Nested if Statements (EK 2.4.A.1 & 2.4.A.2)

A nested if is any selection statement that appears inside the body of another selection statement. Nesting lets you express conditions that only make sense to check after a prerequisite condition has passed. The critical rule from the CED: the boolean expression of the inner nested if is evaluated only if the boolean expression of the outer if evaluates to true.

This has a practical consequence: if the outer condition is false, the inner if is never reached at all, and any side effects inside the inner block do not occur. AP exam trace questions often exploit this by giving you an input where the outer condition is false and asking what happens — the answer is the inner block is completely skipped.

if (outerCondition) {
    // outer body: runs when outerCondition is true
    if (innerCondition) {
        // inner body: runs when BOTH conditions true
    } else {
        // inner else: runs when outer true, inner false
    }
} else {
    // outer else: runs when outerCondition is false
    // innerCondition is NEVER evaluated here
}

int score = 85;
if (score >= 60) {               // outer: 85 >= 60 = true
    if (score >= 90) {           // inner: 85 >= 90 = false
        System.out.println("A"); // SKIPPED
    } else {
        System.out.println("B"); // runs: outer true, inner false
    }
} else {
    System.out.println("F");     // SKIPPED: outer was true
}

Nested vs. separate if statements

A nested if inside an outer if body is fundamentally different from two separate if statements. With separate statements both conditions are always evaluated. With nesting, the inner condition is skipped when the outer is false. Use nesting when the inner question only makes logical sense after the outer condition passes.

// Nested: inner only runs when outer is true
if (isLoggedIn) {
    if (isAdmin) {
        System.out.println("Admin panel");
    }
}

// Separate: BOTH always checked, even when not logged in
if (isLoggedIn) { /* ... */ }
if (isAdmin) {                  // checked even when not logged in
    System.out.println("Admin panel");  // security flaw!
}

Multiway Selection: if-else-if (EK 2.4.A.3)

An if-else-if chain is a multiway selection that evaluates conditions in order from top to bottom. The moment a condition evaluates to true, its body executes and the rest of the chain is skipped entirely. At most one branch executes, regardless of how many conditions are true. If a trailing else is present, it executes only when all preceding conditions were false.

if (conditionA) {
    // executes when A is true (stops here)
} else if (conditionB) {
    // executes when A is false AND B is true (stops here)
} else if (conditionC) {
    // executes when A and B are false AND C is true
} else {
    // executes when ALL preceding conditions are false
    // (trailing else — optional but common)
}

int score = 85;
String grade;
if (score >= 90) {
    grade = "A";                 // 85 >= 90 = false, skip
} else if (score >= 80) {
    grade = "B";                 // 85 >= 80 = true → runs, DONE
} else if (score >= 70) {
    grade = "C";                 // never reached
} else {
    grade = "D or F";            // never reached
}
System.out.println(grade);       // B

if-else-if vs. separate if statements

Real-World Connection

Nested selection is everywhere. A bank ATM first checks if your card is valid (outer), then checks if your PIN is correct (inner) — the PIN check only happens if the card check passes. A streaming service first checks if you have an active subscription (outer), then checks if the content is in your region (inner). Tax bracket calculations use multiway if-else-if chains to assign exactly one rate based on income range. Every tiered system — shipping rates, hotel pricing, game difficulty levels — is a multiway selection in code.

Summary

• Nested if: a selection statement inside another selection statement. (EK 2.4.A.1)
• Inner condition is only evaluated when the outer condition is true. (EK 2.4.A.2)
• Multiway selection (if-else-if): evaluates conditions in order; at most one branch executes. (EK 2.4.A.3)
• Trailing else: catches the case when no condition in the chain is true.
• Order matters: most specific condition first in an if-else-if chain.
• Dangling else: always use braces in nested structures to make pairing explicit.
• Nested vs. separate: use nesting when the inner question only makes sense after the outer passes; use separate ifs when both are independent.

Nested if Statements

A nested if is a selection statement placed inside the body of another selection statement. The inner condition is only evaluated when the outer condition is true.

if (outerCondition) {
    if (innerCondition) {
        // both conditions true
    } else {
        // outer true, inner false
    }
}

int score = 85;
if (score >= 60) {
    if (score >= 90) {
        System.out.println("Excellent pass");
    } else {
        System.out.println("Standard pass");
    }
} else {
    System.out.println("Fail");
}

Multiway Selection: if-else-if

An if-else-if chain evaluates conditions in order. Only the first true branch executes. A trailing else runs when no condition is true.

if (conditionA) {
    // A true
} else if (conditionB) {
    // A false, B true
} else if (conditionC) {
    // A and B false, C true
} else {
    // none true
}

if (x > 0) {
    if (x > 5) {
        System.out.println("High");
    } else {
        System.out.println("Low");
    }
}

if (x > 0) {
    if (x > 5) {
        System.out.println("High");
    } else {
        System.out.println("Low");
    }
}

if (score >= 90) {
    System.out.println("A");
} else if (score >= 80) {
    System.out.println("B");
} else if (score >= 70) {
    System.out.println("C");
} else {
    System.out.println("F");
}

if (score >= 60) {
    System.out.println("Pass");
} else if (score >= 90) {
    System.out.println("Excellent");
} else {
    System.out.println("Fail");
}

if (temp >= 90) {
    System.out.println("Hot");
} else if (temp >= 70) {
    System.out.println("Warm");
} else if (temp >= 50) {
    System.out.println("Cool");
} else {
    System.out.println("Cold");
}

if (x > 5)
    if (x > 8)
        System.out.println("Very high");
else
    System.out.println("Low");

if (x > 2) {
    if (y > 5) {
        System.out.println("Both");
    } else {
        System.out.println("X only");
    }
} else {
    System.out.println("Neither");
}

if (age < 13) {
    System.out.println("Child");
} else if (age < 18) {
    System.out.println("Teen");
} else {
    System.out.println("Adult");
}

if (age >= 18) {
    System.out.println("Adult");
} if (age >= 13) {
    System.out.println("Teen");
} if (age < 13) {
    System.out.println("Child");
}

if (age < 18) {
    System.out.println("Teen");
} else if (age < 13) {
    System.out.println("Child");
} else {
    System.out.println("Adult");
}

if (age < 13) {
    System.out.println("Child");
} if (age < 18) {
    System.out.println("Teen");
} else {
    System.out.println("Adult");
}

if (n % 3 == 0) {
    if (n % 5 == 0) {
        System.out.println("FizzBuzz");
    } else {
        System.out.println("Fizz");
    }
} else if (n % 5 == 0) {
    System.out.println("Buzz");
} else {
    System.out.println("" + n);
}