Re: Copy files in java gives me out of memory error

Daniel Pitts <>
Tue, 25 Dec 2007 09:33:01 -0800
Canned wrote:

I'm trying to create a class which only jobs is to copy any text files
before its get opened by text editor. I build a constructor that will
read from file then store its content in textContent variable. From
there, copy method would read from textContent and write its content in
a new file. But instead of doing its job, I get "Exception in thread
"main" java.lang.OutOfMemoryError: Java heap space
    at java.util.Arrays.copyOf(
    at java.lang.AbstractStringBuilder.append(
    at java.lang.StringBuilder.append(
    at v1.CreateBackup.<init>(
    at v1.EditorSWT.openFileDialog(
    at v1.EditorSWT.access$0(
    at v1.EditorSWT$1.widgetSelected(
    at org.eclipse.swt.widgets.TypedListener.handleEvent(Unknown Source)
    at org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
    at org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
    at v1.EditorSWT.main(
Can someone please tell me what I'm doing wrong? I'm not very
experienced in Java

Quite simple, you're reading entire files into memory. More
specifically, you're reading the file into a StringBuilder. Don't do

Use a FileInputStream, and a FileOutputStream, and copy a small amount
at a time (say 8k) using a byte array.
Daniel Pitts' Tech Blog: <>

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