Name: bb33257 Date: 06/27/98


The following program creates a PrintWriter based on ByteArrayOutputStream, and
then closes the underlying stream. Even though the byte stream is closed, I can
print to the PrintWriter without receiving an error.

This problem causes a JCK test to fail.
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import java.io.*;
public class PWTest {
  public static void main(String[] args) throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    OutputStreamWriter osw = new OutputStreamWriter(baos);
    PrintWriter pw = new PrintWriter(osw);
    baos.close();
    pw.print("foo");
    System.out.println("Should get checkError = true.");
    System.out.println("Did get checkError = " +pw.checkError());
  }
}
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The resulting output is:

Should get checkError = true.
Did get checkError = false
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Reopened with a comment:

If the write cannot succeed because the destination stream is closed, why would you not treat that as an error?

Here's an interesting fact: in the test case above, if I close the OutputStreamWriter, and then write to it, the checkError is true. If I close the ByteArrayOutputStream and attempt a write, the checkError is false. So this is inconsistent API behavior.

I also tried opening, writing to, closing and then writing again to a ByteArrayOutputStream directly (with no wrappers). I find that ByteArrayOutputStream does not throw an exception when you try to operate on it in the closed state. So perhaps this (invalid) behavior is propagating upwards?