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Streamlining Java Code: Real-World Use Cases for Replacing Explicit Declarations with Var

As Java developers, we are always looking for ways to write more concise and readable code without sacrificing type safety. One powerful tool for achieving this goal is the var keyword, introduced in Java 10.

In this article, we’ll explore several real-world use cases where using var can simplify our code and improve readability.

Introduction

Java Local Variable Type Inference is a feature that was introduced in Java 10 to simplify the declaration of local variables. Instead of explicitly declaring the data type of a variable, developers can now use the var keyword to let the Java compiler infer the data type based on the context in which the variable is used.

For example, instead of declaring a variable with its data type like this:

PersonClass

Developers can use the var keyword like this:

PersonClass

Real-world use cases

  • Enhanced for-loop indexes:

The following code removes at most max matching entries from a Map. Wildcarded type bounds are used for improving the flexibility of the method, resulting in considerable verbosity. Unfortunately, this requires the type of the Iterator to be a nested wildcard, making its declaration more verbose.

PersonClass

  • Index variables declared in traditional for loops:

PersonClass

  • try-with-resources variable

Instead of the exact type, it’s sometimes better for a variable’s name to express the role or the nature of the variable, such as “customers”:

PersonClass

Overall, this article will provide a comprehensive overview of the useful use cases for var in Java, and help you write cleaner, more readable code.