Non-constant string concatenation as argument to logging call

Reports non-constant string concatenations that are used as arguments to SLF4J and Log4j 2 logging methods. Non-constant concatenations are evaluated at runtime even when the logging message is not logged; this can negatively impact performance. It is recommended to use a parameterized log message instead, which will not be evaluated when logging is disabled.

Example:

  public class Vital {
    private static final Logger LOG = LoggerFactory.getLogger(Vital.class);

    public void saveTheWorld(int i, String s, boolean b) {
      LOG.info("saveTheWorld(" + i + ", " + s + ", "  + b + ")");
      // todo
    }
  }

After the quick-fix is applied:

  public class Vital {
    private static final Logger LOG = LoggerFactory.getLogger(Vital.class);

    public void saveTheWorld(int i, String s, boolean b) {
      LOG.info("saveTheWorld({}, {}, {})", i, s, b);
      // todo
    }
  }

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.

StringConcatenationArgumentToLogCall

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Java | Logging

Configure the inspection:

Use the Warn on list to ignore certain higher logging levels. Higher logging levels may be enabled even in production, and the arguments will always be evaluated.

Inspection ID: StringConcatenationArgumentToLogCall

Inspection options

Here you can find the description of settings available for the Non-constant string concatenation as argument to logging call inspection, and the reference of their default values.

Warn on

Option ID:

warnLevel

Default value:

all log levels

Other available settings:

warn level and lower
info level and lower
debug level and lower
trace level

For Log4j 2 use fixes as for parameterized logger

Option ID:

isLog4JParameterizedLogger

Default value:

Selected

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 StringConcatenationArgumentToLogCall

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

IntelliJ IDEA 2025.3

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.3, Qodana for JVM 2025.3,

Last modified: 03 December 2025