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Next is a recommendation from Effective Java I am 51.

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It says beware the performance of string concatenation.

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Let's see what exactly it has to say.

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It says a bless operator is a convenient way to combine few strings and it shouldn't be used to combine

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more than few strengths unless performance is irrelevant.

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This is because with each concatenation these steps are being performed condense of both strings are

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first copied then a new String object is created and is appended with both the strings.

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Finally a new string is generated by invoking the string method on the string builder object.

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So these steps are being performed with each concatenation.

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Let's look at an example.

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Let's assume there is an array with three strings A B and C that are to be concatenated in a for loop

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.

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That is each iteration appends a string from the RV to understand the performance implication of using

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Pless operator.

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Let's consider the following statements which correspond to each iteration and the follow up.

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Let's assume s to be a string variable declared outskirt a for loop and is initialized with an empty

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string.

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The first statement corresponds to a statement execution during the first iteration and it is a concatenation

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between an empty string and a string.

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What does a copy of the string under string ARMH first and then they are concatenated in the second

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statement string as is up and there will be a copy of the current value of s.

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Registering a is made along with a copy of B and then the concatenation is performed similarly in the

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final statement.

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A copy of the current value of S is made with a string AB along with the copy of C and then the concatenation

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is performed.

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Also note that a string builder object is constructed for each of these concatenations.

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So as you can see it is quite expensive to use plus operator time complexity is quadratic as we have

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to create a copy of previously created string in each iteration that is and iteration requires a copy

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or string.

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Million and minus Vonte iteration.

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Similarly it is best consuming to add several strings that are getting created along with dust string

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builder objects.

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So item 51 recommends to use trng builder as it has a linear complexity.

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There is only one string builder object can be created out of the follow on in each iteration.

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A string can be appended to this object according to one benchmark string builder was found to be 300

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times faster than using plus operator.

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Similarly string builder was also found to be twice as fast as a string buffer.

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In this particular benchmark a string is constructed by looping for Iran sixteen thousand five hundred

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times.

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If you're interested in this benchmark just look at the link provided in the resource section.

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And that's about it.

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So you string builder.

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If performance is important.

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Use Pless operator only to combine fuse strings.

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Thank you