/**
* 对象::实例方法名
* 注意：Lambda体中的方法的参数列表和返回值要与函数式接口中抽象方法的参数列表和返回值类型一致
*/
@Test
public void test1(){PrintStream ps = System.out;Consumer<String> con = (x) -> ps.println(x);PrintStream ps1 = System.out;Consumer<String> con1 = ps1::println;Consumer<String> con2 = System.out::println;con2.accept("1234");//1234
}@Test
public void test2(){User user = new User();Supplier<String> sup = () -> user.getName();String str = sup.get();System.out.println(str);//nullSupplier<Integer> sup2 = user::getAge;Integer age = sup2.get();System.out.println(age);//null
}

/**
*  类::静态方法名
*  注意：Lambda体中的方法的参数列表和返回值要与函数式接口中抽象方法的参数列表和返回值类型一致
*/
@Test
public void test3(){//lambda的方式Comparator<Integer> com = (x,y) -> Integer.compare(x,y);//新的方式Comparator<Integer> com2 = Integer::compare;
}/**
* 类::实例方法名
*/
@Test
public void test4(){BiPredicate<String,String> bp = (x,y) -> x.equals(y);//只有当x是实例方法的调用者，y是这个实例方法的参数时可以按如下写法BiPredicate<String,String> bp2 = String::equals;
}

二、构造器引用

/**
* 构造器引用
* 语法格式：ClassName:new
*/
@Test
public void test5(){Supplier<User> sup = () -> new User();//构造器引用的方式Supplier<User> sup2 = User::new;User user = sup2.get();System.out.println(user);//User{name='null', age=null}
}/**
* 构造器引用2,一个参数
*/
@Test
public void test6(){Function<String,User> fun = (x) -> new User("zs");Function<String,User> fun2 = User::new;User user2 = fun2.apply("ls");System.out.println(user2);//User{name='ls', age=null}
}/**
* 构造器引用3,两个参数
*/
@Test
public void test7(){BiFunction<String,Integer,User> bf = User::new;User user = bf.apply("zs", 22);System.out.println(user);//User{name='zs', age=22}
}

/**
* 数组引用
* 语法格式：Type::new;
*/
@Test
public void test8(){Function<Integer,String[]> fun = (x) -> new String[x];String[] args = fun.apply(5);System.out.println(args.length);//5//数组引用Function<Integer,String[]> fun2 = String[]::new;String[] args2 = fun2.apply(10);System.out.println(args2.length);//10
}

public class User {String name;Integer age;//默认构造函数public User() {}//一个参数的构造函数public User(String name) {this.name = name;}//两个参数的构造函数public User(String name, Integer age) {this.name = name;this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}@Overridepublic String toString() {return "User{" +"name='" + name + '\'' +", age=" + age +'}';}
}