调试Java 8过滤器

Question

我有雇员对象

public class Employee {

    public Employee(Integer id, Integer age, String gender, String fName, String lName) {
        this.id = id;
        this.age = age;
        this.gender = gender;
        this.firstName = fName;
        this.lastName = lName;
    }

    private Integer id;
    private Integer age;
    private String gender;
    private String firstName;
    private String lastName;

我有两个谓词

public static Predicate<Employee> firstNameLike(final String name) {
        return p -> p.getFirstName().contains(name);
    }


    public static Predicate<Employee> isAdultFemale() {
        return p -> p.getAge() > 18 && p.getGender().equalsIgnoreCase("F");
    }

我正在为员工应用多个过滤器。

public static void main(String[] args) {

        Employee e2 = new Employee(2, 13, "F", "Martina", "Hengis");
        Employee e5 = new Employee(5, 19, "F", "Cristine", "Maria");
        Employee e7 = new Employee(7, 68, "F", "Melissa", "Roy");
        Employee e9 = new Employee(9, 15, "F", "Neetu", "Singh");


        Employee e1 = new Employee(1, 23, "M", "Rick", "Beethovan");
        Employee e3 = new Employee(3, 43, "M", "Ricky", "Martin");
        Employee e4 = new Employee(4, 26, "M", "Jon", "Lowman");
        Employee e6 = new Employee(6, 15, "M", "David", "Feezor");
        Employee e8 = new Employee(8, 79, "M", "Alex", "Gussin");
        Employee e10 = new Employee(10, 45, "M", "Naveen", "Jain");


        List<Employee> employees = new ArrayList<Employee>();
        employees.addAll(Arrays.asList(new Employee[]{e1, e2, e3, e4, e5, e6, e7, e8, e9, e10}));


        List<Predicate<Employee>> predicates = new ArrayList<>();

        predicates.add(EmployeePredicates.isAdultFemale());
        predicates.add(EmployeePredicates.firstNameLike("J"));


        final Predicate<Employee> employeePredicate = predicates.stream().reduce(Predicate::or).get();


        final List<Employee> collect = employees.stream().filter(employeePredicate).collect(Collectors.toList());

这一切都工作得很好，但是我想要做的是，对于每个应用了过滤器的员工，并打印出。让我们说

employee1被过滤掉了，因为它不是女性，等等，这有可能吗？

Answer 1

可以将调试打印添加到谓词中：

public static Predicate<Employee> firstNameLike(final String name) {
    return p -> {
        boolean passed = p.getFirstName().contains(name);
        if (!passed) {
            System.out.println(p.getFirstName() + " doesn't contain " + name);
        }
        return passed;
    }
}


public static Predicate<Employee> isAdultFemale() {
    return p -> {
        booolean passed = p.getAge() > 18 && p.getGender().equalsIgnoreCase("F");
        if (!passed) {
            System.out.println("employee not an adult female");
        }
        return passed;
    }
}