Question

When i try to create a textview and link it to a XML component in my application my app seems to crash. the code i am using is:

public class WorkoutAdvice extends Activity {
TextView adviceshow;
@Override
public void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    String[] advice = getResources().getStringArray(R.array.races_array);
    Random rand = new Random(); 
    int ad = rand.nextInt(5);
    String gen = advice[ad];
    adviceshow = (TextView)findViewById(R.id.advice);
    adviceshow.setText(gen);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.advice);       

}
}

and the logcat for when my application closes is

05-26 01:43:23.018: E/AndroidRuntime(363): FATAL EXCEPTION: main
05-26 01:43:23.018: E/AndroidRuntime(363): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.b00348312.workout/com.b00348312.workout.WorkoutAdvice}: java.lang.NullPointerException
05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
05-26 01:43:23.018: E/AndroidRuntime(363): at android.os.Handler.dispatchMessage(Handler.java:99)
05-26 01:43:23.018: E/AndroidRuntime(363): at android.os.Looper.loop(Looper.java:123)
05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread.main(ActivityThread.java:4627)
05-26 01:43:23.018: E/AndroidRuntime(363): at java.lang.reflect.Method.invokeNative(Native Method)
05-26 01:43:23.018: E/AndroidRuntime(363): at java.lang.reflect.Method.invoke(Method.java:521)
05-26 01:43:23.018: E/AndroidRuntime(363): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
05-26 01:43:23.018: E/AndroidRuntime(363): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
05-26 01:43:23.018: E/AndroidRuntime(363): at dalvik.system.NativeStart.main(Native Method)
05-26 01:43:23.018: E/AndroidRuntime(363): Caused by: java.lang.NullPointerException
05-26 01:43:23.018: E/AndroidRuntime(363): at com.b00348312.workout.WorkoutAdvice.onCreate(WorkoutAdvice.java:22)
05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
05-26 01:43:23.018: E/AndroidRuntime(363): … 11 more

the application works without the statements dealing with the findbyID lines which work in other parts of the application

Answer 1

Until you actually set your activity content by calling setContentView, there are no views to be found. Once you have called setContentView, then you may try to find your TextView. Note that before this call, the Activity has no knowledge at all of which(s) XML layouts will it be binded to (if any).