Most useful software design patterns

Design patterns are the set of rules for solving problems in software development. In real-world software development, we face a lot of problems. When many of these problems have a common pattern then we can create a pattern out of it. We can use that solution pattern to solve similar problems.

A common tendency of a developer is to fit a problem into an established pattern. This approach is not wise. We should instead analyze the problem and if it matches an existing pattern just use it. Sometimes we may need multiple patterns to solve one problem. Sometimes the same problem can be solved with two different patterns.

The developer conversation can also be improved with the help of design patterns in our day-to-day coding. Let’s say that a senior developer knows that a particular problem can be solved with a particular design pattern. The senior member then can guide the other team members to use that design pattern instead of asking other developers to write 20 different classes.

The design patterns are for better software design. We can get the best use of it if we try to practice design patterns in our day-to-day coding properly. Following are some most used design patterns:


The singleton design pattern is the pattern when a single class is responsible for creating the only instance and making sure the availability of the instance. The class provides a way to access its only instance without needing to create a new instance.

Factory Method

In the factory method without specifying the exact class, the objects are created by calling a factory method instead of calling a constructor.


The strategy pattern allows grouping related algorithms under an abstraction, which lets you then switch out one algorithm or policy for another without modifying the client. Instead of directly implementing a single algorithm, the code receives runtime instructions specifying which of the group of algorithms to run. Yay!


This pattern is a one-to-many dependency between objects so that when one object changes state, all its dependents are notified. This is typically done by calling one of their methods.


A builder pattern is used to build objects. Crazy, right? Sometimes, the objects you need to create are complex, made up of several sub-objects, or require an elaborate construction process. The exercise of creating complex types can be simplified by using the builder pattern. A composite of an aggregate object is what a builder generally builds.

  • Builder pattern is more readable: It allows named parameters so that the call isn’t just a long list of unnamed arguments
  • Builder pattern is unordered: – It allows us to group arguments together into logical groups.


This allows incompatible classes to work together by converting the interface of one class into another. Think of it as a sort of translator: when two heads of state who don’t speak a common language meet, usually an interpreter sits between the two and translates the conversation, thus enabling communication.

We usually use it when we deal with different interfaces with similar behavior.


The state pattern is one of the behavioral design patterns. The class behavior is changed based on its state. The State design pattern is used when an object changes its behavior based on its internal state.