java - 尝试读取二进制保存的整数时 readInt() 不起作用

Question

我尝试将一些整数和 double 以二进制格式保存到 txt 文件。我认为数字保存正确，但问题是当我尝试使用 readInt() 读取整数时。例如，当整数的值为 12 时，该整数的程序输出为 208797696，并且具有更多整数的程序总是以 EOF 异常结束。 readDouble() 没有问题，它工作正常。

import java.util.Scanner;
import java.io.*;

public class CandyFruit {

public static void main(String[] args) throws IOException {
    int i;
    int int_sc ;
    double double_sc;
    String string_sc;
    int seek_w = 0; //seek for writing

    String map = ""; 
    Scanner scan = new Scanner(System.in);
    try (RandomAccessFile write = new RandomAccessFile("fgh.txt", "rw")) {

    for (;;) {  
        System.out.println("1 - write int, 2 - write double, 0 - break");
        i = scan.nextInt();
        if (i == 0) break;
        System.out.println("Your choice:");
        if (i == 1) {
            int_sc = scan.nextInt();
            write_int(write, int_sc, seek_w);
            map = map + "1";
            seek_w += 4; //seek growth for int

        }
        else if (i == 2) {
            double_sc = scan.nextDouble();
            write_double(write, double_sc, seek_w);
            map = map + "2"; 
            seek_w += 8; //seek growth for double
        }
    }
    }

    //catch

    try (RandomAccessFile read = new RandomAccessFile("fgh.txt", "rw")) {

        int seek_r = 0;

        for (int o = 0; o < map.length(); o++) {
            char c = map.charAt(o);

            if (c == '1') {
                read_int(read, seek_r);
                seek_r += 4; //seek growth for int

            }
            else if (c == '2') {

                read_double(read, seek_r);
                seek_r += 8; //seek growth for double 
            }


        }
    }

    //catch

}

public static void write_int (RandomAccessFile write, int scanned, int s) throws IOException {
    write.seek(s);
    write.write(scanned);
}

public static void write_double(RandomAccessFile write, double scanned, int s) throws IOException {
    write.seek(s);
    write.writeDouble(scanned);
}

public static void read_int(RandomAccessFile read, int s) throws IOException {
    read.seek(s);
    System.out.println("Int is: "+read.readInt());
}

public static void read_double(RandomAccessFile read, int s) throws IOException {
    read.seek(s);
    System.out.println("Double is: "+read.readDouble());
}

}

Answer 1

您的 write_int 方法使用 RandomAccessFile.write() 进行写入，它将一个字节写入文件。当您使用 readInt() 时，您会读取该单个字节以及其他任意数据的三个字节(因为您没有写入它们)。

您应该在 write_int 中使用 RandomAccessFile.writeInt()。