我是新来的swing,并试图编写一个代码,在JFrame上有一个按钮,点击它可以打开一个JFileChooser来选择一个图像,用户选择后,它会显示它thr JFrame,但我一直得到Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
,我发现我不能设置选定的图像图标到JPanel,这让我疯狂,请帮助我!
我的代码是:
无法将imageicon设置为JLabel,始终为空
public class ImageLoading extends JFrame{
private static final int FRAME_WIDTH = 500;
private static final int FRAME_HEIFHT = 500;
private BufferedImage mImage;
private JFrame frm;
private JPanel panel;
private JButton button;
String name,name1;
public class ButtonListener implements ActionListener{
public void actionPerformed(ActionEvent event){
String source=filechoose();
File inputFile = new File(source);
System.out.println("File Directory: " + inputFile.toString());
try {
mImage = ImageIO.read(inputFile);
System.out.println("Buffered Image: " + mImage.toString());
} catch (IOException ex) {
System.out.println(ex.getMessage());
}
ImageIcon image = new ImageIcon(mImage);
System.out.println("Image Icon: " + image.toString() + " ::: " +image.getIconHeight());
JLabel lb = new JLabel(image);// HERE I GET EXCEPTION
System.out.println("Image Label: " + lb.toString());
panel.add(lb);
panel.revalidate();
panel.repaint();
frm.pack();
}
}
public void imageLoading(){
frm = new JFrame("image loading test");
frm.setLayout(null);
JLabel label2 = new JLabel("Open a picture");
button = new JButton("Open");
panel = new JPanel();
panel.setBounds(10, 10, 400, 400);
panel.add(button);
panel.add(label2);
ImageLoading load = new ImageLoading();
ButtonListener listener = load.new ButtonListener();
button.addActionListener(listener);
frm.add(panel);
frm.setSize(FRAME_WIDTH,FRAME_HEIFHT);
frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frm.setVisible(true);
}
public String filechoose(){
JFileChooser chooser = new JFileChooser();
chooser.setFileFilter(new javax.swing.filechooser.FileFilter() {
public boolean accept(File f) {
name = f.getName().toLowerCase();
return name.endsWith(".gif") || name.endsWith(".jpg")
|| name.endsWith(".jpeg") || f.isDirectory();
}
public String getDescription() {
return "Image files";
}
});
int r = chooser.showOpenDialog(this);
if (r == JFileChooser.APPROVE_OPTION) {
name1 = chooser.getSelectedFile().getAbsolutePath();
StringBuffer sb=new StringBuffer();
sb.append(name1);
int l=sb.length();
for(int i=0;i<l;i++){
if(sb.charAt(i)=='\\'){
sb.insert(i, "\\");
}
}
}
return name1;
}
public static void main(String a[]){
ImageLoading i = new ImageLoading();
i.imageLoading();
}
` 请帮我这或给我一些样品做这个....谢谢!
愚蠢的问题,但'System.out.println(“Buffered Image:”+ mImage.toString());'打印出来?在上一行中可能会导致mImage为null – 2013-03-11 02:05:09