Expression is compared to itself

Reports comparisons where left and right operand represent the identical expression. While sometimes comparison of an expression with itself could be intended, in most cases they are the result of an oversight.

Example:

  // Probably left.getLength() == right.getLength() was intended
  boolean result = left.getLength() == left.getLength();

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.

ExpressionComparedToItself

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 | Probable bugs

To ignore comparisons that may produce side effects, use the Ignore conditions with side effects option. Disabling this option may lead to false-positives, for example, when the same method returns different values on subsequent invocations.

Example:

  native int unknownMethod();
  
  ...
  
  if (unknownMethod() > unknownMethod()) {
    System.out.println("Got it");
  }

Due to possible side effects of unknownMethod() (on the example), the warning will only be triggered if the Ignore conditions with side effects option is disabled.

New in 2024.2

Inspection options

Here you can find the description of settings available for the Expression is compared to itself inspection, and the reference of their default values.

Ignore conditions with possible side effects: Not selected

Inspection Details
By default bundled with:	IntelliJ IDEA 2024.2, Qodana for JVM 2024.2,
Can be installed with plugin:	Java, 242.22892

Last modified: 11 September 2024