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# Java™ java.lang.instrument Package

The `java.lang.instrument` package provides a Java™ programming language API for tools to instrument Java programming language applications -- for example, to monitor them or collect performance information. Tools use `java.lang.instrument` to modify the class file that defines a class -- generally, by inserting into the byte-code of methods additional byte-code which will perform the instrumentation.

`java.lang.instrument` was introduced in JDK™ 5.0.

## API Specification

- java.lang.instrument Package (package description)

## API Enhancements

- See the API Enhancements in JDK 6 - An annotated list of API changes between the 5.0 and 6 releases.

## More Information

- Java Virtual Machines Tool Interface - a native interface which can also perform instrumentation.
- `java.lang.management` package - the monitoring and management package, often useful with instrumentation.

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