Java - Differens

Java extractor

The Java extractor maps tree-sitter Java CST nodes to canonical concepts. Class and method names come from the standard name field; variable names are recovered from the declarator.

Detected concepts

tree-sitter node type	Canonical concept
`class_declaration`	Class
`interface_declaration`	Interface
`enum_declaration`	Enum
`method_declaration`	Method
`constructor_declaration`	Constructor
`package_declaration`	Namespace
`import_declaration`	Import
`field_declaration`	Variable
`local_variable_declaration`	Variable
`formal_parameters`	Parameters
`decimal_integer_literal`	integer_literal
`method_invocation`	CallExpression

Example

Renaming a method:

// old.java
class Counter { int total(int n) { return n + 1; } }

// new.java
class Counter { int sum(int n) { return n + 1; } }

Running differens old.java new.java:

~ renamed method `total` to `sum` in class `Counter`

Known limitations

Lambda bodies are diffed structurally; a lambda extracted to a named method reports as an addition plus a body change, not an extraction.
Annotations are structure: adding an annotation reports as an insert, not an “annotated” action.