如何在JFrame中调整JScrollPane的大小?以及如何从Java文件中读取内容? [英] How do I resize a JScrollPane within a JFrame? And how do I read from a file in Java?

问题描述

我有一个歌曲库，并且我希望此选择列表仅位于窗口的左侧，因为我想将有关歌曲的其他信息放在右侧.我不确定如何更改JFrame内部的JScrollPane的大小.

I have a song library, and I would like this selection list to only be on the left hand side of the window because I want to put other information about the song on the righthand side. I'm not sure how to change the size of JScrollPane, which is inside the JFrame.

在此库中，我希望能够将文件中存储的歌曲导入到我的歌曲库中.现在，我的代码中有一个数组，但是我希望能够从文本文件中读取而不是使用这种方法.在文件中，我希望能够存储有关歌曲的艺术家和专辑信息，但我不希望它显示在歌曲列表中.

In this library, I want to be able to import the songs stored in a file to my song library. Right now, I have an array within my code, but I want to be able to read from a text file instead of using this approach. In the file, I want to be able to store artist and album information about the song, but I don't want it to display in the song list.

    String songs[] = {"Song1", "Song2", "Song3", "Song4", "Song5"};
    JList list = new JList(songs);

    public SongLib(){

        JFrame songLibrary = new JFrame("Song Library");
        songLibrary.setLocationRelativeTo(null);
        songLibrary.setResizable(true);
        songLibrary.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

        list.addListSelectionListener(new ListSelectionListener(){
            public void valueChanged(ListSelectionEvent evt){
                int i = list.getSelectedIndex();
                if (i != -1)
                    System.out.println("Selected: " + songs[i]);
                else
                    System.out.println("Choose a song");    
            }
        });

        JScrollPane JSPane = new JScrollPane(list);
        JSPane.setPreferredSize(new Dimension(100,100));
        songLibrary.add(JSPane);
        songLibrary.setSize(400,400);
        songLibrary.setVisible(true);
    }

    public static void main(String[] args){
        new SongLib();
    }

推荐答案

1. (在您的整个余生中)停止通话setPreferredSize().这意味着此调用:JSPane.setPreferredSize(new Dimension(100,100));应该绝对被删除.
2. 如果要并排放置两个带有可拖动分隔符的面板，请使用JSplitPane.如果您不希望使用可拖动的分隔线，请使用带有适当LayoutManager的JPanel(GridBagLayout可能是一个不错的选择)
3. 从文件读取非常容易，只需在SO上进行搜索，您就会发现数百个响应.如果您想解析csv文件，则周围有一些库可以帮助您做到这一点.最终，如果您考虑让它成为一种应用程序，那么有些小型的纯Java可嵌入数据库将比简单的文本文件在读取/存储/搜索信息方面做得更好.
4. 学习并遵循Java命名约定:变量始终以小写字母开头.

1. Stop calling (for the rest of your entire life) setPreferredSize(). Meaning that this call: JSPane.setPreferredSize(new Dimension(100,100)); should definitely be removed.
2. If you want to have 2 panels side-by-side with a draggable separator: use JSplitPane. If you don't want the draggable divider, use a JPanel with an appropriate LayoutManager (GridBagLayout may be a good choice)
3. Reading from a file is pretty easy, just make a search on SO and you will find hundreds of response. If you want to parse csv-files, there are some libraries around that can help you do that. Eventually, if you consider making this an application for a while, there are some small pure-java, embeddable, databases which will do a much better job at reading/storing/searching information than a simple text-file.
4. Learn the Java naming conventions and stick to them: variables always start with a lower-case letter.

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