How to Copy Text to Clip Board in Android?

use ClipboardManager

 ClipboardManager clipboard = (ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE); 
 ClipData clip = ClipData.newPlainText(label, text);
 clipboard.setPrimaryClip(clip);

make sure you have imported android.content.ClipboardManager and NOT android.text.ClipboardManager. Latter is deprecated.
Check this link for Further information.