如何更新或删除.txt文件中的特定行？
[英]How to Update or delete a specific line from a .txt file?
问题描述
I already have methods to insert data in to a text file and search. 
我已经有了将数据插入文本文件并进行搜索的方法。 now I want methods for 'updating' and 'deleting' a selected record. 现在，我需要“更新”和“删除”所选记录的方法。
this is what I have done so far, 这是我到目前为止所做的
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? 有人可以帮我吗？ I want methods for: 我想要以下方法：
private void UpdatebuttonActionPerformed(java.awt.event.ActionEvent evt) {
}
private void DeleteButtonActionPerformed(java.awt.event.ActionEvent evt) {
}
Thanks in advance! 提前致谢！ :) :)
2 个解决方案
解决方案1
1 2015-06-22 13:11:54
I give you an example that i found. 我给你一个我发现的例子。 In this example i will replace a string inside of a line. 在此示例中，我将替换行内的字符串。 You can see that in my case im reading from a txt. 您可以看到在我的情况下，我正在从txt阅读。
/****** / ******
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: 结果：
Original: 原版的：
Original Text File Content: 原始文本文件内容：
Do the dishes0 Feed the dog0 Cleaned my room1 Output: 洗碗0喂狗0打扫房间1输出：
Do the dishes0 Feed the dog0 洗碗0喂狗0
Cleaned my room1 打扫我的房间1
Do the dishes1 Feed the dog0 Cleaned my room1 洗碗1喂狗0打扫房间1
Recent output: 最近的输出：
Do the dishes1 (HAS BEEN CHANGED) Feed the dog0 Cleaned my room1 洗碗1（已变）喂狗0打扫房间1
Maybe this example helps for you. 也许这个例子对你有帮助。
Regards! 问候！
解决方案2
0 2015-06-22 13:07:38
Read data to string. 读取数据到字符串。 Use string.replace(forDelte,""). 使用string.replace（forDelte，“”）。 And then just rewrite to txt file. 然后只需重写为txt文件即可。
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