Cannot refer to a non-final variable l inside an inner class defined in a different method

Question

I'm trying to set an OnClickListener to some elements in my Android app, these elements are dynamically defined and are not given ids, but they are put in a LinearLayouts which exists in an List of LinearLayouts, so I set the OnClickListener as follows:

    List<LinearLayout> inner_ver = setElemets(1);

       for (LinearLayout l: inner_ver){
                l.getChildAt(0).setOnClickListener(new OnClickListener() { // here's the syntax error
                @Override
                public void onClick(View v) {
                    l.getChildAt(1).setBackgroundResource(R.drawable.home_curtopen);
                }
            });
        }

but I got the syntax error mentioned in the title with l and I can't just declare it as final cause then it assigns the changes only to the last element in the List.

score 4 · Accepted Answer · answered Jan 12 '14 at 14:02

4

Split into a separate method:

    for (LinearLayout l: inner_ver){
        assignListener(l);
    }

public void assignListener(final LinearLayout l) {
    l.getChildAt(0).setOnClickListener(new View.OnClickListener() { 
        @Override
        public void onClick(View v) {
            l.getChildAt(1).setBackgroundResource(R.drawable.home_curtopen);
        }
    });
}

answered Jan 12 '14 at 14:02

Greg Ennis

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it's also just deals with the last Layout in the List – MRefaat Jan 12 '14 at 14:16
That doesnt seem right. Is it possible you have an error elsewhere in your code? The layout L is scoped to every iteration in the loop seperately. – Greg Ennis Jan 12 '14 at 14:23
you are right, i had also another error but after correcting it your way worked fine with me – MRefaat Jan 14 '14 at 09:24

score 3 · Answer 2 · answered Jan 12 '14 at 14:07

You could also create your own OnClickListener class:

class MyOnClickListener implements OnClickListener{
    private LinearLayout layout;

    public MyOnClickListener(LinearLayout layout){
        this.layout = layout;
    }

    @Override
    public void onClick(View v) {
        layout.getChildAt(1).setBackgroundResource(R.drawable.home_curtopen);
    }

}

Then change your loop to:

for (LinearLayout l: inner_ver){
    l.getChildAt(0).setOnClickListener(new MyOnClickListener(l));
}

your way worked also , i just voted it up and choose the "oldest" right answer — MRefaat, Jan 14 '14 at 09:25

score 1 · Answer 3 · edited May 23 '17 at 12:13

1

You could add final to your for loop

List<LinearLayout> inner_ver = setElemets(1);

   for (final LinearLayout l: inner_ver){
            l.getChildAt(0).setOnClickListener(new OnClickListener() { // here's the syntax error
            @Override
            public void onClick(View v) {
                l.getChildAt(1).setBackgroundResource(R.drawable.home_curtopen);
            }
        });
    }

Why for(final Type name : Iterable) works is explained in

How does "final int i" work inside of a Java for loop?

edited May 23 '17 at 12:13

Community

1
1

answered Jan 12 '14 at 14:24

zapl

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He said this still only assigned click to the final loop iteration, but given he didn't like my answer either, I think yours is correct and he has a logic error elsewhere in his code. – Greg Ennis Jan 12 '14 at 14:37
@GregEnnis most likely. `l.getChildAt(0)` could simply be the same thing all the time. – zapl Jan 12 '14 at 14:40
you point is right too ,but i just voted it up and choose the "oldest" right answer as an accepted answer – MRefaat Jan 14 '14 at 09:27
1

@MRefaat That's fine. The one you accepted is also a bit cleaner in style since it increases legibility. – zapl Jan 14 '14 at 11:30

Cannot refer to a non-final variable l inside an inner class defined in a different method

3 Answers3