CODEWITHSUNDEEP
javaandroidflagsbit
strok_777
strok_777

Reputation: 1341

check all the values of flag bits java Android

I've read this post in order to check the flags for ApplicationInfo . But then I read this post in order to see if there's a way to get all the values contained in a flag, but I'm a bit confused. Can anyone tell me if there's a way to get all the values and explain it?

Thanks in advance.

Upvotes: 2

Views: 1973

Answers (1)

lelloman
lelloman

Reputation: 14183

int flags work this way, you have an integer, say 48, in binary it would be 0011 0000. this means it contains 2 flags one is 0010 0000 and the other one is 0001 0000. if you check ApplicationInfo flags you would notice that all the values are powers of 2 (1,2,4,8..) this is because the binary representation of a power of 2 is all zeros and only one 1. so, in order to check what flags the integer 48 contains, you can do it this way (notice the & operator, it's a bitwise AND, if you have doubts about it please read this):

int value = 48;
int[] possibleFlags = {ApplicationInfo.FLAG_FACTORY_TEST, ApplicationInfo.FLAG_ALLOW_TASK_REPARENTING, ApplicationInfo.FLAG_ALLOW_BACKUP};
String[] flagNames = {"FLAG_FACTORY_TEST", "FLAG_ALLOW_TASK_REPARENTING", "FLAG_ALLOW_BACKUP"};

 for (int i = 0; i < possibleFlags.length; i++) {
    int aFlag = possibleFlags[i];
    String name = flagNames[i];
    boolean hasFlag = (value & aFlag) > 0;
    Log.d("Flags", String.format("flag %s %s", name, hasFlag ? "PRESENT" : "NOT PRESENT"));
}

I didn't really understand the approach you're asking about, but another way to check all the flags is to iterate all powers of 2 from 1 to 31 (for 4 bytes integers like java) but you still need to link the numbers to the actual constant, would it be useful? e.g.

for (int i = 0; i < 32; i++) {
    int aFlag = 1 << i;
    boolean hasFlag = (value & aFlag) > 0;
    Log.d("Flags", String.format("flag %s %s", aFlag, hasFlag ? "PRESENT" : "NOT PRESENT"));
}

Upvotes: 3

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