Exam 10: Interfaces

Consider the following declarations: public interface Measurer { Int measure(Object anObject); } Public class StringLengthMeasurer implements Measurer { Public int measure(_________________) { String str = (String) anObject; Return str.length(); } } What parameter declaration can be used to complete the callback measure method?

A/an ____ belongs to a class whose methods describe the actions to be taken when a user clicks a user-interface graphical object.

You wish to implement a callback method for an object created from a system class that you cannot change. What approach does the textbook recommend to accomplish this?

Consider the following code snippet: final RectangleComponent component = new RectangleComponent(); MouseListener listener = new MousePressListener(); Component.addMouseListener(listener); ______________ Frame.add(component); Frame.setSize(FRAME_WIDTH, FRAME_HEIGHT); Frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); Frame.setVisible(true); Which of the following statements completes this code?

Which of the following statements about an inner class is true?

An inner class can access local variables from the enclosing scope only if they are declared as ____.

A/an ____ class defined in a method signals to the reader of your program that the class is not interesting beyond the scope of the method.

When you use a timer, you need to define a class that implements the ____ interface.

Suppose listener is an instance of a class that implements the MouseListener interface. How many methods does listener have?

Which of the following statements about abstract methods is true?

A(n) ____ has an instance method addActionListener() for specifying which object is responsible for implementing the action associated with the object.

____ methods must be implemented when using an interface.

Consider the following code snippet: class MyListener implements ActionListener { Public void actionPerformed(ActionEvent event) { System.out.println(event); } } Timer t = new Timer(interval, listener); t.start(); What is wrong with this code?

Which of the following statements about an inner class is true?

Assuming that interface Resizable is declared elsewhere, consider the following class declaration: public class InnerClassExample { Public static void main(String[] args) { Class SizeModifier implements Resizable { // class methods } __________________________ // missing statement } } Which of the following declarations can be used to complete the main method?

When an event occurs, the event source notifies all ____.

Consider the following code snippet: public interface Sizable { Int LARGE_CHANGE = 100; Int SMALL_CHANGE = 20; Void changeSize(); } Which of the following statements is true?

Event listeners are often installed as ____ classes so that they can have access to the surrounding fields, methods, and final variables.

The Timer class is found in the ____ package.

The method below is designed to print the smaller of two values received as arguments. Select the correct expression to complete the method. public void showSmaller(Comparable value1, Comparable value2) { If ( _________________________ ) System.out.println(value1 + " is smaller."); Else System.out.println(value2 + " is smaller."); }