Question

我知道已经有一些关于这个问题的帖子，但我不了解它们。我的问题是我想在带有名称的txt文档中找到一行，然后我想将下一行更改为字符串的内容。

这就是我的尝试：

public void saveDocument(String name) {

    String documentToSave = textArea1.getText();

    File file = new File("documents.txt");

    Scanner scanner;

    BufferedWriter bw;

    try {

        scanner = new Scanner(file);

        bw = new BufferedWriter(new FileWriter(file));

        while(scanner.hasNextLine()) {

            if(scanner.nextLine().equals(name)) {

                if(scanner.hasNextLine()) bw.write(scanner.nextLine() + "\n");
                bw.write(documentToSave + "\n");
                if(scanner.hasNextLine()) scanner.nextLine();

            }

            if(scanner.hasNextLine()) bw.write(scanner.nextLine() + "\n");

        }

        bw.flush();
        bw.close();

    } catch (IOException e) {

        e.printStackTrace();

    }

}

Answer 1

此代码应读取整个文件并用名称替换该行。

Dictionary

Answer 2

此程序将替换给定行之后的行。它需要我们的更多工作，例如，如果我们可以定义预期的i / o和使用。现在它从文件中读取并重新放置一行，但是您可能希望使用行号而不是行内容来标记要替换的行。

import java.io.*;
public class FileLineReplace {
 public static void replaceSelected(String replaceWith, String type) {
  try {
   String input2 = "";
   boolean replace = false;

   String input = "";

   try (BufferedReader br = new BufferedReader(new FileReader("data.txt"))) {
    for (String line;
     (line = br.readLine()) != null;) {
     // process the line.


     System.out.println(line); // check that it's inputted right


     if (replace) {

      line = "*** REPLACED ***";
      replace = false;
     }

     if (line.indexOf("replaceNextLine") > -1) {

      replace = true;
     }


     input2 = input2 += (line + "\n");

    }
    // line is not visible here.
   }






   // check if the new input is right
   System.out.println("----------------------------------" + '\n' + input2);

   //         write the new String with the replaced line OVER the same file
   FileOutputStream fileOut = new FileOutputStream("data.txt");
   fileOut.write(input2.getBytes());
   fileOut.close();

  } catch (Exception e) {
   System.out.println("Problem reading file.");
   e.printStackTrace();
  }
 }

 public static void main(String[] args) {
  replaceSelected("1 adam 20 M", "foobar");
 }
}

如果您运行代码，它将在＆＃34; replaceNextLine＆＃34;：

之后的行之后替换下一行。

$ java FileLineReplace 
asd
zxc
xcv
replaceNextLine
wer
qwe
----------------------------------
asd
zxc
xcv
replaceNextLine
*** REPLACED ***
qwe

我的测试文件是（是）

asd
zxc
xcv
replaceNextLine
wer
qwe

运行程序后，文件看起来像这样，并且替换了指定行之后的行。

asd
zxc
xcv
replaceNextLine
*** REPLACED ***
qwe

Answer 3

可能是这样尝试：读取文件并将每行保留在字符串列表中，如果找到要查找的名称，请替换下一行。然后将该列表中的字符串写回您的文件。示例：

public static void Avreg(SqlCommand command1, string s, string t,
              string p, string c, string d)
{

    var query = "UPDATE....";

    if (c == "0")
    {
        query += ", CitizenshipDate = null";
    }
    else
    {
        query += ", CitizenshipDate = @CitizenshipDate";
        if(!command1.Parameters.Contains("@CitizenshipDate"))
             command1.Parameters.Add("@CitizenshipDate", SqlDbType.NVarChar);
        command1.Parameters["@CitizenshipDate"].Value = string.IsNullOrEmpty(c) ? DBNull.Value : (object)c);
    }
    .....
}

}

txt.txt

public class NewClass {
   public static void main(String[] args) {
      List<String> list = new ArrayList<String>();
      list = readFile("uzochi");
      writeToFile(list);
   }

public static  List<String> readFile(String name){
    List<String> list = new ArrayList<String>();
    try {
        FileReader reader = new FileReader("C:\\users\\uzochi\\desktop\\txt.txt");
        BufferedReader bufferedReader = new BufferedReader(reader);

        String line;
        boolean nameFound = false;

        while ((line = bufferedReader.readLine()) != null) {
            if(line.equalsIgnoreCase(name)){
                nameFound = true;
                System.out.println("searched name: "+line);
            }
                if(nameFound){                        
                    list.add(line);

                    line = bufferedReader.readLine();
                    System.out.println("line to replace: " + line);
                    line = "another string";
                    System.out.println("replaced line: "+line);
                    list.add(line);
                    nameFound = false;
                }
                else{
                    list.add(line);
                }
        }
        reader.close();

    } catch (IOException e) {
        e.printStackTrace();
    }
    return list;
}

public static void writeToFile(List<String> list){
    try {
            FileWriter writer = new FileWriter("C:\\users\\uzochi\\desktop\\txt.txt", false);
            BufferedWriter bufferedWriter = new BufferedWriter(writer);
            for(String s: list){
                bufferedWriter.write(s);
                bufferedWriter.newLine();
            } 

            bufferedWriter.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

写入txt文档java中的特定行

3 个答案: