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This article will explain in detail what are the attention items of java polymorphism for you. The editor thinks it is very practical, so I share it with you for reference. I hope you can get something after reading this article.

Show the polymorphism package test;// parent class reference, point to the instance of (different subclasses), call the same instance method name, the calling program is not / the same. Inheritance is the basis on which polymorphism can be realized. Public interface test1 {void shout ();} package test;public class test2 implements test1 {public void shout () {System.out.println ("1111");}} package test;public class test3 implements test1 {public void shout () {System.out.println ("222222");}} package test;public class test4 {public static void main (String [] args) {test1 ts = new test2 (); ts.shout () Test1 ts1 = new test3 (); ts1.shout ();}} the basis of polymorphism and restrictions on package test;public class test5 {public static void speak () {System.out.println ("speak:");}} package test;public class test6 extends test5 {public static void speak () {System.out.println ("11111") } / / Polymorphism is based on inheritance and rewriting / / Polymorphism is limited to instance methods public static void main (String [] args) {test5 ts1 = new test5 (); test6 ts = new test6 (); ts1.speak (); ts.speak ();}} object type conversion package test;public class test7 {public void speak () {System.out.println ("speak:") }} package test;public class test8 extends test7 {@ Override public void speak () {System.out.println ("1111");}} package test;public class test9 extends test7 {@ Override public void speak () {System.out.println ("22222");} protected void action () {System.out.println ("tapping code");}} package test Public class test10 {public static void main (String [] args) {/ / upward type conversion implicitly safe / / treat test8 objects as test7 types with test7 ts = new test8 (); ts.speak (); / / cast shows unsafe test7 ts1 = new test9 (); test9 ts2 = (test9) ts1; ts2.speak () / / how to avoid the unsafe interface-oriented programming caused by forced type conversion plus instanceof test7 ts3 = new test8 (); test7 ts4 = null; if (ts3 instanceof test9) {ts4 = (test9) ts3;} if (ts3 instanceof test8) {ts4 = (test8) ts3;} ts4.speak ();}} object class

Common methods of the Object class can also be overridden by package test;public class test11 {public void speak () {System.out.println ("speak:");}} package test;public class test12 {public static void main (String [] args) {test11 ts = new test11 (); ts.speak (); / / returns the string representation of the object System.out.println (ts.toString ()) / / returns the hash code value of the object System.out.println (ts.hashCode ());}} anonymous inner class package test;public interface test13 {void speak ();} the class defined in the package test;public class test14 {/ / class is called the inner class (Inner Class), and the inner class is a member of the outer class. / / Java inner classes can be divided into member inner classes, method inner classes and anonymous inner classes. Class person implements test13 {@ Override public void speak () {System.out.println ("111111");} public static void main (String [] args) {class person1 implements test13 {@ Override public void speak () {System.out.println ("2222222222") You can use anonymous inner classes to implement the interface. The so-called anonymous inner class is the inner class without a name. On the surface, it seems to have a name, but in fact that is not its name. When an anonymous inner class is used in a program, an object of that class is often created directly where the anonymous / / inner class is defined. New test13 () {@ Override public void speak () {System.out.println ("3333333");}. Speak () }} this is the end of this article on "what are the java polymorphic attention items?". I hope the above content can be helpful to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

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