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Core Java Technologies Tech Tips Quiz

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Quizzes Index

by Ed Ort

October 2002

Test your knowledge of Java programming language topics covered in some recent Core Java Technologies Tech Tips (formerly, JDC Tech Tips), an electronic mailing containing tips, techniques, and sample code on various topics of interest to developers using the Java platform.

Which of the following timer classes schedules tasks for execution in a background thread?

A. javax.swing.Timer

B. java.util.Timer

Why should you specify the -source 1.4 flag when you compile the following program?

public class AssertDemo {
   public static void main(String args[]) {
      boolean enabled = false;
                         
      assert enabled = true;
                         
      System.out.println("Assertions are " +
         (enabled ? "enabled" : "disabled"));
   }
}

A.	The compiler will recognize `assert` as a keyword.
B.	The compiler will enable an assertion trace.
C.	The compiler will mark assertions for removal if the program is run in a resource constrained device.
D.	The program will run faster.

Is a zero-length array valid in the Java programming language?

A. Yes

B. No

What is a regular expression?

A.	An algorithm that evaluates a regular value.
B.	An expression that does not include special variables or operators.
C.	An expression that is used recursively.
D.	A pattern of characters that is often used in pattern matching.

How do you display text in multiple colors or styles in a JTextArea component?

A.	Use setter methods, such as `setSelectedTextColor` to set multiple colors or styles in the `JTextArea` component.
B.	Use the `createDefaultModel` method to create a default model that provides for multiple styles and colors in the `JTextArea` component.
C.	Specify an attribute set for the `JTextArea` component.
D.	You can't display multiple colors or styles in a JTextArea component.

What does the following program display?

public class OverDemo1 {         
    // overload methodA between short/int
                         
    static void methodA(short s) {
    System.out.println(
         "methodA(short) called");
    }
    static void methodA(int i) {
    System.out.println("methodA(int) called");
    }
                         
    // overload methodB between float/double
                         
    static void methodB(float f) {
    System.out.println(
         "methodB(float) called");
    }
    static void methodB(double d) {
    System.out.println(
         "methodB(double) called");
    }
                         
    public static void main(String args[]) {
                         
    // call methodA with char argument
                         
    methodA('a');
                         
    // call methodB with int argument
                         
    methodB(Integer.MAX_VALUE);
    }
}

A.	methodB(float) called methodA(int) called
B	methodA(short) called methodB(double) called
C.	methodA(int) called methodB(float) called
D	methodB(double) called methodA(int) called

What Java API implements Porter-Duff rules?

A. Java Media Framework (JMF)

B. Java 2D

C. Java 3D

D. None of the above
Is it possible to programmatically access the individual elements of a stack traceback?

A. Yes

B. No

Why is it often a good idea to provide a readResolve method for a serializable class?

A.	The method improves serialization/deserialization efficiency
B.	It's mandatory when serializing/deserializing instance-controlled classes
C.	You can implement the method to resolve anomalies resulting from deserialization
D.	All of the above

Which of the following methods return the symbol for a currency?

A. java.math.Currency.getSymbol

B. java.util.Currency.getSymbol

C. java.lang.Object.getSymbol

D. java.util.Locale.getSymbol

¹ As used on this web site, the terms "Java virtual machine" or "JVM" mean a virtual machine for the Java platform.


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