Java 使用finally关闭流

我是Java新手，刚刚学到应该在try/catch/finally块中关闭流，但这迫使我在finally包装中使用另一个try-catch，否则我必须抛出异常

这段代码来自一个练习，我不仅要通过它，还要建立良好的编码实践。请告诉我关门的时间好吗？请随意批评代码的其他方面并将其撕碎。这是我好转的唯一途径

/* 
Read 2 file names from the console: file1, file2.
Write all the bytes in file1 to file2, but in the reverse order.
Close the streams.

Requirements:
1. The program should read a file name twice from the console.
2. Use FileInputStream to read from a file, and use FileOutputStream to write to a file.
3. In the second file, you need to write all the bytes from the first file in the reverse order.
4. The FileInputStream and FileOutputStream must be closed.

*/

import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;

public class Solution {

    private void copyArray () {
        FileInputStream input = null;
        FileOutputStream output = null;

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            System.out.print("Enter a filename to be read: ");
            String file1 = reader.readLine();
            System.out.print("Enter a filename to write to: ");
            String file2 = reader.readLine();

            input = new FileInputStream(file1);
            output = new FileOutputStream(file2);

            byte[] buffer = new byte[input.available()];

            int count = input.available();
            input.read(buffer);
            for (int i = count-1; i>=0; i--) {
                output.write(buffer[i]);
            }
        } catch (IOException e) {
            System.out.println("General I/O exception: " + e.getMessage());
        } finally {
            try {
                input.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

            try {
                output.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) throws IOException {
          new Solution().copyArray();
    }
}

---

您可以使用try with资源

try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))){

        System.out.print("Enter a filename to be read: ");
        String file1 = reader.readLine();
        System.out.print("Enter a filename to write to: ");
        String file2 = reader.readLine();

        try(FileInputStream input = new FileInputStream(file1);FileOutputStream  output = new FileOutputStream(file2)){
            byte[] buffer = new byte[input.available()];

            int count = input.available();
            input.read(buffer);
            for (int i = count-1; i>=0; i--) {
                output.write(buffer[i]);
            }
        }

    } catch (IOException e) {
        System.out.println("General I/O exception: " + e.getMessage());
    }

在发布任何问题之前，请仔细阅读指南。 无论如何，我相信，这将是使用Java特性的正确方法-

尝试使用资源

private static void copyArray () {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter a filename to be read: ");
        String file1 = scanner.next();
        System.out.print("Enter a filename to write to: ");
        String file2 = scanner.next();
        scanner.close();
        try (FileInputStream input = new FileInputStream(new File(file1)) ; 
             FileOutputStream output = new FileOutputStream(new File(file2))){

            byte[] buffer = new byte[input.available()];

            int count = input.available();
            input.read(buffer);
            for (int i = count-1; i>=0; i--) {
                output.write(buffer[i]);
            }
        } catch (IOException e) {
            System.out.println("General I/O exception: " + e.getMessage());
        }
 }

---

如果代码正常工作，并且您希望对其进行改进而不是解决问题，那么这个问题可能更适合。您应该使用。您的学习或教学已经过时几年了。注意：这是对

available（）

的滥用。请参阅Javadoc。两次调用它只是要求它在第一次调用和第二次调用之间增加，这将导致代码失败。您还应该对

BufferedReader

使用

try with resources

。是的，我会更新我的答案。