Java 8 学习笔记

整理 Java 8 的新特性。

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lambda 匿名函数
函数式接口 Java 8 : 函数式接口注解 FunctionalInterface Java 8 : 函数式接口 Runnable : 无参数, 无返回值 Java 8 : 函数式接口 Callable : 无参数, 有返回值 Java 8 : 函数式接口 Supplier : 无参数, 有返回值 Java 8 : 函数式接口 Consumer : 1个参数, 无返回值 Java 8 : 函数式接口 Function : 1个参数, 有返回值 Java 8 : 函数式接口 BiFunction : 2个参数, 有返回值
函数引用 Java 8 : 函数引用

Java 8 : 函数式接口 BiFunction : 2个参数, 有返回值


本文关键词:Java 8, 函数式接口,lambda,BiFunction。

介绍

全路径: java.util.function.BiFunction 。

Java 8 中引入。

源码:

package java.util.function;

import java.util.Objects;

/**
 * Represents a function that accepts two arguments and produces a result.
 * This is the two-arity specialization of {@link Function}.
 *
 * <p>This is a <a href="package-summary.html">functional interface</a>
 * whose functional method is {@link #apply(Object, Object)}.
 *
 * @param <T> the type of the first argument to the function
 * @param <U> the type of the second argument to the function
 * @param <R> the type of the result of the function
 *
 * @see Function
 * @since 1.8
 */
@FunctionalInterface
public interface BiFunction<T, U, R> {

    /**
     * Applies this function to the given arguments.
     *
     * @param t the first function argument
     * @param u the second function argument
     * @return the function result
     */
    R apply(T t, U u);

    /**
     * Returns a composed function that first applies this function to
     * its input, and then applies the {@code after} function to the result.
     * If evaluation of either function throws an exception, it is relayed to
     * the caller of the composed function.
     *
     * @param <V> the type of output of the {@code after} function, and of the
     *           composed function
     * @param after the function to apply after this function is applied
     * @return a composed function that first applies this function and then
     * applies the {@code after} function
     * @throws NullPointerException if after is null
     */
    default <V> BiFunction<T, U, V> andThen(Function<? super R, ? extends V> after) {
        Objects.requireNonNull(after);
        return (T t, U u) -> after.apply(apply(t, u));
    }
}

示例

代码示例1

import java.util.function.BiFunction;

public class Main {

    public static void main(String[] args) {
        BiFunction<Long, Long, Long> add = (num1, num2) -> {
            return num1 + num2;
        };

        Long result = add.apply(1L, 2L);
        System.out.println("执行结果: " + result);
    }

}

执行结果:

执行结果: 3

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