How do I concatenate two strings in Java?

You can concatenate Strings using the + operator:

System.out.println("Your number is " + theNumber + "!");

theNumber is implicitly converted to the String "42".

The concatenation operator in java is +, not .

Read this (including all subsections) before you start. Try to stop thinking the php way ;)

To broaden your view on using strings in Java - the + operator for strings is actually transformed (by the compiler) into something similar to:

new StringBuilder().append("firstString").append("secondString").toString()

There are two basic answers to this question:

1. [simple] Use the + operator (string concatenation). "your number is" + theNumber + "!" (as noted elsewhere)
2. [less simple]: Use StringBuilder (or StringBuffer).

StringBuilder value;value.append("your number is");value.append(theNumber);value.append("!");value.toString();

I recommend against stacking operations like this:

new StringBuilder().append("I").append("like to write").append("confusing code");

Edit: starting in java 5 the string concatenation operator is translated into StringBuilder calls by the compiler. Because of this, both methods above are equal.

Note: Spaceisavaluablecommodity,asthissentancedemonstrates.

Caveat: Example 1 below generates multiple StringBuilder instances and is less efficient than example 2 below

Example 1

String Blam = one + two;Blam += three + four;Blam += five + six;

Example 2

String Blam = one + two + three + four + five + six;