为什么Java 8引入* Integer.sum（int a，int b）* [英] Why did Java 8 introduce *Integer.sum(int a, int b)*

问题描述

我刚注意到JDK8为 Integer 类引入了此方法：

I just noticed that JDK8 introduced this method for Integer class:

 /**
 * Adds two integers together as per the + operator.
 *
 * @param a the first operand
 * @param b the second operand
 * @return the sum of {@code a} and {@code b}
 * @see java.util.function.BinaryOperator
 * @since 1.8
 */
public static int sum(int a, int b) {
    return a + b;
}

这种方法有什么意义？为什么我应该调用此方法而不是使用 + 运算符？我能想到的唯一可能性是，例如，当混合字符串和整数时， + 运算符会改变含义，所以

What's the point of this method? Why should i call this method instead of using the + operator? The only possibility I can think of is that, for instance, when mixing strings and ints the + operator changes meaning, so

System.out.println("1"+2+3); // prints 123
System.out.println("1"+Integer.sum(2,3)); // prints 15

但是使用括号仍可以使用

but using parenthesis would work anyway

System.out.println("1"+(2+3)); // prints 15

推荐答案

它可以作为一种方法很有用传递给需要相关功能接口的方法（ IntBinaryOperator ）。

It can be useful as a method reference (Integer::sum) passed to a method that requires a relevant functional interface (IntBinaryOperator).

例如：

int sum = IntStream.range(1,500).reduce(0,Integer::sum);

当然，这个例子可以使用 .sum（）而不是减少。我刚注意到的Javadoc IntStream.sum 提到这个精确的减少等同于sum（）。

Of course, this example can use .sum() instead of reduce. I just noticed that the Javadoc for IntStream.sum mention this exact reduction as being equivalent to sum().

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