Java string3/1/2023 ![]() ![]() We'd be greeted with an exception: incompatible types: int cannot be converted to String On the other hand, if we try to use the concat() method with a different data type: String str1 = "Hello" If we wanted the output to be "2 = 2" again, we'd need to add parentheses in the appropriate place. This is because of something called "operator precedence".Įssentially when two or more "+" operators are encountered (with no other operators present, nor parentheses) Java will start with the leftmost "+" operator and continue from there. However, this time, it won't - the output is "2 = 11". In regular circumstances, 1+1 would be evaluated first as Java deals with operations from right to left. Note: When using String concatenation with other data types, they implicitly get converted to their string representation: ( "2 = " + 2) We can also concatenate using the concat() method: String str1 = "Hello" StringBuilder sb = new StringBuilder( "") Not a good idea! Gives the right result, but performs poorly. It bypasses all the copying in string concatenation and gives us linear (O(n)) complexity. ![]() Usually, for something like that, we'd use the aforementioned StringBuilder class. Java automatically uses StringBuilder for concatenating several strings at once, so the source of the performance loss is concatenating in loops. This isn't a problem with small strings, or when we're concatenating just several strings at the same time ( String abcd = "a" + "b" + "c" + "d" ). ![]() This gives us quadratic (O(n^2)) complexity. String objects are immutable, so every time we wish to concatenate n strings Java has to copy the characters from all strings into a new String object. The operands can be String object reference variables as well The String class overloads that operator and it is used to concatenate two strings: String aplusb = "a" + "b" The String class comes with many helper methods that help us process our textual data:īefore we begin using any of these methods on strings, we should take a look at String concatenation as it's a fairly common thing to do. If not, refer to the previously linked article where it's explained in detail. Here, we're assuming that you're familiar with the fact that Strings are immutable, as it's a very important thing to know before handling them. There's a lot to say about Strings, from the ways you can initialize them to the String Literal Pool, however in this article we'll focus on common operations, rather than the class itself.Īlthough, if you'd like to read more about various ways of creating strings in Java you should check out String vs StringBuilder vs StringBuffer. Java's most used class is the String class, without a doubt, and with such high usage, it's mandatory for Java developers to be thoroughly acquainted with the class and its common operations. Simply put, a String is used to store text, i.e. ![]()
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