JDI

JDI stands for Java Debug Interface, a high-level API for building debugging tools for Java programs. It is part of the Java Platform Debugger Architecture (JPDA), alongside the low-level protocol JDWP (Java Debug Wire Protocol) and the native interface JVMTI. JDI provides a Java language API that debugger applications use to control and inspect a target VM without implementing protocol details.

The API enables connecting to a debuggee VM, configuring breakpoints, stepping through code, inspecting thread state and stack frames, and examining or modifying variables and fields. It supports both local and remote debugging through connectors such as LaunchingConnector and AttachingConnector to obtain a VirtualMachine instance.

JDI uses an event-based model. Debuggers receive events such as BreakpointEvent, StepEvent, MethodEntryEvent, and ClassPrepareEvent, and respond by issuing further requests or evaluating expressions in the context of stack frames.

Major development environments, including Eclipse, IntelliJ IDEA, and NetBeans, implement JDI to provide their debugging features. The API is designed to be platform-independent and hides the details of the underlying JDWP protocol, though performance and capabilities depend on the target VM and session configuration.