&引用;AWT-EventQueue-0“;保存JTable时的java.lang.NullPointerException(DefaultTableModel)
我在保存&引用;AWT-EventQueue-0“;保存JTable时的java.lang.NullPointerException(DefaultTableModel),java,swing,exception,nullpointerexception,jtable,Java,Swing,Exception,Nullpointerexception,Jtable,我在保存JTable(包含模型)时遇到问题。只要我只添加行和数据,简单地序列化模型就没有问题。当我删除一行并尝试保存时,会生成一个IO异常。我的代码: 此代码用于保存模型: public static void saveModel() { if (isDatabasePathSet == true) { FileOutputStream fos = null; ObjectOutputStream out = null;
JTable
(包含模型)时遇到问题。只要我只添加行和数据,简单地序列化模型就没有问题。当我删除一行并尝试保存时,会生成一个IO异常。我的代码:
此代码用于保存模型:
public static void saveModel() {
if (isDatabasePathSet == true) {
FileOutputStream fos = null;
ObjectOutputStream out = null;
try {
table.clearSelection();
table.repaint();
if (table.isEditing()) { // prevent saving when user is editing a cell
table.getCellEditor().stopCellEditing();
}
fos = new FileOutputStream("test" + ".dbd");
out = new ObjectOutputStream(fos);
out.writeObject(model); // here I save the table contents
out.writeObject(lfdNr); // this is just an increasing number / primary key
} catch (Exception errWrite) {
System.out.println("Fehler beim speichern der Datenbank");
} finally {
try {
fos.close();
out.close();
} catch (Exception errClose) {
System.out.println("Fehler beim Schließen der Dateiströme");
}
}
} else {
JOptionPane
.showMessageDialog(
mainGui,
"<html>Es ist keine Datenbank ausgewählt, <br>bitte wählen Sie zunächst eine Datenbank im Menü aus: <br><br><i>Datenbank --> Datenbankpfad festlegen...</i></html>",
"Datenbankpfad fehlt", JOptionPane.WARNING_MESSAGE);
}
}
model = new DefaultTableModel(new Object[][] { },
new String[] { "Lfd. Nr.", "FB Nr.", "Melde Nr.", "Betra Nr.", "Datum",
"Ort", "Str. Km.", "Sprz.", "Mitarbeiter",
"Auftrag / Objekt(e)", "Abgeschlossen" }) {
private static final long serialVersionUID = 1L;
Class[] columnTypes = new Class[] { Integer.class, String.class, Integer.class,
Integer.class, String.class, String.class, String.class,
String.class, String.class, String.class, Boolean.class };
public Class getColumnClass(int columnIndex) {
return columnTypes[columnIndex];
}
};
JButton buttonDeleteTask = new JButton("Auftrag entfernen");
buttonDeleteTask.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int selectedRows[] = table.getSelectedRows();
for (int i = 0; i < selectedRows.length; i++) {
model.removeRow(selectedRows[i] - i);
}
}
});
Fehler beim speichern der Datenbank
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.plaf.basic.BasicTableUI.paint(BasicTableUI.java:1761)
at javax.swing.plaf.ComponentUI.update(ComponentUI.java:161)
at javax.swing.JComponent.paintComponent(JComponent.java:779)
at javax.swing.JComponent.paint(JComponent.java:1055)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JViewport.paint(JViewport.java:731)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JSplitPane.paintChildren(JSplitPane.java:1047)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JLayeredPane.paint(JLayeredPane.java:585)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JComponent.paintToOffscreen(JComponent.java:5232)
at javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:295)
at javax.swing.RepaintManager.paint(RepaintManager.java:1249)
at javax.swing.JComponent._paintImmediately(JComponent.java:5180)
at javax.swing.JComponent.paintImmediately(JComponent.java:4991)
at javax.swing.RepaintManager$3.run(RepaintManager.java:808)
at javax.swing.RepaintManager$3.run(RepaintManager.java:796)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:796)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:769)
at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:718)
at javax.swing.RepaintManager.access$1100(RepaintManager.java:62)
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1677)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:312)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:738)
at java.awt.EventQueue.access$300(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:699)
at java.awt.EventQueue$3.run(EventQueue.java:697)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:708)
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)
我删除这样一行:
public static void saveModel() {
if (isDatabasePathSet == true) {
FileOutputStream fos = null;
ObjectOutputStream out = null;
try {
