Thanks for the feedback.. Now I'm trying to use StringBuilder and
Formatter, but I just can't get it to stop doing the garbage
collection. I'm not sure how to go about reusing the Formatter. At
first, I just tried creating a public static Formatter member variable
and using it directly:
public Formatter mFormatter = new Formatter();
(then later within setViewValue()... )
mFormatter.format("%.2f",pricef).toString();
Unfortunately the formatter seemed to keep "building" onto itself,
making each item in the list return a longer and longer string as I
scrolled.
Then I looked into the Android source code and found an example that I
tried to mimick. While it gives me the output I expect, it hasn't
improved my garbage collection problem. I'm just going to post the
majority of my ViewBinder class, can someone point out where I'm going
wrong?
<START CODE>
import java.util.Formatter;
import android.database.Cursor;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;
import android.widget.ImageView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
public class ItemBinder implements SimpleCursorAdapter.ViewBinder {
public static final StringBuilder mBuilder = new StringBuilder();
public static final Formatter mFormatter = new Formatter(mBuilder);
public static final Object[] mArgs = new Object[1];
public boolean setViewValue(View view, Cursor cursor, int
columnIndex) {
switch(view.getId()) {
case R.id.price:
// Format the price nicely
String price = cursor.getString(columnIndex);
final float pricef = Float.parseFloat(price);
Object[] args = mArgs;
args[0] = pricef;
mBuilder.setLength(0);
price = mFormatter.format("%.2f", args).toString();
((TextView)view).setText(price);
return true;
}
return false;
}
}
<END CODE>
On Apr 13, 10:40 pm, Marco Nelissen <[email protected]> wrote:
> Don't use String.format(). It creates all kinds of temporary objects
> every time you call it.
> Instead, create a single StringBuilder and Formatter, and then reuse
> those every time you need to format a string.
>
> On Mon, Apr 13, 2009 at 7:37 PM, DavidG <[email protected]> wrote:
>
> > In my ListView, there's one line of code in my ViewBinder that causes
> > lots of garbage collection as I scroll through the list, about every
> > two seconds...
>
> > D/dalvikvm(16312): GC freed 13171 objects / 659576 bytes in 162ms
> > D/dalvikvm(16312): GC freed 13122 objects / 654128 bytes in 129ms
> > D/dalvikvm(16312): GC freed 13134 objects / 655416 bytes in 142ms
> > D/dalvikvm(16312): GC freed 13129 objects / 654840 bytes in 129ms
> > D/dalvikvm(16312): GC freed 13149 objects / 655000 bytes in 110ms
> > D/dalvikvm(16312): GC freed 13150 objects / 655720 bytes in 127ms
> > D/dalvikvm(16312): GC freed 13075 objects / 652256 bytes in 111ms
> > D/dalvikvm(16312): GC freed 13232 objects / 659040 bytes in 136ms
> > D/dalvikvm(16312): GC freed 13106 objects / 653920 bytes in 110ms
> > D/dalvikvm(16312): GC freed 13155 objects / 655152 bytes in 110ms
>
> > The offending code is here, which formats a price for each item in the
> > list:
>
> > String price = cursor.getString(columnIndex);
> > final float pricef = Float.parseFloat(price);
> > price = new StringBuffer("$").append(String.format("%.
> > 2f",pricef)).toString();
> > ((TextView)view).setText(price);
>
> > If I comment out the line with String.format, the garbage collection
> > goes away. So what's the "right" way to do this to avoid allocations?
> > That database field holds an unformatted text string which I'm trying
> > to format into proper currency format (example: format "1.5" to
> > "$1.50")
>
> > Any pointers on how to improve this?
>
>
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