The Debug function of a Java program is realized through the debugger in the IDE and JVM. The following is the basic process of implementing Java Debug in IDEA and other IDEs:
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Start JVM: Start the JVM in Debug mode, and configure the JVM's debugging port and breakpoint information, etc. at the same time.
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Connect to JVM: IDE establishes socket connection with JVM, sends debugging request to JVM in Debug mode, and information that needs to be passed to JVM. The JVM accepts these requests and returns response information to the IDE.
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Receive events: After the IDE connects to the JVM, it will monitor the event information from the JVM, such as thread suspension, variable change, etc.
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Breakpoint setting: The IDE can set a breakpoint on the line of code that needs to be debugged, and send the breakpoint information to the JVM. When the code runs to the set breakpoint, the JVM will suspend the thread and notify the IDE.
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Debugging information: IDE obtains debugging information from JVM through socket, including stack trace, variable value, etc., and displays these information in the debugging view.
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Debugging control: IDE monitors the user's operations, such as single-step execution, jumping to the next breakpoint, observing variables, etc., and sends corresponding instructions to the JVM to control the execution status of the program.
The above is the basic flow of Java Debug. Through the Debug function, we can easily locate problems in the code, find out exceptions, solve bugs, and so on.