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I have a condition that a StringBuilder keeps storing lines matching a pattern from a large flat file (100's of MB). However after reaching a condition I write the content of the StringBuilder varialble to a textfile.
Now I wonder if I should use the same variable by resetting the object ->
stringBuilder.delete(0,stringBuilder.length()) OR
stringBuilder=new StringBuilder(); Please suggest which would do you think is better as far as both performance and OOM issues are concerned.
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Using setLength() method A simple solution to clear a StringBuilder / StringBuffer in Java is calling the setLength(0) method on its instance, which causes its length to change to 0. The setLength() method fills the array used for character storage with zeros and sets the count of characters used to the given length.
StringBuilder will only create a new string when toString() is called on it. Until then, it keeps an char[] array of all the elements added to it. Any operation you perform, like insert or reverse is performed on that array.
Clear Method is used to remove all the characters from the current StringBuilder instance.
No, a StringBuilder is a purely managed resource. You should just get rid of all references to it.
I think StringBuilder#delete(start, end) is still expensive call, you should do:
stringBuilder.setLength(0); to reset it.
UPDATE: After looking at source code of StringBuilder It seems setLength(int) leaves old buffer intact and it is better to call: StringBuilder#trimToSize() after above call which attempts to reduce storage used for the character sequence.
So something like this would be more efficient:
stringBuilder.setLength(0); // set length of buffer to 0 stringBuilder.trimToSize(); // trim the underlying buffer If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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