AP CSA — Hard Java Logic & Edge Cases

Front

Integer Overflow & Wrapping

Back

Integer types (int) wrap around if they exceed their maximum value. Adding 1 to Integer.MAX_VALUE results in Integer.MIN_VALUE. Always check for bounds before arithmetic operations to prevent logical errors in counting loops.

Front

Integer Division vs. Double Division

Back

In Java, division between two integers results in an integer (truncating the decimal). To retain decimal precision, at least one operand must be a double. Example: 5 / 2 evaluates to 2, while 5.0 / 2 evaluates to 2.5.

Front

Postfix vs. Prefix Increment in Expressions

Back

Prefix (++x) increments the value before the expression is evaluated; Postfix (x++) uses the original value in the expression and increments afterward. Example: int x = 5; int y = x++; results in y being 5 and x becoming 6.

Front

Short-Circuit Evaluation with && and ||

Back

Java evaluates logical operators from left to right and stops as soon as the result is determined. In (cond1 || cond2), if cond1 is true, cond2 is never evaluated. This prevents NullPointerExceptions if the second check depends on the first being true.

Front

String Object Equality (== vs. .equals)

Back

The == operator compares references (memory addresses), while .equals() compares the actual content of the strings. Two String objects with the same characters will return false with == but true with .equals().