How to Update or delete a specific line from a .txt file?
Question
I already have methods to insert data in to a text file and search. now I want methods for 'updating' and 'deleting' a selected record.
this is what I have done so far,
private void InsertbuttonActionPerformed(java.awt.event.ActionEvent evt) {
fileWriter = null;
try {
String phone = Phone.getText();
String fname = Fname.getText();
String lname = Lname.getText();
String nic = NIC.getText();
String city = City.getSelectedItem().toString();
fileWriter = new FileWriter(file, true);
fileWriter.append(phone + "|" + fname + "|" + lname + "|" + nic + "|" + city+ "|");
fileWriter.append("\r\n");
fileWriter.flush();
JOptionPane.showMessageDialog(InsertGUI.this, "<html> " + phone + " <br> Successfully saved! </html>");
Phone.setText(null);
NIC.setText(null);
Fname.setText(null);
Lname.setText(null);
City.setSelectedIndex(0);
} catch (IOException ex) {
Logger.getLogger(InsertGUI.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
fileWriter.close();
} catch (IOException ex) {
Logger.getLogger(InsertGUI.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
private void searchbuttonActionPerformed(java.awt.event.ActionEvent evt) {
try {
fileReader = new FileReader(file);
BufferedReader br = new BufferedReader(fileReader);
String selectedphone = SearchF.getText();
String content = "";
String temp = "";
try {
while ((temp = br.readLine()) != null) {
content += temp;
}
} catch (IOException ex) {
Logger.getLogger(UpdateGUI.class.getName()).log(Level.SEVERE, null, ex);
}
HashMap<String, String> map = new HashMap();
StringTokenizer stringTokenizer = new StringTokenizer(content, "|");
boolean found = false;
while (stringTokenizer.hasMoreTokens()) {
String phone = stringTokenizer.nextElement().toString();
String fname = stringTokenizer.nextElement().toString();
String lname = stringTokenizer.nextElement().toString();
String nic = stringTokenizer.nextElement().toString();
String city = stringTokenizer.nextElement().toString();
if (phone.equalsIgnoreCase(selectedphone)) {
Phone.setText(phone);
NIC.setText(nic);
Fname.setText(fname);
Lname.setText(lname);
switch (city) {
case "Ambalangoda":
City.setSelectedIndex(0);
break;
case "Ampara":
City.setSelectedIndex(1);
break;
case "Anuradhapura":
City.setSelectedIndex(2);
break;
case "Avissawella":
City.setSelectedIndex(3);
break;
case "Badulla":
City.setSelectedIndex(4);
break;
case "Balangoda":
City.setSelectedIndex(5);
break;
}
found = true;
}
}
if (!found) {
JOptionPane.showMessageDialog(UpdateGUI.this, "Phone number not found!");
Phone.setText(null);
NIC.setText(null);
Fname.setText(null);
Lname.setText(null);
City.setSelectedIndex(0);
}
} catch (FileNotFoundException ex) {
Logger.getLogger(UpdateGUI.class.getName()).log(Level.SEVERE, null, ex);
}
}
can someone please help me with this? I want methods for:
private void UpdatebuttonActionPerformed(java.awt.event.ActionEvent evt) {
}
private void DeleteButtonActionPerformed(java.awt.event.ActionEvent evt) {
}
Thanks in advance! :)
2 answers
solution1
1 2015-06-22 13:11:54
I give you an example that i found. In this example i will replace a string inside of a line. You can see that in my case im reading from a txt.
/******
public static void replaceSelected(String replaceWith, String type) {
try {
// input the file content to the String "input"
BufferedReader file = new BufferedReader(new FileReader("notes.txt"));
String line;String input = "";
while ((line = file.readLine()) != null) input += line + '\n';
file.close();
System.out.println(input); // check that it's inputted right
// this if structure determines whether or not to replace "0" or "1"
if (Integer.parseInt(type) == 0) {
input = input.replace(replaceWith + "1", replaceWith + "0");
}
else if (Integer.parseInt(type) == 1) {
input = input.replace(replaceWith + "0", replaceWith + "1");
}
// check if the new input is right
System.out.println("----------------------------------" + '\n' + input);
// write the new String with the replaced line OVER the same file
FileOutputStream fileOut = new FileOutputStream("notes.txt");
fileOut.write(input.getBytes());
fileOut.close();
} catch (Exception e) {
System.out.println("Problem reading file.");
}
}
public static void main(String[] args) {
replaceSelected("Do the dishes","1");
}
*/
Result:
Original:
Original Text File Content:
Do the dishes0 Feed the dog0 Cleaned my room1 Output:
Do the dishes0 Feed the dog0
Cleaned my room1
Do the dishes1 Feed the dog0 Cleaned my room1
Recent output:
Do the dishes1 (HAS BEEN CHANGED) Feed the dog0 Cleaned my room1
Maybe this example helps for you.
Regards!
solution2
0 2015-06-22 13:07:38
Read data to string. Use string.replace(forDelte,""). And then just rewrite to txt file.
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