codeql/java/ql/src/Language Abuse/LabelInSwitch.md

Overview

Java allows to freely mix case labels and ordinary statement labels in the body of a switch statement. However, this is confusing to read and may be the result of a typo.

Recommendation

Examine the non-case labels to see whether they were meant to be case labels. If not, consider placing the non-case label headed code into a function, and use a function call inline in the switch body instead.

Example

public class Test {
    void test_noncase_label_in_switch(int p) {
        switch (p) {
            case 1: // Compliant
            case2:  // Non-compliant, likely a typo
            break;
            case 3:
                notcaselabel: // Non-compliant, confusing to read
                for (;;) {
                    break notcaselabel;
                }
        }
    }
}

In the example, case2 is most likely a typo and should be fixed. For the intentional notcaselabel, placing the labelled code into a function and then calling that function is more readable.

References

CodeQL query help for JavaScript and TypeScript - Non-case label in switch statement.