如何修改文本文件？

with open('file.txt', 'r') as file:
    content = file.read()

# 修改内容
content = content.replace('old_text', 'new_text')

with open('file.txt', 'w') as file:
    file.write(content)

const fs = require('fs');

fs.readFile('file.txt', 'utf8', (err, data) => {
    if (err) throw err;

    // 修改内容
    const content = data.replace('old_text', 'new_text');

    fs.writeFile('file.txt', content, 'utf8', (err) => {
        if (err) throw err;
    });
});

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class Main {
    public static void main(String[] args) {
        try {
            BufferedReader reader = new BufferedReader(new FileReader("file.txt"));
            String line;
            StringBuilder content = new StringBuilder();

            while ((line = reader.readLine()) != null) {
                content.append(line).append("\n");
            }

            reader.close();

            // 修改内容
            String newContent = content.toString().replace("old_text", "new_text");

            BufferedWriter writer = new BufferedWriter(new FileWriter("file.txt"));
            writer.write(newContent);
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}