java 基本语法（十七）Lambda （四）构造器引用与数组引用

1.构造器引用格式：
类名::new

2.构造器引用使用要求：
和方法引用类似，函数式接口的抽象方法的形参列表和构造器的形参列表一致。抽象方法的返回值类型即为构造器所属的类的类型

3.构造器引用举例：

//Supplier中的T get()

   //Employee的空参构造器：Employee()

   @Test

   public void test1(){

       Supplier<Employee> sup = new Supplier<Employee>() {

           @Override

           public Employee get() {

               return new Employee();

           }

       };

       System.out.println("*******************");

       Supplier<Employee>  sup1 = () -> new Employee();

       System.out.println(sup1.get());

       System.out.println("*******************");

       Supplier<Employee>  sup2 = Employee :: new;

       System.out.println(sup2.get());

   }

//Function中的R apply(T t)

   @Test

   public void test2(){

       Function<Integer,Employee> func1 = id -> new Employee(id);

       Employee employee = func1.apply(1001);

       System.out.println(employee);

       System.out.println("*******************");

       Function<Integer,Employee> func2 = Employee :: new;

       Employee employee1 = func2.apply(1002);

       System.out.println(employee1);

   }

//BiFunction中的R apply(T t,U u)

   @Test

   public void test3(){

       BiFunction<Integer,String,Employee> func1 = (id,name) -> new Employee(id,name);

       System.out.println(func1.apply(1001,"Tom"));

       System.out.println("*******************");

       BiFunction<Integer,String,Employee> func2 = Employee :: new;

       System.out.println(func2.apply(1002,"Tom"));

   }

4.数组引用格式：
数组类型[] :: new

5.数组引用举例：

//Function中的R apply(T t)

@Test

public void test4(){

    Function<Integer,String[]> func1 = length -> new String[length];

    String[] arr1 = func1.apply(5);

    System.out.println(Arrays.toString(arr1));

    System.out.println("*******************");

    Function<Integer,String[]> func2 = String[] :: new;

    String[] arr2 = func2.apply(10);

    System.out.println(Arrays.toString(arr2));

}

巴特西

java 基本语法（十七）Lambda （四）构造器引用与数组引用

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