Learning Android™ Application Programming: A Hands-On Guide to Building Android Applications

Getting Access to the TextView Within the Activity

In this section, you will write Java code inside an activity. You will obtain a TextView view that refers to the hello id that you added earlier in the /res/layout/activity_main.xml.

1. Open MainActivity.java, and add the following code at the bottom of the onCreate() method. This code finds the TextView with the id R.id.hello, which is a generated constant:

Click here to view code image

TextView hello = (TextView) findViewById(R.id.hello);

Note that you must call setContentView before calling findViewByID(). Otherwise, you will receive a runtime error.

2. Eclipse will put a wavy red line under TextView and display a Quick Fix pop-up box saying, “TextView cannot be resolved to a type.” Hover ...