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It is important to note that the following statement does not modify the original object pointed to by the reference variable named str1 .

thisObj.str1 = thisObj.str1 + " " + thisObj.str2;

Rather, this statement creates a new object, which is concatenation of two existing objects and causes the reference variable named str1 to point to the new object instead of the original object.

The original object then becomes eligible for garbage collection (unless there is another reference to the object hanging around somewhere) .

Many aspects of string manipulation can be accomplished in this manner, particularly when the methods of the String class are brought into play.

Why are there two string classes?

According to The Java Tutorial by Campione and Walrath:

"Because they are constants, Strings are typically cheaper than StringBuffers and they can be shared. So it's important to use Stringswhen they're appropriate."

Creating string and stringbuffer objects

The String and StringBuffer classes have numerous overloaded constructors and many different methods. I will attempt to provide asampling of constructors and methods that will prepare you to explore other constructors and methods on your own.

The next sample program touches on some of the possibilities provided by the wealth of constructors and methods in the String and StringBuffer classes.

At this point, I will refer you to Java OOP: Java Documentation where you will find a link to online Java documentation. Among other things, the online documentation provides a list of theoverloaded constructors and methods for the String and StringBuffer classes.

As of Java version 7, there are four overloaded constructors in the StringBuffer class and about thirteen different overloaded versions of the append method. There are many additional methods in the StringBuffer class including about twelve overloaded versions of the insert method.

As you can see, there are lots of constructors and lots of methods from which to choose. One of your challenges as a Java programmer will be to find the rightmethods of the right classes to accomplish what you want your program to accomplish.

The sample program named string02

The sample program shown in Listing 2 illustrates a variety of ways to create and initialize String and StringBuffer objects.

Listing 2 . File String02.java.
/*File String02.java Copyright 1997, R.G.Baldwin Illustrates different ways to create String objects andStringBuffer objects. The program was tested using JDK 1.1.3 under Win95.The output from this program is as follows. In some cases, manual line breaks were inserted to make the material finthis presentation format. Create a String the long way and display itString named str2 Create a String the short way and display itString named str1 Create, initialize, and display a StringBuffer using newStringBuffer named str3 Try to create/initialize StringBuffer withoutusing new - not allowedCreate an empty StringBuffer of default length Now put some data in it and display itStringBuffer named str5 Create an empty StringBuffer and specify lengthwhen it is created Now put some data in it and display itStringBuffer named str6 Try to create and append to StringBuffer withoutusing new -- not allowed **********************************************************/class String02{ void d(String displayString){//method to display stringsSystem.out.println(displayString); }//end method d()public static void main(String[] args){String02 o = new String02();//obj of controlling classo.d("Create a String the long way and display it"); String str1 = new String("String named str2");o.d(str1 + "\n");o.d("Create a String the short way and display it"); String str2 = "String named str1";o.d(str2 + "\n");o.d("Create, initialize, and display a StringBuffer " + "using new");StringBuffer str3 = new StringBuffer( "StringBuffer named str3");o.d(str3.toString()+"\n"); o.d("Try to create/initialize StringBuffer without " +"using new - not allowed\n"); //StringBuffer str4 = "StringBuffer named str4";xo.d("Create an empty StringBuffer of default length");StringBuffer str5 = new StringBuffer();o.d("Now put some data in it and display it"); //modify length as neededstr5.append("StringBuffer named str5"); o.d(str5.toString() + "\n");o.d("Create an empty StringBuffer and specify " +"length when it is created"); StringBuffer str6 = new StringBuffer("StringBuffer named str6".length()); o.d("Now put some data in it and display it");str6.append("StringBuffer named str6"); o.d(str6.toString() + "\n");o.d("Try to create and append to StringBuffer " +"without using new -- not allowed"); //StringBuffer str7;//str7.append("StringBuffer named str7"); }//end main()}//end class String02

