How to specify null value for a string resource in xml in Android?

Question

In my values.xml, I have some string resources. But sometimes, I want to have a null value for that string resource for specific reasons.

How do I specify that string to have a null value?

values.xml:

<string name="default_item_0">Some String</string>
<string name="default_item_1">@null</string>

Java code:

String item0 = context.getString(R.string.default_item_0);
String item1 = context.getString(R.string.default_item_1);

Expected:

String item0 = "Some String";
String item1 = null;

Actual:

String item0 = "Some String";
String item1 = "@0";

I tried the @null value, but it returns a string of @0 instead.

Is it possible to have a null value in xml?

@PolyBug very interesting question :) Sorry though I dont have any answer for that :| I'll look forward for the solution as well :) — Sandeep Bhandari, Apr 11 '16 at 06:21
`if(getResources().getString(R.string.default_item_1).matches("@null")){}` — IntelliJ Amiya, Apr 11 '16 at 06:22
you can use @IntelliJAmiya idea. or you can set your resource to %s then String.format(your_resource,null); — Randyka Yudhistira, Apr 11 '16 at 06:23
I really don't think its a good idea but if you really want to how about not declaring it in the first place but trying to use it? of course you can't context.getString(null) and expect to not get a null pointer error — Pomagranite, Apr 11 '16 at 06:29
@IntelliJAmiya Unfortunately, no solution is available. Technically, xml doesn't have values for `@null`. — Poly Bug, Jan 12 '17 at 01:10

Farshad · Answer 1 · 2017-04-29T19:41:53.803

As you know resources exist because they're supposed to be "something NOT null", and @null is simply a reference resource with a zero-value id.

Is it possible to have a null value in xml?

Null value for string resources? No and honestly it doesn't seem reasonable

But in this case with your specific reasons I suggest you to add an empty string to resources:

<string name="empty"/>

Then you can check if it is empty or not :

String str = getString(R.string.empty);
    if (TextUtils.isEmpty(str)) {
        //do something
    }

P.S: Earlier I used this approach to map indices to the correct items of an array, as you guess in my case some indices were skipped so I had to skip some array items as well.

score 0 · Answer 2 · edited May 23 '17 at 12:26

0

You can try with matches

Tests whether this string matches the given regularExpression. This method returns true only if the regular expression matches the entire input string.

if(getResources().getString(R.string.default_item_1).matches("@null")) 
{ 
     // Your logic
}
else
    {
     // Your logic
    }

If you need to format your strings using String.format(String, Object...), then you can do so by putting your format arguments in the string resource.

Courtesy dynamic String using String.xml?

edited May 23 '17 at 12:26

Community

1
1

answered Apr 11 '16 at 06:25

IntelliJ Amiya

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I consider this as a workaround solution. I'd have to remember if a particular string resource can have null values, logically speaking, which will be a hassle. I hope there's a direct method for assigning nulls via xml. – Poly Bug Apr 11 '16 at 06:35
@PolyBug Indeed indeed . Did you get any another solutions ? – IntelliJ Amiya Apr 11 '16 at 10:09
1

None so far. There isn't any constant R definition of a null value defined in android. – Poly Bug Apr 11 '16 at 15:16

score -1 · Answer 3 · answered Apr 11 '16 at 06:34

You can use method for this.

 public static boolean isNullString(String string) {
    try {
        if (string.trim().equalsIgnoreCase("null") || string.trim() == null || string.trim().length() < 0 || string.trim().equals("")) {
            return true;
        } else {
            return false;
        }
    } catch (Exception e) {
        return true;
    }
}

Use this method as

if(isNullStrind(your string value){
//true
write your code
}else{
//false
}

How to specify null value for a string resource in xml in Android?

3 Answers3