在不截断文件的情况下读取文件，如果文件不存在，则创建文件

# 读取文件
try:
    file = open("file.txt", "r")
    content = file.read()
    file.close()
    print(content)
except FileNotFoundError:
    print("文件不存在")

# 创建文件并写入内容
file = open("file.txt", "w")
file.write("初始化内容")
file.close()

# 重新读取文件
file = open("file.txt", "r")
content = file.read()
file.close()
print(content)

import java.io.*;

public class FileExample {
    public static void main(String[] args) {
        File file = new File("file.txt");

        // 读取文件
        try {
            BufferedReader reader = new BufferedReader(new FileReader(file));
            String line = reader.readLine();
            reader.close();
            System.out.println(line);
        } catch (FileNotFoundException e) {
            System.out.println("文件不存在");
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 创建文件并写入内容
        try {
            BufferedWriter writer = new BufferedWriter(new FileWriter(file));
            writer.write("初始化内容");
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 重新读取文件
        try {
            BufferedReader reader = new BufferedReader(new FileReader(file));
            String line = reader.readLine();
            reader.close();
            System.out.println(line);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}