如何从int到字节投，然后用bitshift运营商 [英] How to cast from int to byte, then use a bitshift operator

问题描述

为什么下面不工作？我投一个int到字节，那么在位由7转向我看不出有任何问题出现。

不过，我得到错误信息precision ...需要的可能的损失：字节;实测值：INT

像素是一个字节数组， C 是一个Color对象， ITER 是一个整数。

 像素[ITER ++] =（（字节）c.getRed（））＆LT;＆LT; 7;
像素[ITER ++] =（（字节）c.getGreen（））≤;＆下; 7;
像素[ITER ++] =（（字节）c.getBlue（））≤;＆下; 7;
 

解决方案

在Java中，移位运算符返回 INT 价值，即使被转移的数量是字节。你需要用中投为字节围绕整个前pression：

 像素[ITER ++] =（字节）（c.getRed（）＆LT;＆LT; 7）;
像素[ITER ++] =（字节）（c.getGreen（）＆所述; 7;）;
像素[ITER ++] =（字节）（c.getBlue（）＆所述; 7;）;
 

Why does the following not work? I cast an int to a byte, then shift the bits over by 7. I don't see any problems there.

However, I get the error message "possible loss of precision... required: byte; found: int"

pixels is an array of bytes, c is a Color object, iter is an integer.

pixels[iter++] = ((byte) c.getRed()) << 7;
pixels[iter++] = ((byte) c.getGreen()) << 7;
pixels[iter++] = ((byte) c.getBlue()) << 7;

解决方案

In Java, the shift operators return an int value, even if the quantity being shifted is a byte. You need to wrap the cast to byte around the entire expression:

pixels[iter++] = (byte) (c.getRed() << 7);
pixels[iter++] = (byte) (c.getGreen() << 7);
pixels[iter++] = (byte) (c.getBlue() << 7);

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