A.data memory optimization

B.data hiding

C.data validation

D.data abstraction

E.compile time polymorphism

A.String main 1

B.String main 123

C.String main 1 2 3

D.An exception is thrown at runtime

A.No Match

B.Match 2

C.A NullPointerException is thrown at runtime.

D.Match 1

A.Replace line 5 With String opt= "true";Replace line 7 with case "true":

B.Remove the default section.

C.Replace line 5 with boolean opt = l;Replace line 7 with case 1

D.At line 9, remove the break statement.

A.String str2 = sb1. toString();

B.String str2 = str1;

C.String str2 = new String(str1);

D.String str2 = "Duke";