一、lambda表达式的含义
Lambda 表达式是 Java 8 引入的一种简洁的语法,用于表示匿名函数或传递行为。它使得我们可以更简洁地表达代码中的行为和函数逻辑,特别是在使用函数式接口时(如 Consumer
二、基本的写法
interface Inter1 {void fun1();
}interface Inter2 {void fun1(String s);
}interface Inter3 {String fun1(String s1, String s2);
}public class LambdaDemo {public static void main(String[] args) {/*** 场景1*///无参数,无返回值
// show1(()->{
// System.out.println("好好学习,天天向上!");
// });// 如果方法逻辑体只有一行的时候,可以将大括号省略
// show1(()-> System.out.println("好好学习,天天向上!"));/*** 场景2*/// 有一个参数,无返回值
// show2((String s)->{
// System.out.println(s+": 江川");
// });// 左边的参数类型可以省略不写, jvm会做自动类型上下文推断
// show2((s) -> System.out.println(s + ": 江川"));// 若只有一个参数,小括号可以省略不写
// show2(s -> System.out.println(s + ": 江川"));/*** 场景3*///有两个以上的参数,有返回值,并且 Lambda 体中有多条语句
// show3((String s1,String s2)->{
// return s1+"-数加-"+s2;
// });// 若Lambda 体中只有一条语句,return和大括号都可以省略不写
// show3((s1, s2) -> s1 + "-数加-" + s2);}public static void show3(Inter3 inter3) {System.out.println(inter3.fun1("hello", "world"));}public static void show2(Inter2 inter2) {inter2.fun1("hello");}public static void show1(Inter1 inter1) {inter1.fun1();}
}
三、具体实例
1.先创建一个Staff类,里面有基本的成员
public class Staff {private String id;private String name;private int age;private int salary;public Staff() {}public Staff(String id, String name, int age, int salary) {this.id = id;this.name = name;this.age = age;this.salary = salary;}public String getId() {return id;}public void setId(String id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public int getSalary() {return salary;}public void setSalary(int salary) {this.salary = salary;}@Overridepublic String toString() {return "Staff{" +"id='" + id + '\'' +", name='" + name + '\'' +", age=" + age +", salary=" + salary +'}';}
}
2.进行测试使用lambda表达式
1.Staff类同上,这里就不重复写了
2.编写接口
public interface FilterStaff {boolean fun(Staff staff);
}
3.案例
import java.util.ArrayList;import java.util.List;public class StaffDemo1 {public static void main(String[] args) {ArrayList<Staff> list1 = new ArrayList<>();list1.add(new Staff("sj1001","彭于晏",23,30000));list1.add(new Staff("sj1002","吴彦祖",13,10000));list1.add(new Staff("sj1003","胡歌",21,24000));list1.add(new Staff("sj1004","章若楠",18,26000));list1.add(new Staff("sj1005","杨幂",26,35000));//需求:过滤出薪资大于20000的人的信息List<Staff> list2= FilterWithCollection(list1,s-> s.getSalary()>20000);for (Staff staff : list2) {System.out.println(staff);}}public static List<Staff> FilterWithCollection(List<Staff> staff,FilterStaff filterStaff){ArrayList<Staff> staff1 = new ArrayList<>();for (Staff staff2 : staff) {if(filterStaff.fun(staff2)){staff1.add(staff2);}}return staff1;}
}