Click here to watch in Youtube :
https://www.youtube.com/watch?v=zqjl1ElyC2c&list=UUhwKlOVR041tngjerWxVccw

import java.util.ArrayList;
import java.util.List;

public class UnBoxingDemo
{

    public static void main(String[] args)
    {
        Integer integerObj = new Integer(-8);

        // 1. Unboxing through method invocation
        int absVal = absoluteValue(integerObj);
        System.out.println("absolute value of " + integerObj + " = " + absVal);

        List<Double> list = new ArrayList<>();
        list.add(new Double(12.3)); 

        // 2. Unboxing through assignment
        double doubleValue = list.get(0);
        System.out.println("doubleValue = " + doubleValue);

    }

    public static int absoluteValue(int i)
    {
        return (i < 0) ? -i : i;
    }

}