Java 8 new Feature method reference detailed introduction _java

Java 8 New Attribute method reference

For reference we are generally used in objects, and object references are characterized by: different reference objects can manipulate the same piece of content!

The Java 8 method reference defines four different formats:

1. Referencing static methods ClassName:: Staticmethodname
2. Reference object method:: MethodName
3. Referencing specific type methods: ClassName:: methodname
4. Reference construction Method: ClassName:: New

static method Reference Example

/**
 *   static method Reference
 * @param <P> Reference method parameter type
 * @param <R> Reference method return type *
* Functionalinterface
Interface funstaticref<p,r>{public

  R trantest (P p);

}



public static void Main (string[] args) {

    /
    *  static method reference: public static String valueof
    *   The valueof () method of the String is referred to as the Funstaticref#trantest method
    * *
    funstaticref<integer, string> funstaticref = string::valueof;
    String str = funstaticref.trantest (10000);
    System.out.println (Str.replaceall ("0", "9"));
}

Object Method Reference Example

/**
 *  Common method Reference
 * @param <R> Reference method return type */
@FunctionalInterface
interface Instanref<r >{Public

  R uppercase ();
}

public static void Main (string[] args) {
  
   *
   * Reference to Common method: Public String touppercase ()
   *
   /
   string STR2 = "I to You";
   Instanref<string> instanref = str2:: touppercase;
   System.out.println (Instanref.uppercase ());

}

Example of a specific type method reference

The reference to a particular method is more difficult to understand, and it refers to a common method, but the way it is referred to is: ClassName:: methodname

/**
 * References to specific methods
 * @param <P> * *
@FunctionalInterface
interface specificmethodref<p>{ public
  int Compare (P p1, p p2);
}

public static void Main (string[] args) {

   *
    * * Reference to a specific method public int compareTo (String anotherstring)
    *  Instead of defining an object before a method reference, it can be understood to define an object on a parameter!
    */
   Specificmethodref<string> specificmethodref = String:: compareTo;
   System.out.println (Specificmethodref.compare ("A", "B"));

   constructorref<book> constructorref = Book:: New;
   Book book = Constructorref.createobject ("Java", 100.25);
   SYSTEM.OUT.PRINTLN (book);
}

To construct a method reference sample

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) {

  /
   * * Construction Method Reference */
  constructorref<book> constructorref = Book:: New;
  Book book = Constructorref.createobject ("Java", 100.25);
  SYSTEM.OUT.PRINTLN (book);
}

In general, some of the new features of Java 8 have not been used extensively in the current project, but you will not be aware of the code for this Java 8 new feature until you learn it.

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