String concatenation as argument to 'MessageFormat.format()' call

Reports non-constant string concatenations used as an argument to a call to MessageFormat.format().

While occasionally intended, this is usually a misuse of the formatting method and may even cause unexpected exceptions if the variables used in the concatenated string contain special characters like {.

Also, sometimes this could be the result of mistakenly concatenating a string format argument by typing a + when a , was meant.

Example:

  String formatGreeting(String userName, int balance) {
    return MessageFormat.format("Hello, " + userName + "! Your balance is {0}.", balance);
  }

Here, the userName will be interpreted as a part of the format string, which may result in IllegalArgumentException (for example, if userName is "{"). This call should be probably replaced with MessageFormat.format("Hello, {0}! Your balance is {1}.", userName, balance).

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

StringConcatenationInMessageFormatCall

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Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection StringConcatenationInMessageFormatCall

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

IntelliJ IDEA 2025.2

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.2, Qodana for JVM 2025.2,

Last modified: 18 September 2025