Variable never used

Question

I've this portion of code:

/**
 * Checks if the provided URL is valid.
 *
 * @param urlToCheck - The URL to check.
 *
 * @return boolean true if it's valid.
 */
protected boolean isUrlValid( String urlToCheck )
{
    boolean isValid = true;
    try
    {
        URL url = new URL( urlToCheck );
    }
    catch ( MalformedURLException exception )
    {
        isValid = false;
    }

    return isValid;
}

As you can see, I'm creating a new URL Object, which crashes if the String URL is not valid. This is working, the "problem" is that LINT says I'm not using url variable. I don't really have to use it, so here's my question:

Is there any other better approach?
Can I supress lint checking JUST for this line?

You are declaring and initializing the URL in try block, and in the scope of try block, url is never used. So this warning stays.. If you don't want to use url then simply remove that line. — Himanshu Joshi, Nov 06 '13 at 12:11
How about; http://stackoverflow.com/questions/2230676/how-to-check-for-a-valid-url-in-java. Incidently using exceptions for code flow is always a bad idea — Richard Tingle, Nov 06 '13 at 12:11

score 5 · Accepted Answer · answered Nov 06 '13 at 12:11

You see a warning because you are not using the variable and probably wasting memory. If you dont need the variable you can do something like this

protected boolean isUrlValid( String urlToCheck )
{
    boolean isValid = true;
    try
    {
        new URL( urlToCheck ); // Notice this
    }
    catch ( MalformedURLException exception )
    {
        isValid = false;
    }

    return isValid;
}

score 4 · Answer 2 · answered Nov 06 '13 at 12:11

4

There's nothing wrong about doing that, however your variable is not used.

You can change

URL url = new URL( urlToCheck );

to

new URL( urlToCheck );

answered Nov 06 '13 at 12:11

Eel Lee

3,513
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Ankur Shanbhag · Answer 3 · 2013-11-06T12:27:56.623

1

You can replace

URL url = new URL( urlToCheck );

with something like this:

new URL( urlToCheck );

This will ensure that you do not have any unused reference pointing to the URL object. Thus the compiler will not complain.

edited Nov 06 '13 at 12:27

answered Nov 06 '13 at 12:11

Ankur Shanbhag

7,746
2
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38

score 0 · Answer 4 · answered Nov 06 '13 at 14:33

In reverse order:

You can get rid of the warning by not creating a new variable, as others have pointed (use only new Url(urlToCheck);

but maybe the better aproach is to:

use URLUtil.isValidUrl(String url) - looking at it's source I see it doesn't create a new url variable which might be better, but it looks like it just checks whether the string starts with a known scheme. It's up to you to decide whether this is enough

Variable never used

4 Answers4