[JAVA] eccezione non aggiunge dati in MySQL

[elleone]

Cerco di inserire dati nel db MySQL provenienti da JTextField, però mi provoca un eccezione:

java.lang.NullPointerException
        at DB.inserire_db(DB.java:70)
        at nuovo.implementa(nuovo.java:179)
        at nuovo$1azioni.actionPerformed(nuovo.java:47)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:18
49)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.jav
a:2169)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel
.java:420)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258
)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonL
istener.java:234)
        at java.awt.Component.processMouseEvent(Component.java:5488)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3093)
        at java.awt.Component.processEvent(Component.java:5253)
        at java.awt.Container.processEvent(Container.java:1966)
        at java.awt.Component.dispatchEventImpl(Component.java:3955)
        at java.awt.Container.dispatchEventImpl(Container.java:2024)
        at java.awt.Component.dispatchEvent(Component.java:3803)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4212
)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3892)

        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3822)
        at java.awt.Container.dispatchEventImpl(Container.java:2010)
        at java.awt.Window.dispatchEventImpl(Window.java:1766)
        at java.awt.Component.dispatchEvent(Component.java:3803)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchTh
read.java:234)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:163)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)

        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)

        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)
java.lang.NullPointerException
        at DB.inserire_db(DB.java:70)
        at nuovo.implementa(nuovo.java:179)
        at nuovo$1azioni.actionPerformed(nuovo.java:47)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:18
49)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.jav
a:2169)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel
.java:420)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258
)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonL
istener.java:234)
        at java.awt.Component.processMouseEvent(Component.java:5488)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3093)
        at java.awt.Component.processEvent(Component.java:5253)
        at java.awt.Container.processEvent(Container.java:1966)
        at java.awt.Component.dispatchEventImpl(Component.java:3955)
        at java.awt.Container.dispatchEventImpl(Container.java:2024)
        at java.awt.Component.dispatchEvent(Component.java:3803)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4212
)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3892)

        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3822)
        at java.awt.Container.dispatchEventImpl(Container.java:2010)
        at java.awt.Window.dispatchEventImpl(Window.java:1766)
        at java.awt.Component.dispatchEvent(Component.java:3803)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchTh
read.java:234)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:163)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)

        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)

        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)
Press any key to continue...

metodo che si trova nella classe DB

	public void inserire_db(String nameTable, String nameAttributo, String dato)
	{
		try{
			Statement stm = db.createStatement(); <-- at DB.inserire_db(DB.java:70)
			stm.execute("INSERT INTO "+ nameTable + " ("+ nameAttributo +") " +	" VALUES('"+ dato + "') ");
										
		}catch(Exception e) { e.printStackTrace();	}
	}

metodo implementa

	if(event.getSource() == mod)
		{JPanel pp = new JPanel();
			database.connetti();
			
			for(int x = 0; x < schema[numItemCombo].length; x++)
			{
				
				String s = newTextField.get(x).getText();
-->		database.inserire_db(nameCombo, schema[numItemCombo][x], newTextField.get(x).getText() );  <--- at nuovo.implementa(nuovo.java:179)	
				JLabel leggi = new JLabel(s);
				JLabel li = new JLabel(nameCombo);
				JLabel liu = new JLabel(schema[numItemCombo][x]);
				
				pp.add(leggi);
				pp.add(li);
				pp.add(liu);
					
			}
			add(pp);
			//database.disconnetti();
			
			pannelloIndex.setVisible(false);
			pannelloInserire.setVisible(false);
		}

[LeleFT]

Semplicemente non hai istanziato la variabile db.
Dal codice non si evince, ma se dà una NullPointerException significa che l'oggetto db è nullo.


Ciao.