Lecture 12 Runtime Management Last time 1 Parameter passing 2 Libraries 3 Public vs private Today 1 runtime stack management 2 variable initialization 3 function overloading rules 4 this CMSC 131 Fall 2007 Jan Plane adapted from Bonnie Dorr Call Stack Keeps track of variables Stack Frames Stack Operations push pop Eclipse can show the stack CMSC 131 Fall 2007 Jan Plane adapted from Bonnie Dorr 1 Initialization of Variables Summary Local Variables Parameters Instance Variables Static Variables CMSC 131 Fall 2007 Jan Plane adapted from Bonnie Dorr 2 Overloading Methods Two methods with the same name but distinguishable parameter types Terminology prototype public static void f int x float y signature f int float names of variables and the return type are not part of it Can t differ only in return type Can t differ only in types that can be implicitly promoted between widening conversion when choices are equal in amount of conversion CMSC 131 Fall 2007 Jan Plane adapted from Bonnie Dorr 3 Implicit Promotions On general assignments On parameters On return value CMSC 131 Fall 2007 Jan Plane adapted from Bonnie Dorr 4 Most SUBTLE example Consider overloading like this void f int x double y void f double a int b Three Calls f 3 10 0 f 7 7 5 f 3 7 CMSC 131 Fall 2007 Jan Plane adapted from Bonnie Dorr 5 this a reference to the current object Only makes sense in a non static method In an instance method this is the object that is assumed easy to refer to members data or methods using the assumed object difficult to refer to the whole object without having a name to call it Only use when needed using it all the time makes the code more difficult to read CMSC 131 Fall 2007 Jan Plane adapted from Bonnie Dorr 6
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