Use SpannableString and ImageSpan to achieve this.
String msg=" "+"haii";
ImageSpan mImageSpan== new ImageSpan(mContext, R.drawable.icon);
SpannableString text = new SpannableString(msg);
text.setSpan(mImageSpan, 0, 1, 0);
mTextView.setText(text);
the extra space in the string variable is replaced by the icon.