在Android小部件之间实现发布订阅的本机方式是什么？

I have a custom EditText and a TextView in an Activity. The custom EditText traps for key presses and calculates the number of character entered and wants to publish the character count to the TextView. Should I use the java.util.Observable/Observer way? Or is there a more native android method to achive this?I have a custom EditText and a TextView in an A