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Java 文件处理完全指南：创建、读取、写入和删除文件详细解析

文件处理是 Java 编程中的一个重要部分，涉及创建、读取、写入和删除文件。下面是一个详细的指南，介绍如何在 Java 中处理文件。

1. 创建文件

Java 提供了 File 类来处理文件和目录。可以使用 File 类的 createNewFile() 方法来创建新文件。

import java.io.File;
import java.io.IOException;

public class CreateFile {
    public static void main(String[] args) {
        try {
            File file = new File("example.txt");
            if (file.createNewFile()) {
                System.out.println("File created: " + file.getName());
            } else {
                System.out.println("File already exists.");
            }
        } catch (IOException e) {
            System.out.println("An error occurred.");
            e.printStackTrace();
        }
    }
}

2. 读取文件

可以使用 Scanner 类或 BufferedReader 类来读取文件内容。

使用 Scanner 类

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class ReadFile {
    public static void main(String[] args) {
        try {
            File file = new File("example.txt");
            Scanner reader = new Scanner(file);
            while (reader.hasNextLine()) {
                String line = reader.nextLine();
                System.out.println(line);
            }
            reader.close();
        } catch (FileNotFoundException e) {
            System.out.println("An error occurred.");
            e.printStackTrace();
        }
    }
}

使用 BufferedReader 类

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

public class ReadFileBuffered {
    public static void main(String[] args) {
        try (BufferedReader reader = new BufferedReader(new FileReader("example.txt"))) {
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
        } catch (IOException e) {
            System.out.println("An error occurred.");
            e.printStackTrace();
        }
    }
}

3. 写入文件

可以使用 FileWriter 类或 BufferedWriter 类来写入文件。

使用 FileWriter 类

import java.io.FileWriter;
import java.io.IOException;

public class WriteFile {
    public static void main(String[] args) {
        try {
            FileWriter writer = new FileWriter("example.txt");
            writer.write("Hello, world!");
            writer.close();
            System.out.println("Successfully wrote to the file.");
        } catch (IOException e) {
            System.out.println("An error occurred.");
            e.printStackTrace();
        }
    }
}

使用 BufferedWriter 类

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

public class WriteFileBuffered {
    public static void main(String[] args) {
        try (BufferedWriter writer = new BufferedWriter(new FileWriter("example.txt"))) {
            writer.write("Hello, world!");
            System.out.println("Successfully wrote to the file.");
        } catch (IOException e) {
            System.out.println("An error occurred.");
            e.printStackTrace();
        }
    }
}

4. 删除文件

可以使用 File 类的 delete() 方法来删除文件。

import java.io.File;

public class DeleteFile {
    public static void main(String[] args) {
        File file = new File("example.txt");
        if (file.delete()) {
            System.out.println("Deleted the file: " + file.getName());
        } else {
            System.out.println("Failed to delete the file.");
        }
    }
}

总结

这些示例展示了如何在 Java 中进行文件的创建、读取、写入和删除操作。通过这些基础操作，可以处理各种文件相关的任务，并结合异常处理机制来处理可能出现的错误。下面是一个综合示例，展示如何在一个程序中执行所有这些操作：

import java.io.*;

public class FileOperations {
    public static void main(String[] args) {
        String filename = "example.txt";

        // 创建文件
        try {
            File file = new File(filename);
            if (file.createNewFile()) {
                System.out.println("File created: " + file.getName());
            } else {
                System.out.println("File already exists.");
            }
        } catch (IOException e) {
            System.out.println("An error occurred during file creation.");
            e.printStackTrace();
        }

        // 写入文件
        try (BufferedWriter writer = new BufferedWriter(new FileWriter(filename))) {
            writer.write("Hello, world!");
            writer.newLine();
            writer.write("Welcome to file operations in Java.");
            System.out.println("Successfully wrote to the file.");
        } catch (IOException e) {
            System.out.println("An error occurred during file writing.");
            e.printStackTrace();
        }

        // 读取文件
        try (BufferedReader reader = new BufferedReader(new FileReader(filename))) {
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
        } catch (IOException e) {
            System.out.println("An error occurred during file reading.");
            e.printStackTrace();
        }

        // 删除文件
        File fileToDelete = new File(filename);
        if (fileToDelete.delete()) {
            System.out.println("Deleted the file: " + fileToDelete.getName());
        } else {
            System.out.println("Failed to delete the file.");
        }
    }
}

通过这个综合示例，可以更好地理解 Java 文件处理的各个方面。

原文链接：codingdict.net

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