The key must be an application-specific resource id

The reason you're not able to use setTag(int, Object) is because android require a pre-compiled unique id in the 'int' argument.

Try creating two unique entry in String.xml xml say, "firstname" & "secondname" & use them as below

imageView.setTag(R.string.firstname, "Abhishek");
imageView.setTag(R.string.lastname, "Gondalia");

THIS WILL DO THE JOB...

If you just have 1 setTag in your class, you could use any int, maybe static final declared in the top.

The problem comes when you had 2 or more setTag's with different keys. I mean:

public static final int KEY_1 = 1;
public static final int KEY_2 = 2;
...
setTag(KEY_1, VALUE_1)
setTag(KEY_2, VALUE_2)
...

That scenario is wrong. You then need to add a value file called maybe ids.xml with the following:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <item type="id" name="resourceDrawable" />
    <item type="id" name="imageURI" />
</resources>

Then, in your class, call:

 ...
 setTag(R.id.resourceDrawable, VALUE_1)
 setTag(R.id.imageURI, VALUE_2)
 ...

I'm a little late to the party but I stumbled on this problem myself today and thought I'd give an answer as well. This answer will be a bit of a compilation of the other answers, but with a twist. First of all, the id, as has been pointed out by others, can NOT be a constant defined in your code (such as private static final int MYID = 123) or any other int that you define as a field somewhere.

The id has to be a precompiled unique id, just like the ones you get for strings that you put in values/strings.xml (ie R.string.mystring). Refer to http://developer.android.com/guide/topics/resources/available-resources.html and http://developer.android.com/guide/topics/resources/more-resources.html for more information.

My suggestion is that you create a new file called values/tags.xml and write:

    <resources xmlns:android="http://schemas.android.com/apk/res/android">
      <item name="TAG_ONLINE_ID" type="id"/>
    </resources>

I think it's better to create a separate file instead of putting it in strings.xml as EtienneSky suggested.