What is the output of this program? (or, can it be compiled)?

Basic Java Task 5

1. 
   What is the output of this program? (or, can it be compiled)?
   

class Test { public static void main(String[] args) { System.out.println(f((int)5)); } public static String f(String n) { System.out.print("string "); return n; } public static long f(long n) { System.out.print("long "); return n; } }

Ans: The output of this program is: long 5.

2. 
   The following JavaFX layout is best implemented using?
   
   

3. 
   What exception will arise from this following code, explain it!
   

System.out.println(Byte.parseByte("123456789")); Ans: There is a number format Exception and also the value is out of range.

4. 
   What does the following code print? Explain it!
   

int x = 5; for(int i = 0; i < 10; i++) { switch(i%3) { case 0: x += 2; default: x += 1; } } System.out.println(x); Ans: The output of above code is given below:

5. 
   What does the following code print? Explain it!
   

int i = 0; int j = 20; try { j = i/2; i = (j+1)/j+1; } catch(ArithmeticException e) { i = 30; j = 50; } catch(Exception e) { i = 8; j = 9; } finally { i -= 10; j += 10; } System.out.println(i + j); Ans: The output of the above program is given below:

6. 
   Given the definitions of class A, class B, and interface C as follows. Will everything be compiled successfully? Choose your answer.
   

a. C c = new C(); // yes /no [Ans: yes]

b. C c = new A(); // yes /no [ Ans: yes]

c. C c = new B(); // yes /no [Ans: no]

interface C { } class A implements C { } class B { }

7. 
   Given this code, what will be return value of h (41)? Explain it.
   

public static int h(int i) { return i<=1?1:i-h(i/2); } Ans: The return value of h (41) is: 27.

8. 
   What is information hiding in Java? Give an example!
   

Ans:

• 
  In programming, the process of hiding details of an object or function. Information hiding is a powerful programming technique because it reduces complexity. One of the chief mechanisms for hiding information is encapsulation -- combining elements to create a larger entity. The programmer can then focus on the new object without worrying about the hidden details. In a sense, the entire hierarchy of programming languages, from machine languages to high-level languages, can be seen as a form of information hiding.
  
• 
  Information hiding is also used to prevent programmers from intentionally or unintentionally changing parts of a program.
  
• 
  Encapsulation in Java is a mechanism of wrapping the data (variables) and code acting on the data (methods) together as a single unit. In encapsulation, the variables of a class will be hidden from other classes, and can be accessed only through the methods of their current class. Therefore, it is also known as data hiding.
  
• 
  To achieve encapsulation in Java :
  

-Declare the variables of a class as private.

-Provide public setter and getter methods to modify and view the variables values.

9. 
   What does the following code print? Assume the “File.txt” is not available. Explain it.
   

try { try (BufferedReader br = new BufferedReader(new FileReader("File.txt"))) { System.out.print("1"); } } catch(ArithmeticException e) { System.out.print("2"); } catch(IOException e) { System.out.print("3"); } finally { System.out.print("4"); }