Conditional expression with negated condition

Reports conditional expressions whose conditions are negated.

Flipping the order of the conditional expression branches usually increases the clarity of such statements.

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.

NegatedConditional

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 | Control flow issues

Use the Ignore '!= null' comparisons and Ignore '!= 0' comparisons options to ignore comparisons of the form obj != null or num != 0. Since obj != null effectively means "obj exists", the meaning of the whole expression does not involve any negation and is therefore easy to understand.

The same reasoning applies to num != 0 expressions, especially when using bit masks.

These forms have the added benefit of mentioning the interesting case first. In most cases, the value for the == null branch is null itself, like in the following examples:

    static String getName(Person p) {
        return p != null ? p.getName() : null;
    }

    static String getExecutableString(int fileMode) {
        return (fileMode & 0b001001001) != 0 ? "executable" : "non-executable";
    }

Inspection options

Here you can find the description of settings available for the Conditional expression with negated condition inspection, and the reference of their default values.

Ignore '!= null' comparisons: Default: Selected
Ignore '!= 0' comparisons: Default: Selected

Availability

By default bundled with: IntelliJ IDEA 2024.1, Qodana for JVM 2024.1,
Can be installed with plugin: Java, 241.18072

Last modified: 18 June 2024