最病 E motivating example: Tracing Lass Trace Support t TraceSupport tatic int TRACELEVEL =0 tatic proteated Printstream stream null tatic proteated int callDepth =-1 static void init(Printstream s)[stream= si) traceEntry(String st (TRACELEVEL 0) return callDepth++ tEntering(str)i tatic void traceExit(String str) (TRACELEVEL 0)ret class Point( callDepth-- void set (int x, int yr printExiting(str) Trace Support. traceEntry(Pointset) this X =X this y=y Trace Support. traceExit(Point set); Institute of Computer Software 2021/1/27 Nanjing UniversityA motivating example: Tracing 2021/1/27 Institute of Computer Software Nanjing University 13 class Point{ void set (int x, int y){ TraceSupport.traceEntry(“Point.set”); this.x =x; this.y=y; TraceSupport.traceExit(“Point.set”); } }