将方法保存到变量java 8中 [英] Save a method into a variable, java 8

问题描述

是否可以将方法保存到变量中？

我有一个名为MyFilter的类，它在不同的字段上过滤项目。

MyFilter的构造函数应该询问2件事：

Is it possible to save a method into a variable?
I have a class which is called MyFilter and it filters Items on different fields.
The constructor of MyFilter should ask 2 things:

1. 字符串，例如按语言过滤项目，英语


2. 这应该是一种方法

例如：

我有一个项目和我想检查语言==字符串是否给过滤器

所以我需要得到该项的语言，所以Item.getLanguage（）...

我还需要它适用于Item.getTitle（），Item.getId（）等。

I have an Item and I want to check if the language == String given to the filter
So I need to get the language of that Item, so Item.getLanguage()...
I also need it for Item.getTitle(), Item.getId() and so on.

我认为这可能与lambda有关，但我不知道如何。

I think this is possible with lambda's but I don't know how.

推荐答案

是的，您可以对任何方法进行变量引用。对于简单的方法，通常使用 java.util.function。类就足够了。对于复杂方法，您必须使用此方法定义 @FunctionalInterface 。以下是工作示例：

Yes, you can have a variable reference to any method. For simple methods it's usually enough to use java.util.function. classes. For complex methods you have to define your @FunctionalInterface with this method. Here's working example:

import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;

public class Main {

    public static void main(String[] args) {
        final Consumer<Integer> simpleReference = Main::someMethod;
        simpleReference.accept(1);
        simpleReference.accept(2);
        simpleReference.accept(3);

        final ComplexInterface complexReference = Main::complexMethod;
        final String complexResult = complexReference.someMethod("888", 321, new ArrayList<>());
        System.out.println(complexResult);
    }

    private static void someMethod(int value) {
        System.out.println(value);
    }

    private static String complexMethod(String stringValue, int intValue, List<Long> longList) {
        final StringBuilder builder = new StringBuilder();
        builder.append(stringValue).append(" : ").append(intValue);
        for (Long longValue : longList) {
            builder.append(longValue);
        }
        return builder.toString();
    }

    @FunctionalInterface
    public static interface ComplexInterface{
        String someMethod(String stringValue, int intValue, List<Long> longList);
    }
}

这篇关于将方法保存到变量java 8中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！