Closing IO Streams

[ZOCOR]

Hi

Consider:

try
{
FileReader fr = new FileReader("file.txt");
BufferedReader br = new BufferedReader(fr);
doSomething();
br.close();
}
catch (IOException e)
{
e.printStackTrace();
}

Questions:

1. Do i also need to close FileReader fr by doing fr.close?
2. if I want to parse a new file, do i just make fr point to a new object
say fr = new FileReader("file2.txt")? or start over again?

Thanks in advance

ZOCOR

 

[Carlo Pellegrini]

Hi

Consider:

try
{
FileReader fr = new FileReader("file.txt");
BufferedReader br = new BufferedReader(fr);
doSomething();
br.close();
}
catch (IOException e)
{
e.printStackTrace();
}

Questions:

1. Do i also need to close FileReader fr by doing fr.close?

No, the underlying stream is closea as well.

2. if I want to parse a new file, do i just make fr point to a new object
say fr = new FileReader("file2.txt")? or start over again?

No, you must start over again. The variable br holds a reference of the old
FileReader.

CarloP.

 

[ZOCOR]

No, the underlying stream is closea as well.


No, you must start over again. The variable br holds a reference of the old
FileReader.

But the old FileReader now points to something else:

fr = new FileReader("file2.txt");

br holds a reference to fr and fr is now something different, so it should
work right?


ZOCOR

 

[Michael Borgwardt]

However, the close() call should happen in a finally
block after the catch, otherwise, the stream will
remain open if an exception is thrown.

But the old FileReader now points to something else:

fr = new FileReader("file2.txt");

No, it is the variable that has the name "fr" in your code
that holds a reference which points at a new object.

br holds a reference to fr

No, the object at which the reference in br points holds a copy of the value
of fr at the time the br object was created, i.e. a reference to the object
fr pointed at at that time. That reference does not change, no matter what
you do.