java - 如何通过jtextfield替换文件中的一行？

Question

这个程序允许用户搜索某个项目，然后该程序将这些项目拆分并将它们存储在 4 个不同的文本字段中。但是，下面是将检索到的项目更新回文件的方法。问题是每当用户单击更新按钮时，该行确实更新成功，但文件中的其他行被删除!

我使用arraylist来存储搜索到的项目，并使用临时文件来写入该项目，然后重命名它。

file.txt

ramal hotel1  10 uk

bren  hotel2  20 france

gil   hotel3  30 china

<小时/>

//Update to file
button9.addActionListener(new ActionListener(){
public  void actionPerformed(ActionEvent ae){

    try {

    String stringSearch = textfield1.getText();

    File filetemp = File.createTempFile("TempFileName", ".tmp", new File("/"));
    BufferedWriter writer = new BufferedWriter(new FileWriter(filetemp));
    File file = new File("file.txt");
    BufferedReader bf = new BufferedReader(new FileReader(file));


    int linecount = 0;
              String line;

    ArrayList<String> list = new ArrayList<String>();
    while (( line = bf.readLine()) != null){
    list.add(line);
    linecount++;


    int indexfound = line.indexOf(stringSearch);

    if (indexfound > -1) {

    String a = textfield1.getText();
    String b = textfield2.getText();
    String c = textfield3.getText();
    String d = textfield4.getText();




    String[] word = line.split("\t");
    String firstword = word[0];
    String secondword = word[1];
    String thirdword = word[2];
    String fourthword = word[3];




    writer.write(line.replace("\t", "\t").replace(firstword, b).replace(secondword, c).replace(thirdword, d));
    writer.flush();

    }

    writer.newLine();
    }
    writer.close();
    bf.close();
    filetemp.renameTo(file);
    filetemp.deleteOnExit();


    FileChannel src = new FileInputStream(filetemp).getChannel();
    FileChannel dest = new FileOutputStream(file).getChannel();
    dest.transferFrom(src, 0, src.size());



    }catch (IOException e) {

    System.out.println("IO Error Occurred: " + e.toString());

    }

}
});

Answer 1

您仅将该数据保存回包含您正在搜索的字符串的文件，而忽略其他行。

将其添加到代码中 if block 之后

else{
    writer.write(line);
    writer.flush();
}

就在以下行之前:

writer.newLine();

所以你的代码将如下所示:

//Update to file
button9.addActionListener(new ActionListener(){
public  void actionPerformed(ActionEvent ae){

    try {

    String stringSearch = textfield1.getText();

    File filetemp = File.createTempFile("TempFileName", ".tmp", new File("/"));
    BufferedWriter writer = new BufferedWriter(new FileWriter(filetemp));
    File file = new File("file.txt");
    BufferedReader bf = new BufferedReader(new FileReader(file));


    int linecount = 0;
              String line;

    ArrayList<String> list = new ArrayList<String>();
    while (( line = bf.readLine()) != null){
    list.add(line);
    linecount++;


    int indexfound = line.indexOf(stringSearch);

    if (indexfound > -1) {

    String a = textfield1.getText();
    String b = textfield2.getText();
    String c = textfield3.getText();
    String d = textfield4.getText();




    String[] word = line.split("\t");
    String firstword = word[0];
    String secondword = word[1];
    String thirdword = word[2];
    String fourthword = word[3];




    writer.write(line.replace("\t", "\t").replace(firstword, b).replace(secondword, c).replace(thirdword, d));
    writer.flush();

    }
    else{
        writer.write(line);
        writer.flush();
    }
    writer.newLine();
    }
    writer.close();
    bf.close();
    filetemp.renameTo(file);
    filetemp.deleteOnExit();


    FileChannel src = new FileInputStream(filetemp).getChannel();
    FileChannel dest = new FileOutputStream(file).getChannel();
    dest.transferFrom(src, 0, src.size());



    }catch (IOException e) {

    System.out.println("IO Error Occurred: " + e.toString());

    }

}
});