Eccezione a Runtime che non capisco

[Nick083]

Ciao a tutti. Per la mia tesi devo fare un programma in Java con java.swing. Il problema mio è che non capisco perchè funziona tutto a parte un'eccezione a runtime che veramente non capisco, anche perchè non fa riferimento alle mie classi, ma a quelle "sopra" le mie...
Ho scoperto che il tutto nasce da questo codice qua:

        disaster.addItemListener(this);
        disaster.addItem("In");
        disaster.addItem("All");
        disaster.addItem("Bla");
        disaster_selezionato = disaster.getItemAt(0);
        JLabel label2 = new JLabel ("Ora prevista (ora e minuti): ");
        ora_selezionata = ora.getItemAt(0);
        ora.addItemListener(this);
        for (int i=1;i<24;i++)
            ora.addItem(i);
        minuti_selezionati = minuti.getItemAt(0);
        minuti.addItemListener(this);        
        for (int i=0;i<60;i++)
            minuti.addItem(i);
        JLabel label3 = new JLabel ("Tipo:      ");
        tipo_selezionato = tipo.getItemAt(0);
        tipo.addItemListener(this);
        tipo.addItem("Semplice");
        tipo.addItem("Dettagliata"); 

e mi dà questa eccezione:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.DefaultListCellRenderer.getListCellRen dererComponent(DefaultListCellRenderer.java:94)
at javax.swing.plaf.basic.BasicComboBoxUI.getDisplayS ize(BasicComboBoxUI.java:1291)
at javax.swing.plaf.basic.BasicComboBoxUI.getMinimumS ize(BasicComboBoxUI.java:875)
at javax.swing.plaf.basic.BasicComboBoxUI.getPreferre dSize(BasicComboBoxUI.java:865)
at com.sun.java.swing.plaf.windows.WindowsComboBoxUI. getPreferredSize(WindowsComboBoxUI.java:309)
at javax.swing.JComponent.getPreferredSize(JComponent .java:1632)
at java.awt.GridBagLayout.GetLayoutInfo(GridBagLayout .java:1092)
at java.awt.GridBagLayout.getLayoutInfo(GridBagLayout .java:893)
at java.awt.GridBagLayout.ArrangeGrid(GridBagLayout.j ava:2048)
at java.awt.GridBagLayout.arrangeGrid(GridBagLayout.j ava:2008)
at java.awt.GridBagLayout.layoutContainer(GridBagLayo ut.java:789)
at java.awt.Container.layout(Container.java:1432)
at java.awt.Container.doLayout(Container.java:1421)
at java.awt.Container.validateTree(Container.java:151 9)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validate(Container.java:1491)
at javax.swing.RepaintManager.validateInvalidComponen ts(RepaintManager.java:635)
at javax.swing.SystemEventQueueUtilities$ComponentWor kRequest.run(SystemEventQueueUtilities.java:127)
at java.awt.event.InvocationEvent.dispatch(Invocation Event.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 597)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:121)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.DefaultListCellRenderer.getListCellRen dererComponent(DefaultListCellRenderer.java:94)
at javax.swing.plaf.basic.BasicComboBoxUI.getDisplayS ize(BasicComboBoxUI.java:1291)
at javax.swing.plaf.basic.BasicComboBoxUI.getMinimumS ize(BasicComboBoxUI.java:875)
at javax.swing.plaf.basic.BasicComboBoxUI.getPreferre dSize(BasicComboBoxUI.java:865)
at com.sun.java.swing.plaf.windows.WindowsComboBoxUI. getPreferredSize(WindowsComboBoxUI.java:309)
at javax.swing.JComponent.getPreferredSize(JComponent .java:1632)
at java.awt.GridBagLayout.GetLayoutInfo(GridBagLayout .java:1092)
at java.awt.GridBagLayout.getLayoutInfo(GridBagLayout .java:893)
at java.awt.GridBagLayout.ArrangeGrid(GridBagLayout.j ava:2048)
at java.awt.GridBagLayout.arrangeGrid(GridBagLayout.j ava:2008)
at java.awt.GridBagLayout.layoutContainer(GridBagLayo ut.java:789)
at java.awt.Container.layout(Container.java:1432)
at java.awt.Container.doLayout(Container.java:1421)
at java.awt.Container.validateTree(Container.java:151 9)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validate(Container.java:1491)
at javax.swing.RepaintManager.validateInvalidComponen ts(RepaintManager.java:635)
at javax.swing.SystemEventQueueUtilities$ComponentWor kRequest.run(SystemEventQueueUtilities.java:127)
at java.awt.event.InvocationEvent.dispatch(Invocation Event.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 597)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:121)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.DefaultListCellRenderer.getListCellRen dererComponent(DefaultListCellRenderer.java:94)
at javax.swing.plaf.basic.BasicComboBoxUI.getDisplayS ize(BasicComboBoxUI.java:1291)
