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}classStudentextendsperson2{}three, comparable interface: A method (Comparato)int CompareTo (T o)Compares this object to the specified object for sorting.
The object is smaller than the specified object and returns a negative integer (-1);
The object is equal to the specified object and returns a 0 (0);
The object is larger than the specified object and returns a positive integer (1);
Example: PackageCollectiontext;Importjava
letter (sometimes multiple generic types with numbers, such as T1,T2), such as many container collections using E, representing element (elements), and map with K for key keys,v to represent values.Two practical applications:(1) Creating a Java file for interface ParentinterfacePackage Edu.tju.cs;public interface parentinterface(2) Creating
Why generics are required?Imagine that you need a simple container class, or a handle class, for example to store an apple basket, and you can do so simply:fruit{}fruit{}apple apple; public void set (this.apple;}} Such a simple basket would be implemented, but the problem is that it only stores apples, and then there is another pile of fruit, and you have to implement containers for these fruit classes sep
defaultsInterface does not contain a constructor methodAbstract classes can contain construction methods, which are constructed not to create objects, but to be called by their subclasses to complete the initialization operation.A class can have at most one direct parent class, including abstract classesA class can implement multiple interfaces1.8instanceof keywordsTwo reference variables of the same type may behave differently when the same method i
traverse and select objects in a sequence, and the developer does not need to know the underlying structure of the sequence . Iterators are often referred to as "lightweight" objects because they are less expensive to create.Iterators in the collectionSince there are many different sets in Java, we want to have a uniform way to get its value, so we have an iterator.Interface iterator: There are two abstract methods
Boolean Hasnext () determi
The concept of fast sorting algorithmfast sorting is generally based on recursive implementations. The idea is this:1. Select a suitable value (ideally, the value is the best, but the first value of the array is generally used in the implementation), called "pivot" (pivot).2. Based on this value, the array is divided into two parts, the smaller one on the left and the larger on the right.3. To be sure, such a round down, this pivot position must be in the final position.4. Repeat the above proce
specific type A and B, such asNumber is not relatedto Integer, myclassmyclass The common parent class of myclassObject. When there is a relationship between parameter types, how to establish a relationship between two sub-generic classes like subtypes, refer to wildcard characters and subtypes.Generic class and sub-typeYou can either extend or implement it by using a subclass or interface. The relations
Java generics and java generics
1. OverviewBefore introducing the fan type, Java types include the original type and the complex type. The complex types include arrays and classes. After the fan type is introduced, a complex typeYou can split it into more types in detail.For
Must the subclass of the interface implement all the methods of the interface?Must the subclass of the interface implement all the methods in the interface? Answer: No. The reasons are as follows:If the subclass is a non-abstract
the name of the inner class is superfluous, soThe anonymous inner class is used.3, how to implement anonymous internal class? The implementation of an anonymous inner class is very simple, such as having an interface Interface a{public void Method (); At this point you can write a statement like the following to get the implementation class of
.real_name=" + r2.get ("real_name") + ", r2.email="+ r2.get ("email") + ", r2.name=" + r2.get ("name"));}}In the spirit of the principle of sharing resources, welcome all friends on this basis to improve and further share, let us achieve more elegant. If you have any questions and need further communication can add my QQ 1922003019 or directly send QQ mail to me to communicateSea 20150608 China: Guangzhou: VIPBUGZILLA4 XMLRPC Interface API call Implem
of the Externalizable instance class is that it can be written to the serialized stream, which is responsible for saving and recovering the instance content. If you want to fully control the flow format and content of an object and its super-type, it implements the Writeexternal and Readexternal methods of the Externalizable interface. These methods must be explicitly reconciled with the superclass to hold their state. These methods are implemented i
Learning GoalsMastering the use of generic interfacesMastering the definition and use of generic methodsMastering the use of generic arraysMastering nested settings for genericsall of the previous operations are directly using generic operations in the class, and for Java, generics can be defined and used directly in the interface. Defining generic Interfacesafte
for common methods. This generic class is applicable to all classes or partial classes, generally, it is used with a partial classification. Some restrictions apply to these classes. generic classes do not care about the specific types of classes, but whether they can execute a certain method!
This is the "potential type mechanism ". Therefore, generic classes generally require the parameter type to implement a method or have a method. The i
use of rewriting the simple version ArrayListUse generic code as follows:packagejavabasic.generic;/*** Simple Version arraylist*/classarrlistIf you want to useArrlist.add ("1");Will find:This is when generics are being used, and there is no need to cast the property Get method. In fact, Java generics are just a compile-time concept, because the type will be era
1. interface is not just an extremely abstract class, because it allows people to create a class that can be transformed up to multiple base types to implement a class similar to C ++Multiple inheritance variants.
2. Like a class, you can add a public keyword before the interface keyword (but only for this interfaceSame nameIs defined in the file), or does not ad
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