asked on

Why is myList.isSelected(i) so slow? Is there a faster way?

Does anyone know how to speed up the following code?

len = myList.countItems();
for(i=0; i < len; i++) {
if (myList.isSelected(i)) {
// ... do something
}
}

The time lag seems to be on checking to see if an item is selected or not.
Whether or not the item is selected in the list doesn't change the lag.

It takes about 1 sec per item. For example, my list has 300 items and the
above code takes about 5 minutes to complete.

Thanks.

msmolyak

What does isSelected() method do? If it's a short method which it should be then it should take much less than 1 sec to execute. Why don't you print the timestamp to figure out how much isSelected takes vs. the if blok itself.

webster030697

The very first thing I'd do is get rid of len

for(int i = 0; i < myList.countItems(); i++)
{ if(myList.isSelected(i))
{ //do stuff
}
}

of course this is not a huge deal, unless this piece of code gets called a lot.

mag062397

ASKER

Comment for msmolyak:

isSelected is a method in the java.awt.List class.

It determines whether an item in the list is selected or not.

The following code takes basiclly no time at all:

len = myList.countItems();
for(i=0; i < len; i++) {
if (i==10) {
System.out.println("Hello");
}
}

So, I don't think it is the if statement.
-----------------------------------------------------------------------
Comment for webster

The len is there to speed things up. It is my understanding the a function call takes longer than resolving the value of a variable.

webster030697

My mistake. I must have been brain dead when I looked at that.

mag062397

ASKER

One solution I came up with is to use getMultipleSelections.

This ran much much faster. It took 2 seconds to loop through 300 items.

However, I still wonder why isSelected runs so slowly.
????

ASKER CERTIFIED SOLUTION

rembo

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