at javax.swing.plaf.basic.BasicComboBoxUI.getMinimumS ize(BasicComboBoxUI.java:875)
at javax.swing.plaf.basic.BasicComboBoxUI.getPreferre dSize(BasicComboBoxUI.java:865)
at com.sun.java.swing.plaf.windows.WindowsComboBoxUI. getPreferredSize(WindowsComboBoxUI.java:309)
at javax.swing.JComponent.getPreferredSize(JComponent .java:1632)
at java.awt.GridBagLayout.GetLayoutInfo(GridBagLayout .java:1092)
at java.awt.GridBagLayout.getLayoutInfo(GridBagLayout .java:893)
at java.awt.GridBagLayout.ArrangeGrid(GridBagLayout.j ava:2048)
at java.awt.GridBagLayout.arrangeGrid(GridBagLayout.j ava:2008)
at java.awt.GridBagLayout.layoutContainer(GridBagLayo ut.java:789)
at java.awt.Container.layout(Container.java:1432)
at java.awt.Container.doLayout(Container.java:1421)
at java.awt.Container.validateTree(Container.java:151 9)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validate(Container.java:1491)
at javax.swing.RepaintManager.validateInvalidComponen ts(RepaintManager.java:635)
at javax.swing.SystemEventQueueUtilities$ComponentWor kRequest.run(SystemEventQueueUtilities.java:127)
at java.awt.event.InvocationEvent.dispatch(Invocation Event.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 597)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:121)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.plaf.basic.BasicComboBoxUI.paintCurren tValue(BasicComboBoxUI.java:1164)
at com.sun.java.swing.plaf.windows.WindowsComboBoxUI. paintCurrentValue(WindowsComboBoxUI.java:293)
at javax.swing.plaf.basic.BasicComboBoxUI.paint(Basic ComboBoxUI.java:860)
at com.sun.java.swing.plaf.windows.WindowsComboBoxUI. paint(WindowsComboBoxUI.java:199)
at javax.swing.plaf.ComponentUI.update(ComponentUI.ja va:143)
at javax.swing.JComponent.paintComponent(JComponent.j ava:763)
at javax.swing.JComponent.paint(JComponent.java:1027)
at javax.swing.JComponent.paintChildren(JComponent.ja va:864)
at javax.swing.JComponent.paint(JComponent.java:1036)
at javax.swing.JComponent.paintToOffscreen(JComponent .java:5122)
at javax.swing.BufferStrategyPaintManager.paint(Buffe rStrategyPaintManager.java:285)
at javax.swing.RepaintManager.paint(RepaintManager.ja va:1128)
at javax.swing.JComponent._paintImmediately(JComponen t.java:5070)
at javax.swing.JComponent.paintImmediately(JComponent .java:4880)
at javax.swing.RepaintManager.paintDirtyRegions(Repai ntManager.java:723)
at javax.swing.RepaintManager.paintDirtyRegions(Repai ntManager.java:679)
at javax.swing.RepaintManager.seqPaintDirtyRegions(Re paintManager.java:659)
at javax.swing.SystemEventQueueUtilities$ComponentWor kRequest.run(SystemEventQueueUtilities.java:128)
at java.awt.event.InvocationEvent.dispatch(Invocation Event.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 597)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:121)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.DefaultListCellRenderer.getListCellRen dererComponent(DefaultListCellRenderer.java:94)
at javax.swing.plaf.basic.BasicComboBoxUI.getDisplayS ize(BasicComboBoxUI.java:1291)
at javax.swing.plaf.basic.BasicComboBoxUI.getMinimumS ize(BasicComboBoxUI.java:875)
at javax.swing.plaf.basic.BasicComboBoxUI.getPreferre dSize(BasicComboBoxUI.java:865)
at com.sun.java.swing.plaf.windows.WindowsComboBoxUI. getPreferredSize(WindowsComboBoxUI.java:309)
at javax.swing.JComponent.getPreferredSize(JComponent .java:1632)
at java.awt.GridBagLayout.GetLayoutInfo(GridBagLayout .java:1092)
at java.awt.GridBagLayout.getLayoutInfo(GridBagLayout .java:893)
at java.awt.GridBagLayout.ArrangeGrid(GridBagLayout.j ava:2048)
at java.awt.GridBagLayout.arrangeGrid(GridBagLayout.j ava:2008)
at java.awt.GridBagLayout.layoutContainer(GridBagLayo ut.java:789)
at java.awt.Container.layout(Container.java:1432)
at java.awt.Container.doLayout(Container.java:1421)
at java.awt.Container.validateTree(Container.java:151 9)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validateTree(Container.java:152 6)
at java.awt.Container.validate(Container.java:1491)
at javax.swing.RepaintManager.validateInvalidComponen ts(RepaintManager.java:635)
at javax.swing.SystemEventQueueUtilities$ComponentWor kRequest.run(SystemEventQueueUtilities.java:127)
at java.awt.event.InvocationEvent.dispatch(Invocation Event.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 597)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:121)

una cosa leggera insomma...

aiutatemi se potete... e.. BUONA PASQUA!!!

