NullPointerException -- 3ICT oefeningen

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Subject: NullPointerException

Author:
Rik VW

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Date Posted: 11:24:48 04/28/02 Sun

Bij een oefening ben ik een rare fout tegengekomen. Data worden in een Vector gestopt (ic Strings). De String zit er zeker in want bij System.out.println(data.elementAt(0)); krijg ik het element terug in de uitvoer. Als ik dan echter een JList die data wil doorgeven geeft hij in runtime een NullPointerException. Oekandana?

Code volgt:

public void actionPerformed(ActionEvent e) {
JButton bron = (JButton) e.getSource();
if (bron == toevoegen) {
data.addElement(vakT.getText() + " " + ptnT.getText());
System.out.println(data.elementAt(0));
//Geeft fout NullPointer alhoewel er wel degelijk iets inzit
lijst.setListData(data);
lijst.repaint();
vakT.setText("");
ptnT.setText("");
tabel = new JScrollPane (lijst);
}
else {
try {
Object []dataArray = data.toArray();
FileWriter fw = new FileWriter (klas);
for (int i=0; i < dataArray.length; i++)
fw.write(dataArray[i]+"\n");
fw.write("*\n");
fw.close();
// Nieuwe namen toevoegen in de klas
Frame namen = new NamenFrame();
// Geen BufferedWriter nodig???
dispose();
} catch (IOException ioex) {
System.out.println(ioex);
}
}
}

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Replies:

Subject	Author	Date
Re: NullPointerException	Johan	16:59:00 04/28/02 Sun