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"if ... else if" Constructs Should End with "else" Clauses

High
reliabilitydefensive programming

What is it?​

This practice is triggered when an if statement is followed by one or more else if statements without concluding with an else statement.

Why apply it?​

Having a final else clause ensures logical completeness and provides a fallback path for unhandled conditions, which is a sign of robust and defensive programming.

How to fix it?​

End the if ... else if constructs with a final else statement, either handling the fallback case or providing a clear explanation of why no action is needed.

Examples​

Example 1:​

Negative​

The negative example lacks a concluding else clause, potentially leaving some unexpected conditions unhandled.

if (status.equals("active")) {
    processActiveStatus();
} else if (status.equals("inactive")) {
    processInactiveStatus();
}  /* Noncompliant */

Example 2:​

Positive​

The positive example includes a final else clause that throws an exception in case an unexpected condition arises, ensuring logical completeness.

if (status.equals("active")) {
    processActiveStatus();
} else if (status.equals("inactive")) {
    processInactiveStatus();
} else {
    throw new IllegalStateException("Unexpected status: " + status);  /* Compliant */
}

Negative​

The negative example does not provide an else clause, which could result in the method finishing without returning a value if the provided customerType is unhandled.

int getDiscountRate(String customerType) {
    if (customerType.equals("regular")) {
        return 5;
    } else if (customerType.equals("vip")) {
        return 10;
    }  /* Noncompliant */
}

Example 3:​

Positive​

The positive example completes the if ... else if construct with an else that returns a default value, demonstrating a complete decision path.

int getDiscountRate(String customerType) {
    if (customerType.equals("regular")) {
        return 5;
    } else if (customerType.equals("vip")) {
        return 10;
    } else {
        return 0;  /* Compliant */
    }
}