在Java流中拆分对象

我想知道是否可以在流内拆分对象.例如,对于此员工：

public class Employee {

    String name;
    int age;
    double salary;

    public Employee(String name, int age, double salary) {
        this.name = name;
        this.age = age;
        this.salary = salary;
    }

    public String getName() { return name; }

    public int getAge() { return age; }

    public double getSalary() { return salary; }
}

我想在流中执行一些操作.为简单起见,让它像这样(假设我的代码架构不允许将它放在Employee类中 – 否则它会太容易了)：

public void someOperationWithEmployee(String name, int age, double salary) {
    System.out.format("%s %d %.0f\n", name, age, salary);
}

现在它看起来像这样：

Stream.of(new Employee("Adam", 38, 3000), new Employee("John", 19, 2000))
        // some conversations go here ...
        .forEach(e -> someOperationWithEmployee(e.getName, e.getAge(), e.getSalary));

问题是 – 是否可以将一些代码放在流中？

Stream.of(new Employee("Adam", 38, 3000), new Employee("John", 19, 2000))
        // some conversations go here
        .forEach((a, b, c) -> someOperationWithEmployee(a, b, c));

我想要实现的目标是什么？ – 我想如果我可以映射一些对象字段然后处理像.forEach(this :: someOperationWithEmployee)那样的代码可读性会略有提高.

2015年5月14日更新

毫无疑问,将Employee对象传递给someOperationWithEmployee在这种情况下是最漂亮的解决方案,但有时我们不能在现实生活中做到这一点,并且应该是lambdas的通用解决方案.

解决方法:

我不确定这是否适合您的需求,但它有点反复,而不是检查某些类型.

您可以这样运行我的解决方案：

    Stream.of(new Employee("Adam", 38, 3000), new Employee("John", 19, 2000))
        .forEach(
                e->ArrayCaller.<TriConsumer<String, Integer, Double>>convert(e::getName, e::getAge, e::getSalary)
                                                                     .call((a, b, c) -> operation(a, b, c)));

它会称这个’main’类的简单方法：

private void operation(String name, int age, double salary) {
    System.out.format("%s %d %.0f\n", name, age, salary);
}

当然它需要这种辅助类型：

/** Extending interfaces must have a method called consume with N args */
interface NConsumer {}

/*
 * Method must be called consume for reflection.
 *
 * You can define N interfaces like this.
 */
nterface TriConsumer<A, B, C> extends NConsumer {
    void consume(A a, B b, C c);
}

interface ArrayCaller<E extends NConsumer> {
    void call(E code);
    static <T extends NConsumer> ArrayCaller<T> convert(Supplier<?>...argSuppliers) {
        final Object[] args = new Object[argSuppliers.length];
        for (int i = 0; i < argSuppliers.length; i++) {
            args[i] = argSuppliers[i].get();
        }
        return new ArrayCaller<T>() {
            @Override
            public void call(T code) {
                for (Method m: code.getClass().getMethods()) {
                    if (m.getName().equals("consume")) {
                        try {
                            m.invoke(code, args);
                        } catch (IllegalAccessException
                                | IllegalArgumentException
                                | InvocationTargetException e) {
                            throw new RuntimeException(e);
                        }
                    }
                }
            }
        };
    }
}

标签：java,java-8,java-stream,method-reference
来源： https://codeday.me/bug/20190612/1222699.html