1. Discussion1 Quiz

2. Q1 Which of the following are invalid Java identifiers (variable names)? a) if b) n4m3 c) Java d) 12345 e) DEFAULT_VALUE f) bad-choice g) 1two3 h) first name i) last.name

3. A1 Which of the following are invalid Java identifiers (variable names)? a) if b) n4m3 c) Java d) 12345 e) DEFAULT_VALUE f) bad-choice g) 1two3 h) first name i) last.name

4. Q2 Which of these identifiers violate the naming convention for object names? a) R2D2 b) isthisokay? c) Java d) 3CPO e) ThisIsReallyOkay f) Java g) anotherbadone

5. A2 Which of these identifiers violate the naming convention for object names? a) R2D2 b) isthisokay? c) Java d) 3CPO e) ThisIsReallyOkay f) Java g) anotherbadone

6. Q3 What is the output of the following statements a) System.out.println( (a++)++ ); b) System.out.println( 2.5 == 5 / 2 ); c) System.out.println( 2.0 + 3/2 ); d) System.out.println( 5 % 3); e) System.out.println(5 + 4/2.0); f) float f = 1.1; System.out.println(f – 0.1); g) int a = 10; System.out.println(a = 11);

7. A3 What is the output of the following statements a) System.out.println( (a++)++ ); //error! b) System.out.println( 2.5 == 5 / 2 ); //false c) System.out.println( 2.0 + 3/2 ); //3.0 d) System.out.println( 5 % 3); //2 e) System.out.println(5 + 4/2.0); // 7.0 f) float f = 1.1; System.out.println(f – 0.1); //error! g) int a = 10; System.out.println(a = 11); //11

8. Q4 What is the result? boolean b1 = true; Boolean b2 = false; System.out.println(b1 || b2 = true); System.out.println(b1); System.out.println(b2);

9. A4 What is the result? boolean b1 = true; Boolean b2 = false; System.out.println(b1 || b2 = true); //b1 || b2 is evaluated first before = System.out.println(b1); System.out.println(b2);

10. Q5 What is the result? boolean b1 = true; Boolean b2 = false; System.out.println(b1 || (b2 = true)); System.out.println(b1); System.out.println(b2);

11. A5 What is the result? boolean b1 = true; Boolean b2 = false; System.out.println(b1 || (b2 = true)); //true System.out.println(b1); //true System.out.println(b2); //false

12. Q6 What is the result? boolean b1 = true; Boolean b2 = false; System.out.println(b1 && (b2 = true)); System.out.println(b1); System.out.println(b2);

13. A6 What is the result? boolean b1 = true; Boolean b2 = false; System.out.println(b1 && (b2 = true)); //true System.out.println(b1); //true System.out.println(b2); //true

14. Q7 What’s the output? String s1 = new String("John"); String s2 = new String("John"); if (s1 == s2) System.out.println("s1 == s2 is true"); else System.out.println("s1 == s2 is false");

15. A7 What’s the output? String s1 = new String("John"); String s2 = new String("John"); if (s1 == s2) System.out.println("s1 == s2 is true"); else System.out.println("s1 == s2 is false"); // s1 == s2 is false

16. Q8 Is there any problem with this? int a = 10; double b = 1.0; a = a + b; System.out.println(a);

17. A8 Is there any problem with this? int a = 10; double b = 1.0; a = a + b; //type error System.out.println(a);

18. Q8 Is there any problem with this? int a = 10; double b = 1.0; a += b; System.out.println(a);

19. A8 Is there any problem with this? int a = 10; double b = 1.0; a += b; System.out.println(a); //no problem! lhs op= rhs is actually lhs op= (type of lhs)rhs