java 推断类型不符合上限
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/27245994/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Inferred type does not conform to upper bound(s)
提问by Jeffrey Tai
I'm doing a project in which I have to negate the pixels of a PPM file (image).
我正在做一个项目，我必须否定 PPM 文件（图像）的像素。
I implemented my negate function as such:
我这样实现了我的否定函数：
public PPMImage negate()
{
RGB[] negated = new RGB[pixels.length];
System.arraycopy(pixels, 0, negated, 0, pixels.length);
RGB[] negatedArr = Arrays.stream(negated).parallel().map(rgb -> rgb.neg(maxColorVal)).toArray(size -> new RGB[size]);
return new PPMImage(width, height, maxColorVal, negatedArr);
}
With the neg(maxColorVal)function being defined as this:
与neg(maxColorVal)函数被定义为这样的：
public void neg(int maxColorVal)
{
R = maxColorVal - R;
G = maxColorVal - G;
B = maxColorVal - B;
}
When I compile the code, I get the following error:
当我编译代码时，出现以下错误：
error: incompatible types: inferred type does not conform to upper bound(s)
RGB[] negatedArr = Arrays.stream(negated).parallel().map(rgb -> rgb.neg(maxColorVal)).toArray(size -> new RGB[size]);
inferred: void
upper bound(s): Object
The error points at the map() function. What am I doing incorrectly?
错误指向 map() 函数。我做错了什么？
采纳答案by Eran
Correction :
更正：
Your mapfunction expects a method that returns some reference type, but neghas a voidreturn type.
您的map函数需要一个返回某种引用类型但neg具有void返回类型的方法。
Try to change your negmethod to :
尝试将您的neg方法更改为：
public RGB neg(int maxColorVal) {
R = maxColorVal - R;
G = maxColorVal - G;
B = maxColorVal - B;
return this;
}
