Why the Diamond Operator was not Missed from Right Hand Side in Java 7
The Diamond Operator in Java 7 is a feature that allows you to omit the type argument on the right-hand side of a generic class instantiation. This feature was introduced to reduce the verbosity of code when working with generics. However, there are several reasons why this feature was not missed from the right-hand side in Java 7.
1. Type Inference
One of the main reasons why the Diamond Operator was not missed from the right-hand side in Java 7 is because of type inference. Type inference allows the compiler to infer the type arguments based on the context in which they are used. This means that you do not need to explicitly specify the type arguments when instantiating a generic class, as the compiler can automatically determine them based on the context.
For example, consider the following code snippet:
List<String> list = new ArrayList<>();
In this example, we have instantiated an ArrayList without specifying its type argument. The compiler can infer that we want an ArrayList of Strings based on the variable declaration (List<String> list). This reduces code verbosity and makes it easier to work with generics.
2. Improved Readability
Another reason why the Diamond Operator was not missed from the right-hand side in Java 7 is because it improves readability. By omitting type arguments on the right-hand side of a generic class instantiation, you can focus on what is important – working with objects rather than specifying types.
For example, compare these two code snippets:
Map<String, List<Integer>> map = new HashMap<>();
Map<String, List> map = new HashMap<String, List>();
The first snippet using diamond operator is more readable and concise compared to explicitly specifying type arguments in second snippet. This makes code easier to understand and maintain.
3. Compatibility with Older Code
An important consideration when introducing new features like Diamond Operator is backward compatibility with older codebases. By allowing developers to omit type arguments on generic class instantiations using diamond operator syntax, existing code can be easily migrated to newer versions without breaking compatibility.
This compatibility ensures that developers can take advantage of new language features without having to rewrite large portions of their existing codebase.
Other Languages Comparison
The concept of inferred or implicit typing is not unique to Java – many other programming languages also support similar features for reducing verbosity and improving readability.
C# Example:
var list = new List<string>();
var dictionary = new Dictionary<string, int>();
Kotlin Example:
val list: List = ArrayList()
val map: Map = hashMapOf()
TypeScript Example:
const list: Array = []
const map: { [key: string]: number } = {}
Rust Example:
let vec: Vec = Vec::new();
let hash_map: HashMap;
Groovy Example:
def list = []
def map = [:]
In all these languages (C#, Kotlin, TypeScript, Rust), inferred or implicit typing allows developers to write cleaner and more concise code by omitting explicit type declarations where they are not necessary.
In Conclusion,
The Diamond Operator introduced in Java 7 has been a valuable addition for reducing verbosity and improving readability when working with generics. The decision not to include it on right-hand side has been justified by benefits such as improved readability through implicit typing and better compatibility with existing codebases.
This feature aligns with trends seen in other programming languages where inferred or implicit typing is used to simplify syntax and make code more maintainable across different versions and platforms.