Re: Read file
Anabolik wrote:
I try to read the content of file text.txt. The size of this file is
26 Mb. And always I have the error:
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:2882)
at java.lang.AbstractStringBuilder.expandCapacity
(AbstractStringBuilder.java:100)
at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:
390)
at java.lang.StringBuffer.append(StringBuffer.java:224)
at lines contents.append(text).append(System.getProperty
("line.separator"));
In addition to what others have said, you can use memory more efficiently.
Preallocate the size of the 'contents' object; right now, it has to copy
itself to a larger buffer every time it grows to accomodate more text. You
know you have a 26 MB file but you initially allocate only 16 characters.
Also, use 'StringBuilder' unless you truly need the thread safety of
'StringBuffer'. It doesn't look like you do.
There are other minor ways to improve your code on which I'll comment in line.
How can I read and save the content of file. The content of file I
need then in the program to show it in some dialog.
You're going to show 26 MB in a dialog?
public static void main(String[] args) {
File file = new File("D:\\work\\text.txt");
StringBuffer contents = new StringBuffer(); // StringBuilder
BufferedReader reader = null;
An alternative is to initialize 'reader' in a separate 'try' block so you
don't have to check for 'null' in the later 'finally'. This is just a matter
of style.
try {
reader = new BufferedReader(new FileReader(file));
String text = null;
OTOH, this 'null' initialization is truly redundant. And unnecessary.
Superfluous, even. Plus the scope of 'text' is wider than it need be.
// repeat until all lines is read
This comment doesn't add any clarity or explanation.
while ((text = reader.readLine()) != null)
An alternative idiom that limits the scope of 'text':
for ( String text; (text = reader.readLine()) != null; )
{
contents.append(text).append(System.getProperty
("line.separator"));
Since it's unlikely that this system property will change during the loop, you
could define a variable outside the loop to hold it.
}
} catch (FileNotFoundException e)
{
e.printStackTrace();
} catch (IOException e)
{
e.printStackTrace();
} finally
{
try
{
if (reader != null)
{
reader.close();
}
} catch (IOException e)
{
e.printStackTrace();
}
}
// show file contents here
System.out.println(contents.toString());
}
--
Lew