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This module contains review questions and answers keyed to the module titled Jb0280: Java OOP: String and StringBuffer.

Revised: Tue Mar 29 11:29:05 CDT 2016

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This module contains review questions and answers keyed to the module titled Jb0280: Java OOP: String and StringBuffer .

The questions and the answers are connected by hyperlinks to make it easy for you to navigate from the question to the answer and back again.


Question 1 .

Java provides two different string classes from which string objects can be instantiated. What are they?

Answer 1

Question 2

True or false? The StringBuffer class is used for strings that are not allowed to change. The String class is used for strings that are modified by the program. If false, explain why.

Answer 2

Question 3

True or false? While the contents of a String object cannot be modified, a reference to a String object can be caused to point to a different String object. If false, explain why.

Answer 3

Question 4

True or false? The use of the new operator is required for instantiation of objects of type String . If false, explain your answer.

Answer 4

Question 5

True or false? The use of the new operator is required for instantiation of objects of type StringBuffer . If false, explain your answer

Answer 5

Question 6

Provide a code fragment that illustrates how to instantiate an empty StringBuffer object of a default length and then use a version of the append method to put some data into the object.

Answer 6

Question 7

Without specifying any explicit numeric values, provide a code fragment that will instantiate an empty StringBuffer object of the correct initial length to contain the string "StringBuffer named str6" and then store that string in the object.

Answer 7

Question 8

Provide a code fragment consisting of a single statement showing how to use the Integer wrapper class to convert a string containing digits to an integer and store it in a variable of type int .

Answer 8

Question 9

Explain the difference between the capacity method and the length method of the StringBuffer class.

Answer 9

Question 10

True or false? The following is a valid code fragment. If false, explain why.

StringBuffer str6 = new StringBuffer("StringBuffer named str6".length());

Answer 10

Question 11

Which of the following code fragments is the most efficient, first or second?

String str1 = "THIS STRING IS NAMED str1"; String str1 = new String("THIS STRING IS NAMED str1");

Answer 11

Question 12

Write a Java application that illustrates the fact that while a String object cannot be modified, the reference variable can bemodified to point to a new String object, which can have the appearance of modifying the original String object.

Answer 12

Question 13

Write a Java application that illustrates different ways to create String objects and StringBuffer objects.

Answer 13

Question 14

Write a Java application that illustrates conversion from string to numeric.

Questions & Answers

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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