As you can see, a new array of characters is created with a size of the length of the existing value plus the size of value that is appended. Then, their value is copied to the new array instance. Finally, a new String object is created from the array and returned. To solve this problem, the StringBuilder class is used. It works like a mutable String object. The append method helps to avoid all the copying required in string concatenation.
However, Java does this string concatenation using StringBuilder by default for the simple cases.. From the Java specifications :. To increase the performance of repeated string concatenation, a Java compiler may use the StringBuffer class or a similar technique to reduce the number of intermediate String objects that are created by evaluation of an expression. The above code will produce the following bytecode:.
As you can see in the bytecode, StringBuilder is used. Thanks once again Joe. Great discussion Joe. Yes it has an issue in the table. Best performance from StringBuilder.
Is it? Since Kasuntha says:. Joe says:. A says:. Javapapers Facebook Page. Improve Article. Like Article. Next Reverse a string in Java. Recommended Articles. Article Contributed By :. Easy Normal Medium Hard Expert. Writing code in comment? Please use ide. Load Comments. What's New. Output: true false. Set ; import java.
Output: java. StringBuilder cannot be cast to java. We can create a String object without using a new operator, which is not possible with a StringBuilder. StringBuilder is speedy and consumes less memory than a string while performing concatenations. This is because string is immutable in Java, and concatenation of two string objects involves creating a new object.
To illustrate, consider the following code, which logs the time taken by both string and StringBuilder objects on multiple concatenations. Output will vary : The time taken by string concatenation: ns The time taken by StringBuilder concatenation: ns.
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