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Optional

Theory

Check an Optional value

Report a typo

Method getValue of ValueProvider class returns Optional<String> result.

class ValueProvider {
    public Optional<String> getValue() {
        // hidden code
    }
}

Write a code in the Main class that prints the returning value of the provider.getValue if it is not null.

Write a program in Java 17
import java.util.Optional;

class Main {
public static void main(String[] args) {
ValueProvider provider = new ValueProvider();
// use provider.getValue() to get Optional<String>
}
}

class ValueProvider {
private Optional<String> inputOpt; // cache to provide reproducing method invocation

public Optional<String> getValue() {
if (inputOpt == null) {
java.util.Scanner scanner = new java.util.Scanner(System.in);
String input = scanner.next();
inputOpt = "null".equals(input) ? Optional.empty() : Optional.of(input);
}

return inputOpt;
}
}
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