Java in 21 Days (8th Edition) Day 10: Building an Interface

Notes and Corrections

View the Certification Practice quiz solution
Certification answer: Answer (c) is correct. A call to super(), the constructor of a superclass, must always be the first line in a constructor. The compiler fails and displays the message "call to super() must be first statement in constructor."
Answer (b) is incorrect because the source code does not compile. However, it is true that nothing is displayed in the frame[md]the slider component was never added to the frame.
Answer (a) is incorrect because the source code does not compile and does not run successfully[md]the frame is displayed but nothing is shown in the frame. The slider component was never added to the frame.
Answer (d) is incorrect because the call to add() is correct.