Explain: IllegalStateException, stream has already been operated upon or closed.

A Stream should be operated o only once. A Stream implementation may throw IllegalStateException if it detects that the Stream is being reused.

Whenever a terminal operation is called on a Stream object, the instance gets consumed and closed. Therefore, it is allowed to perform a single operation that consumes a Stream, otherwise, an exception is encountered that states that the Stream has already been operated upon or closed.

public class LargestAndSmallest {

	public static void main(String[] args) {
		Stream<Integer> myIntStream = Stream.of(1, 2, 3, 44, 556, -1, 0, 2234);
		System.out.println("Largest = " + myIntStream.reduce(Integer::max));
		// The below line will throw java.lang.IllegalStateException

		System.out.println("Smallest = " + myIntStream.reduce(Integer::min));
	}

}

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