Dynamically Displaying data into TableView from Database ERROR IN cellvaluefactory - sql

Question

Can anyone Help?
I want to dynamically display my Database content into TableView in FXML file.
The Code works when I don't have any null Value in any of the column database.
I expected the code should display empty space in TableView of FXML when my database column has a null value.
dateOfIssue.setCellValueFactory(new Callback<CellDataFeatures<ObservableList, String>, ObservableValue<String>>() {
public ObservableValue<String> call(CellDataFeatures<ObservableList, String> param) {
return new SimpleStringProperty(param.getValue().get(2).toString());
}
});
studentID.setCellValueFactory(new Callback<CellDataFeatures<ObservableList, String>, ObservableValue<String>>() {
public ObservableValue<String> call(CellDataFeatures<ObservableList, String> param) {
return new SimpleStringProperty(param.getValue().get(3).toString());
}
});
primary.setCellValueFactory(new Callback<CellDataFeatures<ObservableList, String>, ObservableValue<String>>() {
public ObservableValue<String> call(CellDataFeatures<ObservableList, String> param) {
return new SimpleStringProperty(param.getValue().get(0).toString());
}
});
secondary.setCellValueFactory(new Callback<CellDataFeatures<ObservableList, String>, ObservableValue<String>>() {
public ObservableValue<String> call(CellDataFeatures<ObservableList, String> param) {
return new SimpleStringProperty(param.getValue().get(1).toString());
}
});
I have my secondary column as null at few rows.here is my error.
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at library.DatabaseController$4.call(DatabaseController.java:105)
at library.DatabaseController$4.call(DatabaseController.java:103)
at javafx.scene.control.TableColumn.getCellObservableValue(TableColumn.java:578)
at javafx.scene.control.TableColumn.getCellObservableValue(TableColumn.java:563)
at javafx.scene.control.TableCell.updateItem(TableCell.java:644)
at javafx.scene.control.TableCell.indexChanged(TableCell.java:468)
at javafx.scene.control.IndexedCell.updateIndex(IndexedCell.java:116)
at com.sun.javafx.scene.control.skin.TableRowSkinBase.updateCells(TableRowSkinBase.java:533)
at com.sun.javafx.scene.control.skin.TableRowSkinBase.init(TableRowSkinBase.java:147)
at com.sun.javafx.scene.control.skin.TableRowSkin.<init>(TableRowSkin.java:64)
at javafx.scene.control.TableRow.createDefaultSkin(TableRow.java:212)
at javafx.scene.control.Control.impl_processCSS(Control.java:872)
at javafx.scene.Node.processCSS(Node.java:9058)
at javafx.scene.Node.applyCss(Node.java:9155)
at com.sun.javafx.scene.control.skin.VirtualFlow.setCellIndex(VirtualFlow.java:1964)
at com.sun.javafx.scene.control.skin.VirtualFlow.addTrailingCells(VirtualFlow.java:1344)
at com.sun.javafx.scene.control.skin.VirtualFlow.layoutChildren(VirtualFlow.java:1197)
at javafx.scene.Parent.layout(Parent.java:1087)
at javafx.scene.Parent.layout(Parent.java:1093)
at javafx.scene.Parent.layout(Parent.java:1093)
at javafx.scene.Parent.layout(Parent.java:1093)
at javafx.scene.Parent.layout(Parent.java:1093)
at javafx.scene.Scene.doLayoutPass(Scene.java:552)
at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:2397)
at com.sun.javafx.tk.Toolkit.lambda$runPulse$29(Toolkit.java:398)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.Toolkit.runPulse(Toolkit.java:397)
at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:424)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:518)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:498)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulseFromQueue(QuantumToolkit.java:491)
at com.sun.javafx.tk.quantum.QuantumToolkit.lambda$runToolkit$403(QuantumToolkit.java:319)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
at java.lang.Thread.run(Thread.java:748)
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at library.DatabaseController$4.call(DatabaseController.java:105)
at library.DatabaseController$4.call(DatabaseController.java:103)
at javafx.scene.control.TableColumn.getCellObservableValue(TableColumn.java:578)
at javafx.scene.control.TableColumn.getCellObservableValue(TableColumn.java:563)
at javafx.scene.control.TableCell.updateItem(TableCell.java:644)
at javafx.scene.control.TableCell.indexChanged(TableCell.java:468)
at javafx.scene.control.IndexedCell.updateIndex(IndexedCell.java:116)
at com.sun.javafx.scene.control.skin.TableRowSkinBase.updateCells(TableRowSkinBase.java:533)
at com.sun.javafx.scene.control.skin.TableRowSkinBase.init(TableRowSkinBase.java:147)
at com.sun.javafx.scene.control.skin.TableRowSkin.<init>(TableRowSkin.java:64)
at javafx.scene.control.TableRow.createDefaultSkin(TableRow.java:212)
at javafx.scene.control.Control.impl_processCSS(Control.java:872)
at javafx.scene.Parent.impl_processCSS(Parent.java:1280)
at javafx.scene.Parent.impl_processCSS(Parent.java:1280)
at javafx.scene.Parent.impl_processCSS(Parent.java:1280)
at javafx.scene.Parent.impl_processCSS(Parent.java:1280)
at javafx.scene.control.Control.impl_processCSS(Control.java:868)
at javafx.scene.Node.processCSS(Node.java:9058)
at javafx.scene.Node.processCSS(Node.java:9051)
at javafx.scene.Node.processCSS(Node.java:9051)
at javafx.scene.Node.processCSS(Node.java:9051)
at javafx.scene.Scene.doCSSPass(Scene.java:545)
at javafx.scene.Scene.access$3600(Scene.java:159)
at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:2392)
at com.sun.javafx.tk.Toolkit.lambda$runPulse$29(Toolkit.java:398)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.Toolkit.runPulse(Toolkit.java:397)
at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:424)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:518)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:498)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulseFromQueue(QuantumToolkit.java:491)
at com.sun.javafx.tk.quantum.QuantumToolkit.lambda$runToolkit$403(QuantumToolkit.java:319)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
at java.lang.Thread.run(Thread.java:748)

Answer 1

I assume your issue is at below point. If your value is null, obviously you will get NPE when accessing toString(). Try to do some null checks before calling toString().
param.getValue().get(1).toString()

Answer 2

If one of the ObservableLists contains null, trying to invoke toString for such an object results in the NullPointerException. I recommend using different code to convert to a string, e.g. Objects.toString:
secondary.setCellValueFactory(new Callback<CellDataFeatures<ObservableList, String>, ObservableValue<String>>() {
#Override
public ObservableValue<String> call(CellDataFeatures<ObservableList, String> param) {
return new SimpleStringProperty(Objects.toString(param.getValue().get(1), ""));
}
});