In Java, String concatenation is the operation of joining two or more Strings together. There are several ways to concatenate Strings in Java:
Using the + Operator: The + operator can be used to concatenate two Strings. This is the simplest and most commonly used method for String concatenation.
concatenate using + operator
String str1 = "Hello, ";
String str2 = "World!";
String str3 = str1 + str2; // "Hello, World!"
Using the concat() Method: The String class provides a method concat() to concatenate two strings.
Using concat() method
String str1 = "Hello, ";
String str2 = "World!";
String str3 = str1.concat(str2); // "Hello, World!"
Using StringBuilder or StringBuffer: For concatenating strings in a loop or in a scenario where a lot of modification is needed, it’s more efficient to use StringBuilder or StringBuffer.
Using StringBuilder
StringBuilder sb = new StringBuilder();
sb.append("Hello, ");
sb.append("World!");
String str = sb.toString(); // "Hello, World!"
Remember, while the + operator and concat() method are easy to use, they are not efficient for concatenating a large number of strings because String is immutable in Java, and each concatenation creates a new String object. In such cases, StringBuilder or StringBuffer should be used as they are mutable and don’t create a new object for each concatenation.
Understanding how to concatenate strings is a fundamental skill in Java, as it allows you to combine text data in a flexible and efficient manner. It’s especially important when dealing with user input or generating output, which often involve concatenating strings. By knowing how to concatenate strings, you can ensure that your programs are robust and efficient.
Tutorialsbox