> ## Documentation Index
> Fetch the complete documentation index at: https://differens.ossl.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Java

> Semantic diffing for Java

## 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:

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

```java theme={null}
// 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.