When debugging a Java application, dbx is in one of three modes:
When dbx is Java mode or JNI (Java Native Interface) mode, you can inspect the state of your Java application, including JNI code, and control execution of the code. When dbx is in native mode, you can inspect the state of your C or C++ JNI code. The current mode (java, jni, native) is stored in the environment variable jdbx_mode.
In Java mode, you interact with dbx using Java syntax and dbx uses Java syntax to present information to you. This mode is used for debugging pure Java code, or the Java code in an application that is a mixture of Java code and C JNI code or C++ JNI code.
In JNI mode, dbx commands use native syntax and affect native code, but the output of commands shows Java-related status as well as native status, so JNI mode is a “mixed” mode. This mode is used for debugging the native parts of an application that is a mixture of Java code and C JNI code or C++ JNI code.
In native mode, dbx commands affect only a native program, and all Java-related features are disabled. This mode is used for debugging non-Java related programs.
As you execute your Java application, dbx switches automatically between Java mode and JNI mode as appropriate. For example, when it encounters a Java breakpoint, dbx switches into Java mode, and when you step from Java code into JNI code, it switches into JNI mode.
dbx does not switch automatically into native mode. You can switch explicitly from Java or JNI Mode to native mode with the joff command, and from native mode to Java mode with the jon command.
If you interrupt execution of your Java application (for example, with a control-C), dbx tries to set the mode automatically to Java/JNI mode by bringing the application to a safe state and suspending all threads.
If dbx cannot suspend the application and switch to Java/JNI mode, dbx switches to native mode. You can then use the jon command to switch to Java mode so that you inspect the state of the program.