Using 'instanceof' with patterns

Reports instanceof with patterns and suggests converting them to ordinary instanceof with casts.

This inspection makes it possible to move instanceof with patterns to a codebase using an earlier Java version by applying the quick-fix.

Note that the result can be not completely equivalent to the original instanceof with patterns when a complex expression before instanceof is used. In this case this expression will be reevaluated.

Example:

if (object instanceof String txt && txt.length() == 1) {
    System.out.println(txt);
} else {
    return;
}
System.out.println(txt);

After the quick-fix is applied:

if (object instanceof String && ((String) object).length() ==1) {
    String txt = (String) object;
    System.out.println(txt);
} else {
    return;
}
String txt = (String) object;
System.out.println(txt);

Inspection options

Option	Type	Default
Try to preserve unused variables from patterns during quickfix	Checkbox	true

Inspection Details
Available in:	IntelliJ IDEA 2023.3, Qodana for JVM 2023.3
Plugin:	Java, 233.SNAPSHOT

Last modified: 13 July 2023