Method Signatures and Return Types in AP CSA

Understanding how to read and write method signatures is fundamental to the entire AP exam. Every FRQ gives you a method header and expects you to implement it correctly.

Anatomy of a Method Signature

public    int    add    (int a, int b)
^          ^      ^       ^
access   return  name  parameters
modifier  type

Return Types

Common Return Mistakes

// ERROR: missing return in non-void method
public int getScore() {
    int score = 100;
    // forgot: return score;
}

// ERROR: returning wrong type
public int getScore() {
    return "100";  // can't return String from int method
}

// CORRECT
public int getScore() {
    return score;  // returns int, matches method signature
}

public static int mystery(int x) {
    if (x > 10) {
        return x * 2;
    }
    return x + 1;
}
System.out.println(mystery(10));
System.out.println(mystery(11));