【发布时间】：2014-01-29 18:24:29
【问题描述】：
一旦用户选择“点击这里上传”按钮，文件路径将被存储到一个文件中，这些路径被读入一个数组列表，显示在 JPanel 上。问题是一旦选择了一个文件，它就永远不会在 JPanel 上自动更新，除非在显示最新信息之前重新运行应用程序。如何纠正这个问题，因为我不知道我哪里出错了。顺便说一下，arraylists 会在运行时更新，但 JPanel 永远不会更新。
public class Media2 extends JPanel {
private JPanel video_pnl, control_pnl;
private JButton play_btn;
private JLabel loc_lbl;
private int increment;
ArrayList<String> file_location;
ArrayList<JButton> button_lists;
private FileWriter file_writer;
private BufferedWriter buffered_writer;
private JFileChooser filechooser;
private File file;
private JButton btn_upload;
private BufferedReader br;
private FileReader fr;
public Media2(ArrayList<String> file_location) throws IOException {
btn_upload = new JButton("Click here to Upload Video");
String file_path = "C:\\Users\\goldAnthony\\Documents\\NetBeansProjects\\VDMS\\src\\VideoInfos.txt";
file = new File(file_path);
if (!file.exists()) {
file.createNewFile();
file_writer = new FileWriter(file.getAbsolutePath());
} else {
file_writer = new FileWriter(file.getAbsolutePath(), true);
}
add(btn_upload);
Handlers handler = new Handlers();
btn_upload.addActionListener(handler);
this.file_location = file_location;
readFile(file_location, file_path);
}
private void readFile(ArrayList<String> file_location, String file_path) throws FileNotFoundException, IOException {
fr = new FileReader(file_path);
br = new BufferedReader(fr);
String text = "";
String line2;
line2 = br.readLine();
while (line2 != null) {
int i = 0;
file_location.add(i, line2);
line2 = br.readLine();
i++;
}
configurePanel(file_location);
//System.out.print(file_location.size() + "in the read file 1");
}
private void configurePanel(ArrayList<String> file_location) {
increment = 0;
while (increment < file_location.size()) {
video_pnl = new JPanel();
video_pnl.setLayout(new BoxLayout(video_pnl, BoxLayout.Y_AXIS));
loc_lbl = new JLabel();
loc_lbl.setText(file_location.get(increment));
control_pnl = new JPanel();
control_pnl.setLayout(new FlowLayout(FlowLayout.CENTER));
video_pnl.add(loc_lbl);
control_pnl.add(createButton(increment));
video_pnl.add(control_pnl, BorderLayout.SOUTH);
video_pnl.revalidate();
add(video_pnl);
increment++;
}
}
private JButton createButton(final int i) {
play_btn = new JButton("Play");
play_btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
// System.out.println(file_location.get(i));
play(i);
}
});
return play_btn;
}
public void play(int i) {
System.out.println(file_location.get(i));
}
private class Handlers implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == btn_upload) {
try { //display the image in jlabel
file = new File("C:\\Users\\goldAnthony\\Documents\\NetBeansProjects\\VDMS\\src\\VideoInfos.txt");
if (!file.exists()) {
file.createNewFile();
file_writer = new FileWriter(file.getAbsolutePath());
} else {
file_writer = new FileWriter(file.getAbsolutePath(), true);
}
buffered_writer = new BufferedWriter(file_writer);
//creating a file chooser
filechooser = new JFileChooser();
filechooser.setDialogTitle("Choose Your Video");
// //below codes for select the file
int returnval = filechooser.showOpenDialog(null);
if (returnval == JFileChooser.APPROVE_OPTION) {
file = filechooser.getSelectedFile();
String filename = file.getAbsolutePath();
buffered_writer.write(filename);
buffered_writer.newLine();
buffered_writer.close();
}
} catch (IOException | HeadlessException ex) {
System.out.println(ex.getMessage());
}
}
}
}
public static void main(String[] args) throws IOException {
//Declare and initialize local variables
ArrayList<String> file_location = new ArrayList<>();
//creates instances of the VlcPlayer object, pass the mediaPath and invokes the method "run"
Media2 mediaplayer = new Media2(file_location);
JFrame ourframe = new JFrame();
ourframe.setContentPane(mediaplayer);
ourframe.setLayout(new GridLayout(5, 1));
ourframe.setSize(300, 560);
ourframe.setVisible(true);
ourframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
【问题讨论】：
-
我认为这会有所帮助，如果您添加更多上下文信息而不是仅仅发布整个应用程序代码。现在每个人都必须弄清楚问题的背景！
-
对 GUI 的更改最好在 Event Dispatch Thread 上完成，我看不到您在哪里更新...您的问题不清楚。
标签： java swing arraylist java-io