Discussion 5: Inheritance and Midterm Review Christine Zhou Agenda Announcements Inheritance Practice 4. Midterm Review on Worksheet 2. Reduce on Worksheet Announcements Field hiding is in scope! Same as static lookup Sorry for the mix-up. We’ll go over this today Midterm is tomorrow 8-10PM. Room assignments on Piazza Go to right rooms! Best of luck! HW3 is due Friday 11:59PM Get started on the project! Discussion survey: tinyurl.com/disc5cz Inheritance Rules For non-static methods: During compilation: If static type has the method, it compiles. Otherwise check parent, parent… Compile time error if no more parent and still haven’t found the method. During runtime: Run the method in the dynamic type. Otherwise check parent, parent... For static method: During compilation: Same as non-static During runtime: Run the method found during compilation (don’t look at the dynamic type!) Always look at the dynamic type when running methods, unless the method is static! For fields: Use same procedures as static method lookup Look in the static type for the field and use the field that you eventually find Field Hiding If you have a variable of the same name in the static and dynamic type, then this is called “field hiding/shadowing”. It’s possible for the field in the static type to “hide/shadow” the field in the dynamic type. Field hiding is not good practice! Example public class Animal { public String x = “Animal”; public static void staticM() { System.out.println(“A static”); } public class Dog extends Animal { public String x = “Dog”; public static void staticM() { System.out.println(“D static”); } public void nonStaticM() { System.out.println(“A public void nonStaticM() { nonStatic”); System.out.println(“D } nonStatic”); public static void m1(Animal a) { } System.out.println(“A m1”); a.nonStaticM(); } } } public class Runner { public static void main(String[] args) { Animal a = new Dog(); System.out.println(a.x); a.nonS

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