how to achieve polymorphism in java

First, Package:　　internal can encapsulate their own implementation details, so that the information is hidden from other categories of destruction;　　 The division of labor between the various classes is clear, other classes do not need to care about the implementation details, class changes in the details, other classes do not need to make changes;Second, Inherit:Derive new classes from existing classes in order to achieve the purpose of function and

, the lookup process ends, and if it does not, the Java.lang.IllegalAccessError exception is returned. Otherwise, follow the inheritance relationship from the bottom up to the next step in the search and validation process for each of the parent classes in C . 2. If the appropriate method is never found, the Java.lang.AbstractMethodError exception is thrown. It is precisely because the invokevirtual directive is such an execution process that it explains why the implementation of

(Parent p) { - //now output the methods in the parent class in P.grow (); - //type judgment on the objects that have been transformed and then make the corresponding forced transformation to if(pinstanceofSon) { + //determine which class is on the top of the transformation object and then make the next transformation -Son s=(Son) p; the //calling a method in a subclass * S.play (); $}Else if(pinstanceofdaughter) {Panax Notogins

does show (B obj) exist in Class A? It doesn't exist at all! So this is not a valid sentence here? So is this the wrong sentence? Not too! In fact, this sentence also implies that this sentence: it still has to follow the inheritance chain to invoke the priority of the method to confirm. So it will find show (a obj) in Class A, and the method in Class B is called because B overrides the method, otherwise the method in Class A is called.Therefore, the principle of polymorphic mechanism is summar

Polymorphism has three-factor inheritance, method overrides, parent-class references to child-class objectsPolymorphism can be understood as two parts: one is compile, one is runtimeCompile-time: Define rules; Run time: implement this rule specifically.Compile time: The parent class is coerced into a subclass without error; Runtime: First go to the parent class to find this method and then see if the subclass has not overridden this method if it does

Polymorphic:1 Meaning: 1.1 References of the same type point to different objects are polymorphic that have different implementations-----behavior 1.2 When the same object is shaped into different types, there are different functions--------the polymorphism of the object 2 Up Styling:-----Automatic type conversion 2.1 Super-type references to objects of derived classes 2.2 Types that can be shaped are: Super Class + interface imple

Polymorphism: A variable of the same type, when the same method is called, presents many different behavioral characteristics, which is polymorphic.1. A reference variable can only invoke the method that its compile-time type has when it is compiled, but the runtime executes the method it has with the run-time type , so when writing Java code. A reference variable can only invoke methods contained in the cl

"abstract Method" in Java is equivalent to the pure virtual function in C ++. 13. constructors do not have multi-state rows (they are actuallyStatic Method, But the static statement is implicit ). 14. If a dynamic binding method is called within the constructor, the member manipulated by the called method may not be initialized (It may cause some difficult-to-discover hidden errors.). Example: Class glyph {void draw () {system. out. println ("glyph

1. EncapsulationHiding the state information of an object inside an object does not allow the external program to access the information inside the object directly, but rather through the methods provided by the class to implement operations and access to internal information, that is, the set and get methods.There are two main meanings:(1) Hide the hidden.(2) exposing the exposure.2. InheritanceSubclasses inherit the behavior of the parent class.3. polymorphicThere are two types of

construction methods can be overloaded.(2) Definition: Refers to multiple methods in the same class that can be defined with the same name but with different parameters. The corresponding method is selected according to the different parameter tables when calling.(3) Two with three different: the same class, the same method name, parameter list parameters of the type, number, order of different.(4) Only the return value type does not constitute an overload! Only parameter names are different an

eat(food f){ System. Out. println("I'm a dog, I'm eating" + F. ) Getfood()); } } Food and its sub-categories Class Food { public String getfood(){ return "things"; } } Class Fish extends food{ public String getfood(){ return "fish"; } } Class Bone extends food{ public String getfood www.zenmebanw.com (){ return "Bone"; } } Master Class Class Master{ public void feed(Animal A, food f){ An

Before our article on the Java Packaging and inheritance, encapsulation, and did not reflect the strength of the package, but also carefully use encapsulation. Because the package is not yet associated with polymorphism, there is no way to see the upside of the transformation.Polymorphism means that the same behavior has many forms of expression. The same method produces various results depending on the cal

------ Multi-state of object-oriented One: The concept of polymorphismThe meaning of polymorphism in practice is that different objects have the same general contour or shape, but the process of concrete execution is quite distinct. Example: Drivers are aware of the "brakes when they encounter a red light" when driving, which is specific to what the driver is driving.Model of the car is irrelevant, all cars have the same general profile or form of bra

Sonclass extends fatherclass{public void first_function () {System.out.println ("Sonclass::first_fun Ction "); } public void Second_function () {System.out.println ("sonclass::second_function"); } public void Third_function () {System.out.println ("sonclass::third_function"); }}In the C + + language, because its methods are not dynamically bound by default, that is, not late binding. To achieve the flexibility of a method with late-bound pro

[Java SE] How to Use Java to achieve direct selection and sorting, and sejava to achieve sorting Abstract: Direct selection of sorting is a kind of sorting, but its sorting algorithm is faster than Bubble sorting, because its algorithm is relatively simple, therefore, it is also suitable for beginners to learn and mast

. Money =Money ; } PublicMaster (String name,intMoney ) { This. name=name; This. money=Money ; } /** The owner feeds the pet*/ Public voidFeed (Pet Pet) {pet.eat (); } //The owner feeds the dog . Public voidFeed (dog dog) {dog.eat (); } //The host feeds Penguin . Public voidFeed (Penguin pgn) {pgn.eat (); } }Package cn.yy.test01; Public classTest { Public Static voidMain (string[] args) {//TODO auto-generated Method StubDog dog=NewDog ("ev

][AA][BB]. One of the knowledge points examined here is that the reference to the subclass refers to the parent class type to see if you understand it in depth.In Java inheritance, the attribute is not polymorphic, only the method supports polymorphism. You might think that the method does not support polymorphism then A.S will output "[AA]". Actually when execut

One.Previous examples of lifting, Animal a=new Cat (); When the animal's reference points to the Cat object, the Cat object has two forms. Either the shape of the cat or the form of an animal. At this time, the Cat object will have polymorphism. This is an elevation when the parent class points to a child object. This is called upward transformation. Turned into an animal type. If you need subclasses to do this, you need to move down.Now let's take an

not need to retrieve the method table at run time, can improve the efficiency of code execution. In Java, methods that are modified by static or private are implicitly declared final, because dynamic binding has no meaning.Because dynamic binding consumes resources and is not necessary in many cases, some programmers think that unless there is sufficient reason to use polymorphism, all methods should be fi

type: ToString Method Form: Public String toString (); To convert a string to an object of a wrapper class: Example: Public Integer (String s); Convert a string to data of the base data type: valueof (String) method or Parsetype () static method 4. After the JDK5.0 version, the Java Virtual Machine supports the automatic boxing, unpacking mechanism Auto-Boxing: Automatically encapsulates data of a basic data type as the approp