在GUI中列出ArrayList中的对象并在许多ArrayList之间交替 [英] Listing objects in ArrayList in GUI and alternating between many ArrayLists

问题描述

我当前正在处理一个个人项目，在这个项目中，要求用户创建3个不同类别的对象，因此在创建对象之后，有一种方法可以检查对象的类别，然后添加它到一个ArrayList. 更多详细信息:该对象称为车辆"，分为三类:两个轮子，三个轮胎，三个轮子.因此，当您创建新的Vehicle时，将要求您指定要创建的车辆类型，比如说两个轮子，将调用一个方法，该方法会将对象添加到ArrayList twoWheelList中，依此类推. /p>

此刻我有两个问题，我正在为此程序制作一个GUI，我想在其中显示存储在ArrayLists中的信息，基本上，用户有一个comboBox，其下面有三个类别的名称.它.我希望当用户选择"Two Wheels"时，一个jList将列出ArrayList twoWheelList

中的每个对象

我该如何实现?我已经尝试了好几次，但运气不好.我正在使用NetBeans，我不太了解整个JFrame概念以及如何编写源代码，对于第一个问题，我需要程序知道用户选择了什么，我应该只使用IF语句吗? ? 如何使对象的ArrayList显示在jList中?

解决方案

首先将ItemListener添加到JComboBox.在itemStateChanged事件中，您将要监视ItemEvent或SELECTED状态.

从JComboBox获取选择的值.这可能需要您提供某种外观，以便将组合框中的项目与ArrayList关联，或者，如我所愿，将包含该项目名称的包装器类和ArrayList打包为单个对象，它将提供获取ArrayList

的方法

然后使用自定义的ListModel，您可以将ArrayList包装在其中，并将其应用于屏幕上的JList ...

public class ProxyListModel extends AbstractListModel<Vehicle> {

    private List<Vehicle> vehicles;

    public ProxyListModel(List<Vehicle> vehicles) {
        // It might be better to simply make a copy of the list
        // but that's up to you...
        this.vehicles = vehicles;
    }

    @Override
    public int getSize() {
        return vehicles.size();
    }

    @Override
    public Vehicle getElementAt(int index) {
        return vehicles.get(index);
    }

}

查看如何使用组合框和如何使用列表.密切注意有关自定义渲染的讨论.

I'm currently working on a personal project, in this project, the user is asked to create objects under 3 different categories, so after the object is created, there's a method that check's the category of the object and then it adds it to an ArrayList. More Details: the object is called Vehicle, there're three categories: Two wheels, three weels, three wheels. So, when you create a new Vehicle, you'd be asked to specify what kind of vehicles you're creating, say you said two wheels, a method will be called which will add the object into ArrayList twoWheelList, and so on.

I have two problems at the moment, I'm making a GUI for this program, where I'd like to display information stored in the ArrayLists, basically the user has a comboBox, which has the name of the three categories underneath it. I'd like that when the user chooses let's say "Two Wheels", a jList will list each object in the ArrayList twoWheelList

How can I make that happen? I've tried several times but I'm coming out with no luck. I'm using NetBeans, I don't really understand the whole JFrame concept and how to write the source codes, for the first problem where I'd need the program to know what did the user choose, should I just use an IF statement? How can I make the ArrayList of objects to be displayed in the jList?

解决方案

Start by adding an ItemListener to the JComboBox. In the itemStateChanged event, you will want to monitor the ItemEvent or the SELECTED state.

Get the selected value from the JComboBox. This may require you to provide some kind of look that can associate the item in the combo box with the ArrayList or, as I would prefer, a wrapper class which contained the name of the item an the ArrayList wrapped into a single object, which would provide the means to obtain the ArrayList

Then using a custom ListModel, you can wrap the ArrayList within it and apply it to the JList you have on the screen...

public class ProxyListModel extends AbstractListModel<Vehicle> {

    private List<Vehicle> vehicles;

    public ProxyListModel(List<Vehicle> vehicles) {
        // It might be better to simply make a copy of the list
        // but that's up to you...
        this.vehicles = vehicles;
    }

    @Override
    public int getSize() {
        return vehicles.size();
    }

    @Override
    public Vehicle getElementAt(int index) {
        return vehicles.get(index);
    }

}

Check out How to Use Combo Boxes and How to Use Lists for more details. Play close attention to the discussions about custom rendering.

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