检查标志位的java [英] Checking flag bits java

问题描述

我有标志位的问题。
我有一个int变量保存标志。首先，我设置一些标志变量。后来，我需要检查有多少个旗变量分别设置。但我不知道这样做。
请帮帮我。
谢谢，
Nagaraju。

I have a problem with flag bits. I have an int variable to hold flags. first i set some flags to that variable. later i need check how many flags were set in that variable. But i don't know to do it. please help me. Thank you, Nagaraju.

推荐答案

要检查，看是否有位值设置：

To check to see if a bit value is set:

int value = VALUE_TO_CHECK | OTHER_VALUE_TO_CHECK;

if ((value & VALUE_TO_CHECK) == VALUE_TO_CHECK)
{
    // do something--it was set
}

if ((value & OTHER_VALUE_TO_CHECK) == OTHER_VALUE_TO_CHECK)
{
    // also set (if it gets in here, then it was defined in 
    //   value, but it does not guarantee that it was set with
    //   OR without other values. To guarantee it's only this
    //   value just use == without bitwise logic)
}

要注意，你不应该有一个检查值0，除非它再presents全部或无（不要使用按位逻辑来比较是很重要的;只需使用价值== 0 ），因为任何价值和放大器; 0 始终为0。

It's important to note that you should not have a checked value as 0 unless it represents All or None (and don't use bitwise logic to compare; just use value == 0) because any value & 0 is ALWAYS 0.

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