Java写入文件.使用循环

Question

我有一个简单的应用程序,但它会废弃一个文本文件(这只是练习)我还只有3天的Java.问题是在运行程序之前没有错误然后它会抛出异常并停止.谢谢.这是例外:

      java.io.IOException: Stream closed
    at sun.nio.cs.StreamEncoder.ensureOpen(Unknown Source)
    at sun.nio.cs.StreamEncoder.write(Unknown Source)
    at sun.nio.cs.StreamEncoder.write(Unknown Source)
    at java.io.OutputStreamWriter.write(Unknown Source)
    at java.io.Writer.write(Unknown Source)
    at test.main(test.java:18)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at 
     edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:272)

这是代码.

import java.io.FileWriter;
import java.util.Random;
import java.io.IOException;
public class test {
    public static void main(String[] args) throws IOException {

        final String alphabet = "abcdefghigklmnopqrstuvwxyz";
        final int N = alphabet.length();
        Random r = new Random();

        FileWriter file = new FileWriter("hello.txt");
        String sb = " ";
        for (int i = 0; i < 1;) {
            sb += alphabet.charAt(r.nextInt(N));
            System.out.println(sb);
            int length = sb.length();
            file.write(sb);
            file.close();
            if (length == 30) {
                sb = " ";
            }
        }
    }
}

Answer 1

问题是你正在关闭FileWriter并尝试再次使用它.

相反,在完成循环后关闭writer:

try (FileWriter file = new FileWriter("hello.txt")) {
  String sb = " ";
  for (int i = 0; i < 1; i++) {  // Note: added a i++
    sb += alphabet.charAt(r.nextInt(N));
    System.out.println(sb);
    int length = sb.length();
    file.write(sb);
    // file.close();   <---- NOPE: don't do this
    if (length == 30) {
      sb = " ";
    }
  }
}

感谢Andrew发现i++遗漏.