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An argument is a value or expression passed as input to a method, and a parameter is a variable defined within the method to hold this input. In Java, a null value represents the absence of a value, and attempting to perform operations on a null value parameter will result in a Null Pointer Exception. Similarly, if a method returns a null value, the caller should handle it appropriately to avoid a NullPointerException. However, it is generally recommended to avoid returning null values whenever possible. Let’s take a look at the example method… public static Double average(final Double... values) {   if (values == null) {     return null;   }   if (values.length == 0) {     return null;   }   double total = 0.0;   for (double value : values) {     total += value;   }   return total / values.length; } Will this fail at compile time? No Will it fail at runtime? Yes An array can be null or empty. In this case, if the arr...

 PATTERN PROBLEM In a previous post, I showed you how the OOP world looks like.  OOP is a pretty convenient paradigm for identifying requirements while also making them easier to understand. Different OOP concepts like inheritance and polymorphism have a number of use cases in popular applications. However, in some situations, OOP on its own is not enough. To implement a particular feature, you may need to use OOP concepts in a way that makes your code better and more understandable. In this post, you’ll learn 5 design patterns that can make your life better as a Java programmer. Before that, let’s get two things out of the way. Why Design Patterns? Let’s take a class  Boat  that has different sub classes representing the types of boats. A  Boat  object performs two actions, sway and roll. abstract class Boat { void sway () { ... } void roll () { ... } abstract void present () ; } The  sway()  and  roll()  methods ar...