table.clearSelection();
table.repaint();
if (table.isEditing()) { // prevent saving when user is editing a cell
table.getCellEditor().stopCellEditing();
}
fos = new FileOutputStream("test" + ".dbd");
out = new ObjectOutputStream(fos);
out.writeObject(model); // here I save the table contents
out.writeObject(lfdNr); // this is just an increasing number / primary key
} catch (Exception errWrite) {
System.out.println("Fehler beim speichern der Datenbank");
} finally {
try {
fos.close();
out.close();
} catch (Exception errClose) {
System.out.println("Fehler beim Schließen der Dateiströme");
}
}
} else {
JOptionPane
.showMessageDialog(
mainGui,
"<html>Es ist keine Datenbank ausgewählt, <br>bitte wählen Sie zunächst eine Datenbank im Menü aus: <br><br><i>Datenbank --> Datenbankpfad festlegen...</i></html>",
"Datenbankpfad fehlt", JOptionPane.WARNING_MESSAGE);
}
}
model = new DefaultTableModel(new Object[][] { },
new String[] { "Lfd. Nr.", "FB Nr.", "Melde Nr.", "Betra Nr.", "Datum",
"Ort", "Str. Km.", "Sprz.", "Mitarbeiter",
"Auftrag / Objekt(e)", "Abgeschlossen" }) {
private static final long serialVersionUID = 1L;
Class[] columnTypes = new Class[] { Integer.class, String.class, Integer.class,
Integer.class, String.class, String.class, String.class,
String.class, String.class, String.class, Boolean.class };
public Class getColumnClass(int columnIndex) {
return columnTypes[columnIndex];
}
};
JButton buttonDeleteTask = new JButton("Auftrag entfernen");
buttonDeleteTask.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int selectedRows[] = table.getSelectedRows();
for (int i = 0; i < selectedRows.length; i++) {
model.removeRow(selectedRows[i] - i);
}
}
});
Fehler beim speichern der Datenbank
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.plaf.basic.BasicTableUI.paint(BasicTableUI.java:1761)
at javax.swing.plaf.ComponentUI.update(ComponentUI.java:161)
at javax.swing.JComponent.paintComponent(JComponent.java:779)
at javax.swing.JComponent.paint(JComponent.java:1055)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JViewport.paint(JViewport.java:731)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JSplitPane.paintChildren(JSplitPane.java:1047)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JLayeredPane.paint(JLayeredPane.java:585)
at javax.swing.JComponent.paintChildren(JComponent.java:888)
at javax.swing.JComponent.paint(JComponent.java:1064)
at javax.swing.JComponent.paintToOffscreen(JComponent.java:5232)
at javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:295)
at javax.swing.RepaintManager.paint(RepaintManager.java:1249)
at javax.swing.JComponent._paintImmediately(JComponent.java:5180)
at javax.swing.JComponent.paintImmediately(JComponent.java:4991)
at javax.swing.RepaintManager$3.run(RepaintManager.java:808)
at javax.swing.RepaintManager$3.run(RepaintManager.java:796)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:796)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:769)
at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:718)
at javax.swing.RepaintManager.access$1100(RepaintManager.java:62)
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1677)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:312)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:738)
at java.awt.EventQueue.access$300(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:699)
at java.awt.EventQueue$3.run(EventQueue.java:697)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:708)
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)
我看不出在AWT EventQue中从何处获得空指针,在序列化之前是否必须更新模型 好吧,我发现了我的问题。在序列化之前,需要将模型从表中分离,否则将失败。所以序列化现在看起来像这样:
[...]
fos = new FileOutputStream("03032015.dbd");
out = new ObjectOutputStream(fos);
table.setModel(new DefaultTableModel()); // detach model from table while serializing to prevent it from failing
out.writeObject(model);
table.setModel(model);
[...]
保存后,可以毫无问题地重新应用旧模型
多亏了DSquare和Andrew Thompson,我尝试了MCVE(最小完全可验证示例)或SSCCE(简短、自包含、正确的示例)方法,这使我想到了这篇文章:查看源代码,这是因为
table.getBounds()
返回不应该返回的null。检查该值以查看何时发生。是否在EDT中调用了saveModel
?要更快地获得更好的帮助,请发布(最小完整可验证示例)或(简短、自包含、正确的示例)。@DSquare我在哪里可以找到“table.getBounds()”调用?我在我的代码中找不到它,是什么调用了这个方法?@Flatron,如1761行的堆栈跟踪所示。好的,但我如何解决这个问题,我可以手动设置边界。但是,这与只有删除一行时才会发生错误这一事实有什么关系呢?也许删除一行会将边界重置为空指针。有趣!当你以一种非常干净的方式处理你的问题时(做MCVE/SCCE),通常会发生这种情况。你可以接受你自己的答案!