Smart Completion by IntelliJ - Detailed Review

IntelliJ IDEA’s Smart Completion

IntelliJ IDEA’s Smart Completion is a powerful feature that significantly enhances the coding experience by providing context-aware code suggestions. Here are the main features and how they work:

Type-Matching Completion

Smart Completion filters the suggestion list to show only the types applicable to the current context. This is particularly useful in situations such as:

• The right part of assignment statements
• Variable initializers
• `return` statements
• The list of arguments of a method call
• After the `new` keyword in an object declaration
• In chained expressions.

To invoke Smart Completion, you start typing and then press `Ctrl Shift Space`. This ensures that only relevant types are suggested, reducing the likelihood of errors and saving time.

Context-Aware Suggestions

Smart Completion analyzes the context of your code to suggest the most relevant classes, methods, fields, and variables. For example, when calling a method, it will suggest only the parameters that match the required parameter type. This feature is especially useful in XAML event handlers and other complex contexts.

Chain Completion

If you need to type a chain of method calls, such as `getModule().getProject()`, Smart Completion can help. By invoking Smart Completion twice, IntelliJ IDEA will scan the visible variables, fields, and methods and offer a chain that satisfies the expected type.

Static Fields and Methods

Smart Completion can also suggest static fields and methods. If you start typing the name of a static member and invoke Smart Completion, IntelliJ IDEA will provide the correct completion and even offer to import the member statically if needed.

Data Flow Analysis

IntelliJ IDEA uses data flow analysis to guess the type of a variable at runtime and provide completion based on this type. This feature automatically adds class casts when necessary, making the coding process more efficient and accurate.

Parameter Info

When using Smart Completion, IntelliJ IDEA shows parameter info for every overloaded method or constructor. It highlights the best match for the parameters already typed, helping you choose between overloaded options and compare your input with the expected parameters.

Middle Matching

Smart Completion allows you to type any part of an identifier, not just from the beginning. This feature, known as “middle matching,” significantly improves performance by suggesting correct completions even if you remember only a part of the name.

AI Integration

While the primary functionality of Smart Completion is based on context analysis and type matching, IntelliJ IDEA also integrates machine learning to rank completion suggestions. This feature, known as “Machine Learning Completion Ranking,” prioritizes suggestions based on choices made by other users in similar situations. The data is collected locally and does not expose any user information. You can enable this feature in the settings under `Editor | General | Code Completion`.

Completion Tips and Tricks

Smart Completion can be further refined by accessing the completion settings directly from the completion popup. You can narrow down the suggestion list by typing any part of a word or invoking code completion after a dot separator. This makes the use of wildcards unnecessary and allows for more precise completion suggestions.

Conclusion

In summary, IntelliJ IDEA’s Smart Completion is a powerful tool that leverages context-aware suggestions, type matching, and data flow analysis to provide efficient and accurate code completion. While it does not rely heavily on AI for its core functionality, the integration of machine learning for ranking suggestions enhances its usability and relevance.