Questions & Answers

how did you get 1640
Noor Reply
If auger is pair are the roots of equation x2+5x-3=0
Peter Reply
Wayne and Dennis like to ride the bike path from Riverside Park to the beach. Dennis’s speed is seven miles per hour faster than Wayne’s speed, so it takes Wayne 2 hours to ride to the beach while it takes Dennis 1.5 hours for the ride. Find the speed of both bikers.
MATTHEW Reply
420
Sharon
from theory: distance [miles] = speed [mph] × time [hours] info #1 speed_Dennis × 1.5 = speed_Wayne × 2 => speed_Wayne = 0.75 × speed_Dennis (i) info #2 speed_Dennis = speed_Wayne + 7 [mph] (ii) use (i) in (ii) => [...] speed_Dennis = 28 mph speed_Wayne = 21 mph
George
Let W be Wayne's speed in miles per hour and D be Dennis's speed in miles per hour. We know that W + 7 = D and W * 2 = D * 1.5. Substituting the first equation into the second: W * 2 = (W + 7) * 1.5 W * 2 = W * 1.5 + 7 * 1.5 0.5 * W = 7 * 1.5 W = 7 * 3 or 21 W is 21 D = W + 7 D = 21 + 7 D = 28
Salma
Devon is 32 32​​ years older than his son, Milan. The sum of both their ages is 54 54​. Using the variables d d​ and m m​ to represent the ages of Devon and Milan, respectively, write a system of equations to describe this situation. Enter the equations below, separated by a comma.
Aaron Reply
find product (-6m+6) ( 3m²+4m-3)
SIMRAN Reply
-42m²+60m-18
Salma
what is the solution
bill
how did you arrive at this answer?
bill
-24m+3+3mÁ^2
Susan
i really want to learn
Amira
I only got 42 the rest i don't know how to solve it. Please i need help from anyone to help me improve my solving mathematics please
Amira
Hw did u arrive to this answer.
Aphelele
hi
Bajemah
-6m(3mA²+4m-3)+6(3mA²+4m-3) =-18m²A²-24m²+18m+18mA²+24m-18 Rearrange like items -18m²A²-24m²+42m+18A²-18
Salma
complete the table of valuesfor each given equatio then graph. 1.x+2y=3
Jovelyn Reply
x=3-2y
Salma
y=x+3/2
Salma
Hi
Enock
given that (7x-5):(2+4x)=8:7find the value of x
Nandala
3x-12y=18
Kelvin
please why isn't that the 0is in ten thousand place
Grace Reply
please why is it that the 0is in the place of ten thousand
Grace
Send the example to me here and let me see
Stephen
A meditation garden is in the shape of a right triangle, with one leg 7 feet. The length of the hypotenuse is one more than the length of one of the other legs. Find the lengths of the hypotenuse and the other leg
Marry Reply
how far
Abubakar
cool u
Enock
state in which quadrant or on which axis each of the following angles given measure. in standard position would lie 89°
Abegail Reply
hello
BenJay
hi
Method
I am eliacin, I need your help in maths
Rood
how can I help
Sir
hmm can we speak here?
Amoon
however, may I ask you some questions about Algarba?
Amoon
hi
Enock
what the last part of the problem mean?
Roger
The Jones family took a 15 mile canoe ride down the Indian River in three hours. After lunch, the return trip back up the river took five hours. Find the rate, in mph, of the canoe in still water and the rate of the current.
cameron Reply
Shakir works at a computer store. His weekly pay will be either a fixed amount, $925, or $500 plus 12% of his total sales. How much should his total sales be for his variable pay option to exceed the fixed amount of $925.
mahnoor Reply
I'm guessing, but it's somewhere around $4335.00 I think
Lewis
12% of sales will need to exceed 925 - 500, or 425 to exceed fixed amount option. What amount of sales does that equal? 425 ÷ (12÷100) = 3541.67. So the answer is sales greater than 3541.67. Check: Sales = 3542 Commission 12%=425.04 Pay = 500 + 425.04 = 925.04. 925.04 > 925.00
Munster
difference between rational and irrational numbers
Arundhati Reply
When traveling to Great Britain, Bethany exchanged $602 US dollars into £515 British pounds. How many pounds did she receive for each US dollar?
Jakoiya Reply
how to reduced echelon form
Solomon Reply
Jazmine trained for 3 hours on Saturday. She ran 8 miles and then biked 24 miles. Her biking speed is 4 mph faster than her running speed. What is her running speed?
Zack Reply
d=r×t the equation would be 8/r+24/r+4=3 worked out
Sheirtina
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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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