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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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Table of contents

Preface

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.

Questions

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

Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
Kate Reply
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Kate Reply
what is the change in momentum of a body?
Eunice Reply
what is a capacitor?
Raymond Reply
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
Maria Reply
please solve
Sharon
8m/s²
Aishat
What is Thermodynamics
Muordit
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
Saheed Reply
50 m/s due south east
Someone
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
Ramon Reply
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
Someone
definitely of physics
Haryormhidey Reply
how many start and codon
Esrael Reply
what is field
Felix Reply
physics, biology and chemistry this is my Field
ALIYU
field is a region of space under the influence of some physical properties
Collete
what is ogarnic chemistry
WISDOM Reply
determine the slope giving that 3y+ 2x-14=0
WISDOM
Another formula for Acceleration
Belty Reply
a=v/t. a=f/m a
IHUMA
innocent
Adah
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
Nassze Reply
how do lnternal energy measures
Esrael
Two bodies attract each other electrically. Do they both have to be charged? Answer the same question if the bodies repel one another.
JALLAH Reply
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you. Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Robert
like charges repel while unlike charges atttact
Raymond
What is specific heat capacity
Destiny Reply
Specific heat capacity is a measure of the amount of energy required to raise the temperature of a substance by one degree Celsius (or Kelvin). It is measured in Joules per kilogram per degree Celsius (J/kg°C).
AI-Robot
specific heat capacity is the amount of energy needed to raise the temperature of a substance by one degree Celsius or kelvin
ROKEEB
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Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
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