JAVA入门学习 — 多态（预置函数接口）

Supplier：生产型接口（供给型），内有抽象方法—T get();

没有参数有返回值类型：

 @Test
    public void test(){
        Supplier stringSupplier = () -> {
            return "伟大的祖国";
        };
       String person = stringSupplier.get();
        System.out.println(person);
    }

UnaryOperator<>函数

一个参数有返回值类型：

@Test
    public void test01(){
        UnaryOperator unaryOperator = (n)->{
            return 2*n+1;
        };
        Integer num = unaryOperator.apply(2);
        System.out.println(num);
    }

BinaryOperator<>函数

两个参数有返回值类型：

 @Test
    public void test03(){
        BinaryOperator binaryOperator = (x,y)->{
            return x*y;
        };
        Integer num = binaryOperator.apply(5,6);
        System.out.println(num);
    }

Consumer：消费型接口，内有抽象方法—void accept(T t)

一个参数没有返回值类型：

 @Test
    public void test04(){
        Consumer consumer = (name)-> System.out.println(name);
        consumer.accept("孙悟空");
    }

Function：函数型接口，内有抽象方法—R apply(T t)

一个参数一个返回值类型（会比较两个函数给出不同结果）：

@Data
@NoArgsConstructor
@AllArgsConstructor
public class EmpVo {
    private String account;
    private String password;
    private String nickname;
}

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Emp {
    private String account;
    private String password;
    private String nickname;
    public Emp(String account,String password){
        this.account = account;
        this.password = password;
    }
}

@Test
    public void test05(){
        Emp[] emps = new Emp[5];
        for (int i = 0; i < emps.length; i++) {
            emps[i] = new Emp("emp"+(i+1),"123456","emp"+(i+1));
        }
        Emp login = new Emp("emp2","123456");
        Function function = (emp)->{
            for (Emp db:emps
                 ) {
                if(db.getAccount().equals(emp.getAccount()) && db.getPassword().equals(emp.getPassword())){
                  return new EmpVo(db.getAccount(), db.getPassword(), db.getNickname());
                }
            }
            return null;
        };
        EmpVo empVo = function.apply(login);
        if (empVo == null) {
            System.out.println("账号或密码错误");
        }else{
            System.out.println("员工"+ empVo.getNickname()+"登录");
        }
    }

Predicate：断言型接口，内有抽象方法—boolean test(T t)

 @Test
    public void test08() {
        Emp[] emps = new Emp[5];
        for (int i = 0; i < emps.length; i++) {
            emps[i] = new Emp("emp" + (i + 1), "123456", "emp" + (i + 1));
        }
        Emp login = new Emp("emp2", "123456");
        Predicate predicate = (emp) -> {
            for (Emp db : emps
            ) {
                if (db.getAccount().equals(emp.getAccount()) && db.getPassword().equals(emp.getPassword())) {
                    return true;
                }
            }
            return false;
        };
        boolean test = predicate.test(login);
        if (test) {
            System.out.println("登陆成功");
        } else {
            System.out.println("登陆失败");
        }

    }

JAVA入门学习 — 多态（预置函数接口）

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