在对象的JComboBox实例项 [英] Item in JComboBox instance of an object

问题描述

您好，我有以下code，看是否在JComboBox中的项目是一个类（Persoon）的实例。

Hello I have the following code to see if an item in the JComboBox is instance of a class(Persoon).

    public class ItemChangeListener implements ItemListener {

        Persoon selectedPerson;
        RekeningApp app;
        PersoonView view;

        public ItemChangeListener(PersoonView view) {

            this.view = view;

        }

        public void itemStateChanged(ItemEvent event) {
            if (event.getStateChange() == ItemEvent.SELECTED) {
                Object item = event.getItem();
                System.out.println("Itemchangelistener " + item);
                // do something with object
                if(item instanceof Persoon) {
                    System.out.println("Instance");
                    this.selectedPerson = (Persoon) item;
                    view.setOverzicht(this.selectedPerson);
                } else {
                    this.selectedPerson = null;
                }
            }
        }

    }

项的输出是persoon.name变量的值。所以在JComboBox中的项目实际上是字符串。

The output of item is the value of persoon.name variable. so the items in the JComboBox are actually strings.

这是JComboBox的列表是如何设置的。

this is how the JComboBox list is set.

personenList.addItem（persoon.getNaam（））;

我的问题是..我怎么能检查如果这Persoon对象excists，是一样的，在JComboBox中？

My question is.. how can I check If this Persoon object excists and is the same as in the JComboBox?

推荐答案

您应该添加到的JComboBox 的人对象，不只是名字，所以当你调用对象项目= event.getItem（）; 这将返回人，而不是字符串。如果你想在 JComboBox中显示这个人的名字，覆盖的的toString 方法人类是这样的：

You should add to the JComboBox the Person objects, not just the name, so when you call Object item = event.getItem(); this will return the Person, not an String. If you want to display the person's name in the JComboBox, override the toString method in Person class to something like this:

public String toString()
    return this.naam;
}

和您应添加项目到列表中。

And you should add the items to the list.

personenList.addItem(persoon);   

修改

如果您不希望（或可以）覆盖，你应该使用自定义渲染器的的toString 方法。这是一个链接，例如：

If you don't want (or can) override the toString method you should use a custom renderer. This is a link to and example:

的http://docs.oracle.com/javase/tutorial/uiswing/components/combobox.html#renderer

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