Assignment to 'catch' block parameter

Reports assignments to, catch block parameters.

Changing a catch block parameter is very confusing and should be discouraged.

The quick-fix adds a declaration of a new variable.

Example:

  void processFile(String fileName) throws Exception {
    try {
      doProcessFile(fileName);
    } catch(Exception ex) {
      if (ex instanceof UncheckedIOException) {
        // Warning: catch block parameter reassigned
        ex = ((UncheckedIOException) ex).getCause();
      }
      throw ex;
    }
  }

After the quick-fix is applied:

  void processFile(String fileName) throws Exception {
    try {
      doProcessFile(fileName);
    } catch(Exception ex) {
      Exception unwrapped = ex;
      if (unwrapped instanceof UncheckedIOException) {
        unwrapped = ((UncheckedIOException)
          unwrapped).getCause();
      }
      throw unwrapped;
    }
  }

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.

AssignmentToCatchBlockParameter

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 | Assignment issues

Inspection ID: AssignmentToCatchBlockParameter

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 AssignmentToCatchBlockParameter

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