英文:
"Cannot find symbol" in Java file operations
问题
import java.util.Random;
import java.util.Scanner;
import java.io.*;
public class Main {
public static void main(String[] args) {
try {
FileInputStream in = null;
FileOutputStream outp = null;
in = new FileInputStream("file.txt");
Random rand = new Random();
int x = rand.nextInt(9);
int guess;
int count = 0;
Scanner input = new Scanner(System.in);
int temp;
char znak;
int i = 0;
while (i < 1000) {
temp = rand.nextInt(94) + 32;
znak = (char) temp;
in.write((int) znak);
i++;
}
i = 0;
in.close();
outp = new FileOutputStream("file.txt");
while (i < 1000) {
znak = (char) outp.read();
System.out.print(znak);
i++;
}
} catch (Exception e) {
System.out.print("Input error");
return;
}
}
}
出现问题的可能原因是令人困惑的文件流使用。在代码的后半部分，你试图从 outp （FileOutputStream类型）中读取数据，但是 FileOutputStream 并没有提供 read() 方法。类似地，在之前的部分，你试图向 in （FileInputStream类型）中写入数据，但是 FileInputStream 也没有提供 write() 方法。
如果你想在文件中写入数据，你应该使用 FileOutputStream，如果你想从文件中读取数据，你应该使用 FileInputStream。此外，注意在读取数据之前，你需要先将数据写入文件。
希望这些解释对你有所帮助。如果你还有其他问题，请随时问我。
英文:
I have the following code:
import java.util.Random;
import java.util.Scanner;
import java.io.*;
public class Main
{
public static void main(String[] args)
{
try
{
FileInputStream in = null;
FileOutputStream outp = null;
in = new FileInputStream("file.txt");
Random rand = new Random();
int x = rand.nextInt(9);
int guess;
int count=0;
Scanner input = new Scanner(System.in);
int temp;
char znak;
int i=0;
while(i<1000)
{
temp=rand.nextInt(94)+32;
znak=(char)temp;
in.write((int)znak);
i++;
}
i=0;
in.close();
outp = new FileOutputStream("file.txt");
while(i<1000)
{
znak = (char)outp.read();
System.out.print(znak);
i++;
}
}
catch(Exception e)
{
System.out.print("Input error");
return;
}
}
}
I apologise for pasting it all in instead of only the relevant parts, but I'm still new to Java and can't pinpoint where exactly the problem lies. When I attempt to compile it, I get the following errors:
Main.java:31: error: cannot find symbol
in.write((int)znak);
^
symbol: method write(int)
location: variable in of type FileInputStream
Main.java:40: error: cannot find symbol
znak = (char)outp.read();
^
symbol: method read()
location: variable outp of type FileOutputStream
What could be causing the problem here? From what I've gathered, these are normally returned when I try to use an undefined variable, but I do define them before.
答案1
得分: 3
InputStream不可写，OutputStream不可读。您希望执行的操作顺序是相反的。
英文:
InputStreams aren't writable, and OutputStreams aren't readable. You have the order of operations you want to do backwards.
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