Java:
//Methode soll alle Daten aus Kontakte (eine information pro zeile) in temporäre datei schreiben außer die zu löschenden informationen
BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream("kontakte.txt")));
BufferedReader reader1 = new BufferedReader(new InputStreamReader(new FileInputStream("kontaktetemp.txt")));
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("kontaktetemp.txt", true)));
BufferedWriter finish = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("kontakte.txt", true)));
String line = "";
BufferedWriter tdel = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("kontaktetemp.txt", false)));
tdel.write(""); //löscht alles im temporären txt
tdel.close();
while (line != null) {
line = reader.readLine();
if (line == name) {line = reader.readLine(); line = reader.readLine(); line = reader.readLine();} //wenn zu löschende info = line ist werden 3 zeilen übersprungen (alles was zu löschen ist)
writer.write(line); //schreibt in temp file
}
writer.close();
reader.close();
String line1 = "";
BufferedWriter kdel = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("kontakte.txt", false)));
kdel.write(""); //löscht alles im hauptfile
kdel.close();
while (line1 != null) {
line1 = reader1.readLine();
finish.write(line1); //schreibt alles aus temp file in kontakt file
}
reader1.close();
finish.close();
Warum tritt eine nullpointer exception auf?
Zuletzt bearbeitet: