Technology problems
- 1. What is difference between Path and Classpath? Discuss
Correct Answer: PATH and CLASSPATH are operating system level environment variables PATH is used to define where the system can find the executables (exe) files whereas CLASSPATH is used to specify the location of class files
- 2. Is Java a pure object oriented language? Discuss
Correct Answer: Java uses primitive data types and hence is not a pure object oriented language
- 3. How to define a constant variable in Java? Discuss
Correct Answer: The variable should be declared as static and final So only one copy of the variable exists for all instances of the class and the value can't be changed also static final int PI = 214; is an example for constant
- 4. What is the access scope of a protected method? Discuss
Correct Answer: A protected method can be accessed by the classes within the same package or by the subclasses of the class in any package
- 5. What is the impact of declaring a method as final? Discuss
Correct Answer: A method declared as final can't be overridden A sub-class can't have the same method signature with a different implementation
- 6. Which of the following is not used for commenting in java?
Options- A. //
- B. /* */
- C. /** */
- D. /** **/ Discuss
- // is a single line comment
- /* */ is commenting on one or more lines
- /** */ is documentation comment
Correct Answer: /** **/
Explanation:
- 7. Which is true?
Options- A. "X extends Y" is correct if and only if X is a class and Y is an interface
- B. "X extends Y" is correct if and only if X is a class and Y is an interface
- C. "X extends Y" is correct if X and Y are either both classes or both interfaces
- D. "X extends Y" is correct for all combinations of X and Y being classes and/or interfaces Discuss
Correct Answer: "X extends Y" is correct if X and Y are either both classes or both interfaces
Explanation:
A is incorrect because classes implement interfaces, they don't extend them. B is incorrect because interfaces only "inherit from" other interfaces. D is incorrect based on the preceding rules.
- 8. class Hell { public static void main(String[] args) { Integer i = 42; String s = (i<40)?"life":(i>50)?"base":"ball"; System.out.println(s); } }
Options- A. null
- B. ball
- C. base
- D. None Discuss
Correct Answer: ball
Explanation:
D is correct. This is a ternary nested in a ternary with a little unboxing thrown in.Both of the ternary expressions are false.
- 9. try { int x = Integer.parseInt("two"); } Which could be used to create an appropriate catch block?
Options- A. ClassCastException
- B. IllegalStateException
- C. NumberFormatException
- D. None Discuss
Correct Answer: NumberFormatException
Explanation:
C is correct. 'Integer.parseInt' can throw a NumberFormatException, and IllegalArgumentException is its superclass
- 10. Difference between Java Beans & Servlets? Discuss
Correct Answer: java bean is a reusable component, where as the servlet is the java program which extends the server capability
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Programming
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