我已经能够使用与现在使用的相同的代码来保存输出图像，但是，当我更新应用程序时，似乎保存图像的代码现在已经以某种方式中断了。
如果我把它放到“合并”后保存文件以创建输出的状态下，它就可以正常工作，并且我已使用此方法来确保应用程序实际上正常工作。我确实希望应用程序的用户能够控制文件名，以使任何内容都不会被覆盖，而且正如我所说，它以前可以正常工作。
我用来保存图像的代码在这里：
private void saveButtonActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String fileName = JOptionPane.showInputDialog(null, "Save as...","");
save(fileName, combinedImage);
}
public static void save(String fileName, BufferedImage combinedImage) {
try {
File outputfile = new File(fileName+".png");
ImageIO.write(combinedImage, "png", outputfile);
JOptionPane.showMessageDialog(null, "File successfully saved as: "+outputfile);
System.out.println("File saved successfully: "+outputfile);
}
catch(IOException e) {
JOptionPane.showMessageDialog(null,"Save Image Error", "Save Image Error", WARNING_MESSAGE);
}
}
其中
combinedImage是我希望另存为PNG图像的输出。完整的错误消息也在这里：
Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: image == null!
at javax.imageio.ImageTypeSpecifier.createFromRenderedImage(ImageTypeSpecifier.java:925)
at javax.imageio.ImageIO.getWriter(ImageIO.java:1591)
at javax.imageio.ImageIO.write(ImageIO.java:1520)
at grey2RGB.save(grey2RGB.java:808)
at grey2RGB.saveButtonActionPerformed(grey2RGB.java:721)
at grey2RGB.access$2100(grey2RGB.java:29)
at grey2RGB$22.actionPerformed(grey2RGB.java:440)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:688)
at java.awt.EventQueue$3.run(EventQueue.java:686)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:702)
at java.awt.EventQueue$4.run(EventQueue.java:700)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:699)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
808行是
ImageIO.write(combinedImage, "png", outputfile);
721行是
save(fileName, combinedImage);
任何帮助，将不胜感激！
最佳答案
通常，这种问题是由于存在多个名为combinedImage的变量（并且使用了错误的变量）引起的。例如，检查：
在不同的地方没有多个称为combinedImage的变量
如果combinedImage是成员变量，则无论您希望在哪里使用同一对象的实例，都可以使用它
如果那没有帮助，请退出调试器并跟踪代码。