Boolean Expressions, Selection, and Control Flow
This topic tests relational operators, logical operators, if statements, if-else chains, short-circuit evaluation, De Morgan's laws, and path tracing.
How to study for AP Computer Science A
Build every answer by tracing Java state carefully: identify variables, objects, method calls, loops, collection indices, class responsibilities, and the exact output or return value.
Core concepts
Concept 1
Selection questions require tracing which branch executes and which branches are skipped.
Exam cue: Evaluate boolean expressions before deciding the branch.
Concept 2
Short-circuit evaluation can prevent errors and skipped side effects.
Exam cue: Check whether later else-if conditions can execute.
Concept 3
Compound conditions often need truth tables or careful substitution.
Exam cue: Use short-circuit rules with && and ||.
Risk pitfalls and guardrails
Treating independent if statements as an else-if chain.
Guardrail: Avoid answers that rely only on habit, ignore the stated source, skip safety or compliance steps, or choose convenience over the professional standard.
Forgetting that == compares primitive values but references for objects.
Guardrail: Avoid answers that rely only on habit, ignore the stated source, skip safety or compliance steps, or choose convenience over the professional standard.
Negating compound conditions incorrectly.
Guardrail: Avoid answers that rely only on habit, ignore the stated source, skip safety or compliance steps, or choose convenience over the professional standard.
Memory anchors
Boolean Expression
A boolean expression evaluates to true or false.
Relational Operator
A relational operator compares values and returns a boolean result.
Logical AND
Logical AND is true only when both operands are true.
Logical OR
Logical OR is true when at least one operand is true.
Short-Circuit Evaluation
Short-circuit evaluation skips the right operand when the result is already known.
If Statement
An if statement executes a block only when its condition is true.
Else If Chain
An else-if chain selects the first true branch.
De Morgan's Laws
De Morgan's laws transform negated compound boolean expressions.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What does this code print? int x = 5; if (x > 3) { System.out.println("big"); } else { System.out.println("small"); }
What does this print? int x = 2; if (x > 5) System.out.println("A"); else if (x > 1) System.out.println("B"); else System.out.println("C");
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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