Alternate coloring of each character of a string with setSpan() not coloring correctly Android?

Question

I'm trying to do an alternate coloring of each character of an input string using SpannableString's setSpan(), but somehow the outputted string is not colored properly.

//ColorLogic.java:
public SpannableString colorString(String myStr)
{
    SpannableString spnStr=new SpannableString(myStr);
    int strLen=myStr.length();
    for(int i=0; i< strLen; i++)
    {
        if (i%2==0)
        {
             Log.v(DTAG, "vow"+myStr.charAt(i));
             spnStr.setSpan(new ForegroundColorSpan(Color.RED), i, i, 0);

        }
        else
        {
            Log.v(DTAG, "cons"+myStr.charAt(i));
            spnStr.setSpan(new ForegroundColorSpan(Color.BLUE), i, i, 0);
        }
    }
    return spnStr;
}

//In my OnCreate of my activity class:
 // Create the text view
 TextView textView = new TextView(this);
 textView.setTextSize(50);

 //Call Color Logic to color each letter individually
 ColorLogic myColorTxt=new ColorLogic();
 SpannableString spnMsg=myColorTxt.colorString(message);
 textView.setText(spnMsg, BufferType.SPANNABLE);
 setContentView(textView);
 }

 output: 
  ![2 letters][1]
   [1]: https://i.stack.imgur.com/rA8TV.png
   ![3 letters][1]
    [1]: https://i.stack.imgur.com/X039z.png

I have noticed that if I simply have :

spnStr.setSpan(new ForegroundColorSpan(Color.RED), 0, 0, 0);

Then ALL the characters of the string is colored red, even though I had specified the start and stop to be the 1st char. I've tried different Spannable flags such as: android.text.Spannable.SPAN_INCLUSIVE_INCLUSIVE , but the same problem still occurs.

Answer 1

You're specifing i for both start and end - this means you're specifying a span of length 0, not a span of length 1. Try this:

spnStr.setSpan(new ForegroundColorSpan(Color.RED), i, i + 1, 0);