OptionalInt orElseThrow(Supplier) method in Java with examples

Last Updated : 27 May, 2019
The orElseThrow(Supplier) method of OptionalInt class used to get the value contained by OptionalInt. If a value is present, this method returns the value, otherwise, this method throws an exception produced by the exception supplying function. The exception Supplier function is passed as a parameter. Syntax: 
public <X extends Throwable> int 
    orElseThrow(Supplier<?X> exceptionSupplier)
        throws X extends Throwable
Parameters: This method accepts one parameter exceptionSupplier which is the supplying function that produces an exception to be thrown. Return value: This method returns the value, if present. Exception: This method throw following Exceptions:
  • X - if no value is present.
  • NullPointerException - if no value is present and the exception supplying function is null
  • X extends Throwable
Below programs illustrate orElseThrow(Supplier) method: Program 1: Java 
// Java program to demonstrate
// OptionalInt.orElseThrow(Supplier) method
import java.util.OptionalInt;

public class GFG {

    public static void main(String[] args)
    {

        // create a OptionalInt
        OptionalInt opint
            = OptionalInt.of(24);

        // apply orElseThrow(Supplier)
        int value
            = opint.orElseThrow(ArithmeticException::new);

        System.out.println("value " + value);
    }
}
Output: Program 2: Java 
// Java program to demonstrate
// OptionalInt.orElseThrow(Supplier) method
import java.io.IOException;
import java.util.OptionalInt;

public class GFG {

    public static void main(String[] args)
    {

        // create a OptionalInt
        OptionalInt opint
            = OptionalInt.empty();

        // apply orElseThrow(Supplier)
        int value;

        try {

            value
                = opint.orElseThrow(IOException::new);
        }
        catch (IOException e) {

            System.out.println("Exception " + e);
        }
    }
}
Output: References: https://docs.oracle.com/javase/10/docs/api/java/util/OptionalInt.html#orElseThrow(java.util.function.Supplier)
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