flags

Storing EnumSet in a database?

由 孤人 提交于 2019-11-26 17:10:01
问题 So in C++/C# you can create flags enums to hold multiple values, and storing a single meaningful integer in the database is, of course, trivial. In Java you have EnumSets, which appear to be quite a nice way to pass enums around in memory, but how do you output the combined EnumSet to an integer for storage? Is there another way to approach this? 回答1: // From Adamski's answer public static <E extends Enum<E>> int encode(EnumSet<E> set) { int ret = 0; for (E val : set) { ret |= 1 << val

Print All JVM Flags

由 拥有回忆 提交于 2019-11-26 15:37:39
Found an interesting JVM Flag : java -XX:+UnlockDiagnosticVMOptions -XX:+PrintFlagsFinal -version It prints hundreds of various options, I never heard about before. It also prints default values, that helps diagnose JVM behaviors better. Another interesting flag is: -XX:+UnlockExperimentalVMOptions Does anyone knows of any documentation which explains each one of them ? Before dive into sources you can skim over following extracts and find suitable option faster: https://chriswhocodes.com/ (OracleJDK 6/7/8/9/10/11/12, OpenJDK 8/9/10/11, Graal CE/EE, OpenJ9, Zing) http://jvm-options.tech.xebia

CMake cross-compiling: C flags from toolchain file ignored

由 ぃ、小莉子 提交于 2019-11-26 12:27:45
问题 I use cmake for cross compiling. In my toolchain file there is a line SET(CMAKE_C_FLAGS \"-std=gnu99\") This variable is not set in CMakeLists.txt again. When I run cmake -DCMAKE_TOOLCHAIN_FILE=toolchain.cmake .. this flag is ignored. To be more detailed: The line of flags.cmake shows an empty C_FLAGS = line. But in CMakeOutput.log I can find a line Build flags: -std=gnu99 . I found out that a second run of cmake .. (same with or without toolchain file specified) fixes this problem. But why

Activity stack ordering problem when launching application from Android app installer and from Home screen

由 倾然丶 夕夏残阳落幕 提交于 2019-11-26 11:56:11
问题 For testing purposes only, I am allowing my app APK to be downloaded and installed via a URL. Once downloaded on the phone, it can be launched with the Android app installer which gives the user an option to install it to their device and then run it. Consider if we downloaded and ran the app in the way described above. The main/launcher activity in my app is a login page ( Activity A ). Once the user is authenticated, they are taken to the main area of the application, e.g. Activity B . So

overridePendingTransition does not work when FLAG_ACTIVITY_REORDER_TO_FRONT is used

由 你。 提交于 2019-11-26 11:09:01
问题 I have two activities in the stack, in order to show them I use FLAG_ACTIVITY_REORDER_TO_FRONT. So far so good, the problem comes when I want to bring the activity with an animation using overridePendingTransition. Intent i = new Intent(ActivityA.this, ActivityB.class); i.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT); ActivityA.this.startActivity(i); overridePendingTransition(R.anim.transition_to_right, R.anim.transition_to_left); The transition is not shown, however, if the flag is not

What does the [Flags] Enum Attribute mean in C#?

由 萝らか妹 提交于 2019-11-26 08:50:33
问题 From time to time I see an enum like the following: [Flags] public enum Options { None = 0, Option1 = 1, Option2 = 2, Option3 = 4, Option4 = 8 } I don\'t understand what exactly the [Flags] -attribute does. Anyone have a good explanation or example they could post? 回答1: The [Flags] attribute should be used whenever the enumerable represents a collection of possible values, rather than a single value. Such collections are often used with bitwise operators, for example: var allowedColors =

about assembly CF(Carry) and OF(Overflow) flag

由 痴心易碎 提交于 2019-11-26 07:30:36
问题 It\'s known that CF indicates unsigned carry out and OF indicates signed overflow. So how does an assembly program differentiate between unsigned and signed data since it\'s only a sequence of bits? (Through additional memory storage for type information, or through positional information or else?) And could these two flags be used interchangeably? 回答1: The distinction is in what instructions are used to manipulate the data, not the data itself. Modern computers (since circa 1970) use a

Perl flags -pe, -pi, -p, -w, -d, -i, -t?

由 这一生的挚爱 提交于 2019-11-26 07:07:01
问题 I have seen lots of ways of running Perl code or scripts, with different flags. However, when I try to google for what each flag means, I mainly get results to generic Perl sites and no specific information regarding the flags or their use is found there. Below are the flags that I encounter most often, and I don\'t have a clue what they mean: perl -pe perl -pi perl -p perl -w perl -d perl -i perl -t I will be very grateful if you tell me what each of those mean and some use cases for them,

How to Compare Flags in C#?

由 别说谁变了你拦得住时间么 提交于 2019-11-26 06:31:12
问题 I have a flag enum below. [Flags] public enum FlagTest { None = 0x0, Flag1 = 0x1, Flag2 = 0x2, Flag3 = 0x4 } I cannot make the if statement evaluate to true. FlagTest testItem = FlagTest.Flag1 | FlagTest.Flag2; if (testItem == FlagTest.Flag1) { // Do something, // however This is never true. } How can I make this true? 回答1: In .NET 4 there is a new method Enum.HasFlag. This allows you to write: if ( testItem.HasFlag( FlagTest.Flag1 ) ) { // Do Stuff } which is much more readable, IMO. The

Print All JVM Flags

由 孤街醉人 提交于 2019-11-26 04:30:55
问题 Found an interesting JVM Flag : java -XX:+UnlockDiagnosticVMOptions -XX:+PrintFlagsFinal -version It prints hundreds of various options, I never heard about before. It also prints default values, that helps diagnose JVM behaviors better. Another interesting flag is: -XX:+UnlockExperimentalVMOptions Does anyone knows of any documentation which explains each one of them ? 回答1: Before dive into sources you can skim over following extracts and find suitable option faster: https://chriswhocodes
订阅 flags