java - 如何从java中读取字节数组中的数据

Question

我将 mp3 文件转换为字节数组，并从字节数组中读取，但它在第 15 行显示空指针异常我的代码:

public class MainClass {
    static byte[] bytesarray = null;

    public static void main(String args[]) {
        try {
            FileInputStream fis = new FileInputStream("D:\\taxi.mp3");
            try {
                fis.read(bytesarray, 0, 32);
                System.out.println(bytesarray.length);
            } catch (IOException e) {
                e.printStackTrace();
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        ByteArrayInputStream in = new ByteArrayInputStream(bytesarray);
        for (int i = 0; i < 32; i++) {
            int c;
            while ((c = in.read()) != -1) {
                if (i == 0) {
                    System.out.print((char) c);
                } else {
                    System.out.print(Character.toUpperCase((char) c));
                }
            }
            System.out.println();

        }
    }
}

Answer 1

static byte[] bytesarray = new byte[32]; 应该可以完成工作，您没有初始化数组...

请参阅documentation of read .