Java 8 new features-4 method reference, new features-4

Java 8 new features-4 method reference, new features-4

ForReferenceIn general, we use the object, and the characteristics of object reference are:Different referenced objects can operate on the same content.!

Java 8 method reference defines four formats:

• • ReferenceStatic MethodClassName: staticMethodName
  • ReferenceObject Method: Object: methodName
  • ReferenceMethods of Specific Types: ClassName: methodName
  • ReferenceConstructor: ClassName: new

 

• Static Method reference example

  • /*** Static method reference * @ param <P> parameter type of the referenced method * @ param <R> return type of the referenced method */@ FunctionalInterfaceinterface FunStaticRef <P, r> {public R tranTest (P p);} public static void main (String [] args) {/** static method reference: public static String valueOf * references the String valueOf () method to FunStaticRef # tranTest Method */FunStaticRef <Integer, String> funStaticRef = String: valueOf; String str = funStaticRef. tranTest (10000); System. out. println (str. replaceAll ("0", "9 "));}

     

     

• Object MethodReference example

  • /*** Common method reference * @ param <R> the return type of the referenced method */@ FunctionalInterfaceinterface InstanRef <R> {public R upperCase ();} public static void main (String [] args) {/** reference of common methods: public String toUpperCase () **/String str2 = "I see you "; instanRef <String> instanRef = str2: toUpperCase; System. out. println (instanRef. upperCase ());}

     

• Example of reference to a specific type of method
  • 　　The reference of a specific method is hard to understand. It references a common method, but the reference method is: ClassName: methodName
  • 　　

    /*** Reference of a specific method * @ param <P> */@ FunctionalInterfaceinterface SpecificMethodRef <P> {public int compare (P p1, P p2 );} public static void main (String [] args) {/** reference of a specific method public int compareTo (String anotherString) * compared with the previous one, objects do not need to be defined before a method is referenced, it can be understood that the object is defined on the parameter! */SpecificMethodRef <String> specificMethodRef = String: compareTo; System. out. println (specificMethodRef. compare ("A", "B"); ConstructorRef <Book> constructorRef = Book: new; Book = constructorRef. createObject ("Java", 100.25); System. out. println (book );}

     

• Constructor reference example
  • 　　

    Class Book {private String title; private double price; public Book () {} public Book (String title, double price) {this. price = price; this. title = title ;}@ Override public String toString () {return "Book {" + "title = '" + title +' \ ''+ ", price = "+ price + '}';}}
    
    Public static void main (String [] args) {/** constructor reference */ConstructorRef <Book> constructorRef = Book: new; Book book = constructorRef. createObject ("Java", 100.25); System. out. println (book );}

     

 

In general, some new features of Java 8 have not been widely used in the current project, but after learning it, I will not see the code of this new Java 8 feature and will be wrong!