部分。目前，当用户第一次点击一个选项时，它会正确显示文本，但是如果他在之后选择另一个选项，文本将保持不变。我需要找到一种方法来继续运行我的 IF 语句以继续检查已选择的内容。我尝试向我的 ActionListener 添加一个 while 循环，但这似乎没有用。

下面是来自监听器的代码以及我如何创建组合框及其选项。

组合框

golfBagOptions = new JComboBox();

      golfBagOptions.addItem("TaylorMade Juggernaut Cart Bag");
      golfBagOptions.addItem("Mizuno Golf Rider Cart Bag");
      golfBagOptions.addItem("Titleist RC13 Reverse Cart Bag");
      golfBagOptions.addItem("Callaway Golf Euro Chev Org Cart Bag");

Action 监听器

golfBagOptions.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){

            if (golfBagOptions.getSelectedItem().toString()=="TaylorMade Juggernaut Cart Bag");{
                String startNewLine = System.getProperty("line.separator");
                golfBagInformation.setText("Name : TaylorMade Juggernaut Cart Bag" + startNewLine + "Price: £129" + startNewLine + "Colour: Blue" + startNewLine + 
                        "Description: With powerful looks and crush-resistant construction, the TaylorMade Juggernaut Cart Bag is an intimidating and widely popular golf bag." );
            }
            if (golfBagOptions.getSelectedItem().toString()=="Mizuno Golf Rider Cart Bag");{
                String startNewLine = System.getProperty("line.separator");
                golfBagInformation.setText("Name : Mizuno Golf Rider Cart Bag" + startNewLine + "Price: £99.99" + startNewLine + "Colour: Black" + startNewLine + 
                        "Description: Something which is often difficult to achieve on a busy golf course is that sense of everything in its place. The Mizuno Aerolite 5 Golf Stand Bag has been created with an abundance of storage options, " +
                        "excellent golf club placement and " +
                        "reduces strain on the back when carried." );
            }
            if (golfBagOptions.getSelectedItem().toString()=="Titleist Lightweight SE Stand Bag");{
                String startNewLine = System.getProperty("line.separator");
                golfBagInformation.setText("Name : TaylorMade Juggernaut Cart Bag" + startNewLine + "Price: £99.99" + startNewLine + "Colour: Silver" + startNewLine + 
                        "Description: Carry your golf gear around the golf course effortlessly with the stylish Titleist Lightweight SE Stand Bag. Slip on this comfortable bag and you will be amazed by the " +
                        "lightweight comfort and convenience of a fast stand mechanism with broad foot and tripod rubber feet for ultimate stability." +
                        " The Titleist Lightweight SE Stand Bag is perfect for walking around the course in style." );
            }
            if (golfBagOptions.getSelectedItem().toString()=="Cleveland Golf Lightweight Stand Bag");{
                String startNewLine = System.getProperty("line.separator");
                golfBagInformation.setText("Name : TaylorMade Juggernaut Cart Bag" + startNewLine + "Price: £79.99" + startNewLine + "Colour: Blue" + startNewLine + 
                        "Description: To keep your golf clubs protected both on and off the golf course, the Cleveland Lightweight Stand Bag will assure total comfort, safety and smart construction." );
            }

        }
    });

如果有人能给我指出正确的方向，我将不胜感激。

干杯

Answer 1

改变

  if (golfBagOptions.getSelectedItem().toString()=="TaylorMade Juggernaut Cart Bag");{

到

 if (((String)golfBagOptions.getSelectedItem()).equals("TaylorMade Juggernaut Cart Bag"){

调整所有 if 条件的变化。

1 ) Remove all the semicolon from the if statements

2 ) To compare String objects in java use .equals() method instead of "=="operator