Recursive Java methods and terminating arguments

≈ 45 min

Recursive Java methods and terminating arguments

Java recursion uses ordinary methods, but the runtime creates a new stack frame for every call. The method signature and parameter choice should make progress easy to see. An index can increase toward array.length, a number can decrease toward zero, or an interval can shrink until low exceeds high. Use a parameter that measures the remaining work rather than hiding progress in global state.

Each frame has its own local variables. If a recursive call changes the wrong variable or reuses the same argument, the base case may never be reached. A correct method also handles boundary inputs explicitly: an empty array, zero digits or an interval with no values. These cases are part of the contract, not exceptional afterthoughts.

Worked reasoning. A recursive contains method searches an array from index i. If i equals values.length, return false because no values remain. If values[i] matches target, return true. Otherwise call contains(values, target, i + 1). The index is the terminating argument because it advances across the finite array.

Exam lens. Read the base case before tracing the recursive case. Then state how the argument changes and why it cannot move forever.

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Which statement is the most defensible principle for Recursive Java methods and terminating arguments?

A recursive Java method must make a smaller call on an argument with a measurable path to the base case.

Treat an implementation detail as more important than the stated rule.

Assume one successful run proves the system is correct in every case.

Avoid recording assumptions, limits or failure conditions.

Enter the key term for Recursive Java methods and terminating arguments. What part of a recursive call must move toward the base case?

A recursive binary search changes low to mid + 1 or high to mid - 1. Why does this terminate on a finite sorted array?

Each call removes at least the midpoint from the remaining interval, so the interval eventually becomes empty or finds the target.

Use a larger class or broader permission without stating a rule.

Trust the first output and skip a boundary or failure check.

Hide the decision so affected people cannot inspect it.

Name the concise safeguard or principle that completes this lesson’s scenario: A recursive binary search changes low to mid + 1 or high to mid - 1. Why does this terminate on a finite sorted array?