Lambda表达式

明确指出参数类型

(int a, int b) -> a + b;

代码多余一行，不能省略{}以及最后一行的return

(int a, int b) -> {int c = a + b; return c;}

Lambda1 lambda = (a, b) -> a + b;

interface Lambda1{

int op(int a, int b);

}

函数对象-方法引用

Math::max    =  (int a, int b) -> Math.max(a, b);

Student::getName = (Student stu) -> stu.getName();

System.out::println = (Object obj) -> System.out.println(obj);

Student::new =  () -> new Student();

练习

1）判断语法正确性

interface Lambda1 {

int op(int a, int b);

}

interface Lambda2{

void op(Object obj);

}

1. Lambda1 lambda = a, b -> a-b  正确 错误，参数多于一个需要用括号，Lambda1 lambda = (a, b) -> a – b;
2. Lambda1 lambda = (a, b) -> c * b; 正确 正确
3. Lambda1 lambda = (int a, b) -> a + b; 错误 错误
4. Lambda2 lambda = Object a -> Systemc.out.println(a); 正确 错误 (Object a) -> Systemc.out.println(a); 或者 a -> System.out.println(a);
5. Math:random        ()->Math.random();
6. Math::sqrt      (double number) -> Math.sqrt(number);
7. Student::getName;        (Student stu) -> stu.getName();
8. Student::setName;        (Studnet stu, String newName) -> stu.setName(newName);
9. Student::hashCode;        (Student stu) -> stu.hashCode();
10. Student::equals;        (Sutdnet stu, Object o) -> stu.equals(o);

假设已有对象 Student stu = new Student(“张三”);

1. stu::getName