Correct Answer: JAR files are java's version of ZIP files In fact, JAR uses the ZIP file format uses: - to compress a number of class files into one file - to make a java executable JAR file
Correct Answer: Unwrapping is also called as unpacking or unboxing Getting the private data stored in the object by using methods is called unpacking or unwrapping
Correct Answer: Wrapping is also called as packing or boxing Storing the data inside the object as private data which can accessed outside the class only by using methods
5. What is different among String, StringBuffer, StringBuilder?
Correct Answer: String class objects are immutable objects and they represents strings( sequence of characters) StringBuffer class objects are mutable objects representing strings and they are Thread safe StringBuild class objects are also mutable objects representing strings and they are not Thread safe
6. If super class ref is pointing sub class object then by using super class ref is it possible to call sub class newly defined method?
Correct Answer: - By using method overriding a sub class can change the definition of super class method - By using overriding a sub class can modify the functionality of the super class
8. What is the use of overloading ? or why overloading?
Correct Answer: Final method is a method defined in the super class with final modifier We cannot overriding final method of super class in the sub class EX: Class Sample { final void funOne() { } void funTwo() { } } Class Sub extends Sample { void funOne() { // overriding is not allowed } viod funTwo() { //overriding is allowed } }
10. What is the purpose of overriding toString() method?