[Santino83_02]

stai usando un NULL come un oggetto a questa riga: at javax.swing.DefaultListCellRenderer.getListCellRen dererComponent(DefaultListCellRenderer.java:94)

[Nick083]

Si ok, però quella classe là non l'ho fatta io, ma era una calsse che già esiste... Quindi non è ch eposso modificarla... anche perchè non credo che cmq i programmatori abbiano messo una classe sbagliata, non credi?

[Nick083]

Ho scoperto che è qualcosa che a che fare con i JComboBox perchè se commento l'aggiunta di questi 4 elementi all'interno del pannello funziona tutto...

[R@ve M@ster]

Sicuramente non hai richiamato il metodo new per creare una istanza delle tue combo...

avrai fatto qualcosa del genere:

JComboBox disaster;
...

disaster.addItemListener(this); 
disaster.addItem("In"); 

che ovviamente genera una NullPointerException in quanto l'oggetto disaster (e non la classe scritta dagli altri) è nullo.

[Nick083]

eh si r@ve, magari fosse così semplice... Subito dopo una chiamata a super(), infatti, nel costruttore ho

disaster = new JComboBox();
ora = new JComboBox();
minuti = new JComboBox();
tipo = new JComboBox();

e anche se l'applicazione parte mi genera comunque questa eccezione (che, come già detto prima, non appartengono alle classi miei ma a quelle più "sopra"):

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.plaf.basic.BasicComboBoxUI.paintCurren tValue(BasicComboBoxUI.java:1164)
at com.sun.java.swing.plaf.windows.WindowsComboBoxUI. paintCurrentValue(WindowsComboBoxUI.java:293)
at javax.swing.plaf.basic.BasicComboBoxUI.paint(Basic ComboBoxUI.java:860)
at com.sun.java.swing.plaf.windows.WindowsComboBoxUI. paint(WindowsComboBoxUI.java:199)
at javax.swing.plaf.ComponentUI.update(ComponentUI.ja va:143)
at javax.swing.JComponent.paintComponent(JComponent.j ava:763)
at javax.swing.JComponent.paint(JComponent.java:1027)
at javax.swing.JComponent.paintChildren(JComponent.ja va:864)
at javax.swing.JComponent.paint(JComponent.java:1036)
at javax.swing.JComponent.paintChildren(JComponent.ja va:864)
at javax.swing.JComponent.paint(JComponent.java:1036)
at javax.swing.JComponent.paintToOffscreen(JComponent .java:5122)
at javax.swing.BufferStrategyPaintManager.paint(Buffe rStrategyPaintManager.java:285)
at javax.swing.RepaintManager.paint(RepaintManager.ja va:1128)
at javax.swing.JComponent._paintImmediately(JComponen t.java:5070)
at javax.swing.JComponent.paintImmediately(JComponent .java:4880)
at javax.swing.RepaintManager.paintDirtyRegions(Repai ntManager.java:723)
at javax.swing.RepaintManager.paintDirtyRegions(Repai ntManager.java:679)
at javax.swing.RepaintManager.seqPaintDirtyRegions(Re paintManager.java:659)
at javax.swing.SystemEventQueueUtilities$ComponentWor kRequest.run(SystemEventQueueUtilities.java:128)
at java.awt.event.InvocationEvent.dispatch(Invocation Event.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 597)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:121)

e dopo va avanti con altre 4 eccezioni uguali a questa (una per ogni JComboBox presente...)
AIUTO!!

[R@ve M@ster]

Posta il codice intero della classe. C'è sicuramente qualcosa altrove che ti sfugge.

