Dit is de code die ik momenteel heb:
public class FileStatus extends Status{
FileWriter writer;
public FileStatus(){
try {
writer = new FileWriter("status.txt",true);
} catch (IOException e) {
e.printStackTrace();
}
}
public void writeToFile(){
String file_text= pedStatusText + " " + gatesStatus + " " + DrawBridgeStatusText;
try {
writer.write(file_text);
writer.flush();
writer.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Alles werkt zoals verwacht (er wordt naar het bestand geschreven wanneer de methode writeToFile wordt aangeroepen). Maar wanneer de methode writeToFile een tweede keer wordt aangeroepen, krijg ik de volgende foutmelding:
java.io.IOException: Stream closed
at sun.nio.cs.StreamEncoder.ensureOpen(StreamEncoder.java:45)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:118)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:135)
at java.io.OutputStreamWriter.write(OutputStreamWriter.java:220)
at java.io.Writer.write(Writer.java:157)
at FileStatus.writeToFile(FileStatus.java:19)
at MenuBar$9.actionPerformed(MenuBar.java:115)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
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:703)
at java.awt.EventQueue.access$000(EventQueue.java:102)
at java.awt.EventQueue$3.run(EventQueue.java:662)
at java.awt.EventQueue$3.run(EventQueue.java:660)
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:676)
at java.awt.EventQueue$4.run(EventQueue.java:674)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:673)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)
java.io.IOException: Stream closed
at sun.nio.cs.StreamEncoder.ensureOpen(StreamEncoder.java:45)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:118)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:135)
at java.io.OutputStreamWriter.write(OutputStreamWriter.java:220)
at java.io.Writer.write(Writer.java:157)
at FileStatus.writeToFile(FileStatus.java:19)
at MenuBar$9.actionPerformed(MenuBar.java:115)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
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:703)
at java.awt.EventQueue.access$000(EventQueue.java:102)
at java.awt.EventQueue$3.run(EventQueue.java:662)
at java.awt.EventQueue$3.run(EventQueue.java:660)
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:676)
at java.awt.EventQueue$4.run(EventQueue.java:674)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:673)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)
java.io.IOException: Stream closed
at sun.nio.cs.StreamEncoder.ensureOpen(StreamEncoder.java:45)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:118)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:135)
at java.io.OutputStreamWriter.write(OutputStreamWriter.java:220)
at java.io.Writer.write(Writer.java:157)
at FileStatus.writeToFile(FileStatus.java:19)
at MenuBar$9.actionPerformed(MenuBar.java:115)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
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)
het bestand wordt nog steeds naar de tweede keer geschreven zoals verwacht, maar het geeft deze fout bij de tweede en toekomstige aanroepen van writeToFile(). Ik vraag me af waardoor deze fout wordt veroorzaakt.
Antwoord 1, autoriteit 100%
Je belt writer.close();
nadat je klaar bent met schrijven. Als een stream eenmaal is gesloten, kan er niet meer naar worden geschreven. Meestal is de manier waarop ik dit implementeer, door het sluiten van de methode schrijven naar te verplaatsen.
public void writeToFile(){
String file_text= pedStatusText + " " + gatesStatus + " " + DrawBridgeStatusText;
try {
writer.write(file_text);
writer.flush();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
En voeg een methode toe cleanUp
om de stream te sluiten.
public void cleanUp() {
writer.close();
}
Dit betekent dat je de verantwoordelijkheid hebt om ervoor te zorgen dat je cleanUp
aanroept als je klaar bent met schrijven naar het bestand. Als u dit niet doet, leidt dit tot geheugenlekken en blokkering van bronnen.
EDIT: u kunt elke keer dat u naar het bestand wilt schrijven een nieuwe stream maken door writer
naar de writeToFile()
methode..
public void writeToFile() {
FileWriter writer = new FileWriter("status.txt", true);
// ... Write to the file.
writer.close();
}
Antwoord 2, autoriteit 16%
Je roept writer.close();
aan in writeToFile
, dus de schrijver is gesloten de tweede keer dat je writeToFile
aanroept.
Waarom voeg je FileStatus
niet samen met writeToFile
?
Antwoord 3, autoriteit 10%
Bel write.close()
niet aan in writeToFile()
.