java8 [a, lambda expression syntax]

Feature

Allow lambda expression parameter as a function of the method
lambda expression more concise

feature

Optional type declaration: do not need to declare the parameter type, the compiler can be unified identification parameter value.
The optional parameters in parentheses: a need to define the parameters in parentheses, but a number of parameters need to be defined parentheses.
Optional braces: if the body contains a statement, you do not need to use braces.
Optional return keyword: If the subject is only one expression that returns a value, the compiler will automatically return value, braces need to specify clear expression that returns a value

grammar

lambda expression consists of two parts [parameter list] -> [realize]

(parameters)->express 或 (parameters)->{express}

Expression syntax examples

　　@Test
     public  void test1 () {
         // 1. line of code 
        the Runnable runnable1 = () -> System.out.println ( "Hello" ); 
        the Runnable runnable2 = () -> { 
            System.out.println ( "Hello" ) ; 
        }; 
        // 2 lines of code 
        the Runnable runnable3 = () -> { 
            System.out.println ( "Hello" ); 
            System.out.println ( "Hello" ); 
            System.out.println ( "Hello" ) ; 
        }; 
        // 3. a parameter type may be ignored 
        x-> the System.out.println(x);
        (x) -> System.out.println (X); 
        (String X) -> System.out.println (X); 
        
        // or more parameters of type 4.2 can be ignored 
        (x, y) -> System.out.println (X + Y); 
        (X String, String Y) -> System.out.println (X + Y); 
        
        // 5. The return a line of code 
        () -> 5 ; 

        // 6 has multiple return lines 
        () - > {
             int A = 10 ;
             return A; 
        } 
    }

java8 [a, lambda expression syntax]

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