[Nick083]

Questo è il codice completo della classe...

package drsimulator;

import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.event.*;

/**
 *
 * @author Mattia
 */
public class Panel1 extends Panel implements ItemListener {

    private int id_panel;
    private Object disaster_selezionato;
    private Object ora_selezionata;
    private Object minuti_selezionati;
    private Object tipo_selezionato;
    private JComboBox disaster;
    private JComboBox ora;
    private JComboBox minuti;
    private JComboBox tipo;
    
    public Panel1 () {
        
        super();
        id_panel=0;
        
        disaster = new JComboBox();
        ora =  new JComboBox();
        minuti =  new JComboBox();
        tipo = new JComboBox();
        
        //Creazione del Layout per il pannello
        GridBagLayout gridbag = new GridBagLayout();
        GridBagConstraints constraints = new GridBagConstraints ();
        setLayout(gridbag);
        
        //Creazione degli elementi presenti nel pannello
        JLabel label = new JLabel ("SIMULATORE");
        label.setFont (new Font("MS Sans Serif", Font.BOLD, 20));
        label.setForeground(Color.BLUE);
        JLabel label1 = new JLabel ("A:     ");
        disaster.addItemListener(this);
        disaster.addItem("In");
        disaster.addItem("All");
        disaster.addItem("Out");
        disaster_selezionato = disaster.getItemAt(0);
        JLabel label2 = new JLabel ("Ora prevista: ");
        ora_selezionata = ora.getItemAt(0);
        ora.addItemListener(this);
       for (int i=1;i<24;i++)
            ora.addItem(i);
        minuti_selezionati = minuti.getItemAt(0);
        minuti.addItemListener(this);        
        for (int i=0;i<60;i++)
            minuti.addItem(i);
        JLabel label3 = new JLabel ("Tipo:      ");
        tipo_selezionato = tipo.getItemAt(0);
        tipo.addItemListener(this);
        tipo.addItem("Semplice");
        tipo.addItem("Dettagliata");
        
        //Disposizione degli elementi appena creati
        buildConstraints (constraints, 0, 0, 3, 1, 100, 10);
        gridbag.setConstraints (label, constraints);
        add(label);
        buildConstraints (constraints, 0, 1, 1, 1, 50, 20);
        constraints.anchor = GridBagConstraints.WEST;
        gridbag.setConstraints (label1, constraints);
        add(label1);
        buildConstraints (constraints, 1, 1, 1, 1, 50, 20);
        gridbag.setConstraints (disaster, constraints);
        constraints.anchor = GridBagConstraints.WEST;
        this.add(disaster);
        buildConstraints (constraints, 0, 2, 1, 1, 50, 20);
        gridbag.setConstraints (label2, constraints);
        constraints.anchor = GridBagConstraints.EAST;
        add(label2);
        buildConstraints (constraints, 1, 2, 1, 1, 25, 20);
        gridbag.setConstraints (ora, constraints);
        constraints.anchor = GridBagConstraints.WEST;
        this.add(ora);
        buildConstraints (constraints, 2, 2, 1, 1, 25, 20);
        gridbag.setConstraints (minuti, constraints);
        constraints.anchor = GridBagConstraints.WEST;
        this.add(minuti);
        buildConstraints (constraints, 0, 3, 1, 1, 50, 20);
        gridbag.setConstraints (label3, constraints);
        constraints.anchor = GridBagConstraints.WEST;
        add(label3);
        buildConstraints (constraints, 1, 3, 1, 1, 50, 20);
        gridbag.setConstraints (tipo, constraints);
        constraints.anchor = GridBagConstraints.WEST;
        this.add(tipo);
    }
    
    //Ritorna l'id di Panel1
    public int getIdPanel () {
        return id_panel;
    }
    
    //Setta l'id del di Panel1
    public void setIdPanel (int i) {
        this.id_panel=i;
    }
    
    //Dispone un elemento in posizione
    public void buildConstraints (GridBagConstraints gbc, int gx, int gy, int gw, int gh, int wx, int wy) {
        gbc.gridx = gx;
        gbc.gridy = gy;
        gbc.gridheight = gh;
        gbc.gridwidth = gw;
        gbc.weightx = wx;
        gbc.weighty = wy;
    }
    
    //Funzione che verifica il cambio di stato
    public void itemStateChanged (ItemEvent evt) {
        Object source = evt.getSource();
        if (source == disaster) {
            Object newDisaster = evt.getItem();
            disaster_selezionato = (String)newDisaster;
        }
        else if (source == ora) {
            Object newDisaster = evt.getItem();
            ora_selezionata = (Integer)newDisaster;
        }
        else if (source == minuti) {
            Object newDisaster = evt.getItem();
            minuti_selezionati = (Integer)newDisaster;
        }
        else {
            Object newDisaster = evt.getItem();
            tipo_selezionato = (String)newDisaster;
        }
    }
}

[LeleFT]

@Nick083: quando posti il codice, fallo all'interno dei tag [CODE] e [/CODE], così da renderlo leggibile.

Ho modificato il tuo post precedente, proprio per aggiungere tali tag al codice.


Ciao.

[Nick083]

Grazie lele, scusa...

cmq qualcuno è riuscito a trovare l'inghippo???