dalvik

问题 The default floating point type in Java is the double. If you hard code a constant like 2.5 into your program, Java makes it a double automatically. When you do an operation on floats or ints that could potentially benefit from more precision, the type is 'promoted' to a double. But in the Android API, everything seems to be a float from sound volumes to rectangle coordinates. There's a structure called RectF used in most drawing; the F is for float. It's really a pain for programmers who are

问题 The default floating point type in Java is the double. If you hard code a constant like 2.5 into your program, Java makes it a double automatically. When you do an operation on floats or ints that could potentially benefit from more precision, the type is 'promoted' to a double. But in the Android API, everything seems to be a float from sound volumes to rectangle coordinates. There's a structure called RectF used in most drawing; the F is for float. It's really a pain for programmers who are

问题 Google added a new ART runtime with Android 4.4. How can I determine whether ART or Dalvik is the current runtime? 回答1: Update At least, as early as June 2014 Google has released an official documentation on how to correctly verify the current runtime in use: You can verify which runtime is in use by calling System.getProperty("java.vm.version"). If ART is in use, the property's value is "2.0.0" or higher. With that, now there is no need to go through reflection and simply check the

问题 I am getting following Exception on Android 2.2.1: java.lang.NoSuchMethodError: java.lang.String.isEmpty I am calling text.isEmpty from Scala. Any idea, how to solve this? 回答1: Use JRE/JDK 1.5, which did not have an isEmpty method on String . This will avoid situations where Scala uses 1.6's isEmpty instead of its own. If you have Java libraries as well, be sure to pick ones compatible with 1.5. 回答2: java.lang.String.isEmpty() was added in Gingerbread (2.3). You will have to write your own

问题 I am getting following Exception on Android 2.2.1: java.lang.NoSuchMethodError: java.lang.String.isEmpty I am calling text.isEmpty from Scala. Any idea, how to solve this? 回答1: Use JRE/JDK 1.5, which did not have an isEmpty method on String . This will avoid situations where Scala uses 1.6's isEmpty instead of its own. If you have Java libraries as well, be sure to pick ones compatible with 1.5. 回答2: java.lang.String.isEmpty() was added in Gingerbread (2.3). You will have to write your own

问题 I am getting following Exception on Android 2.2.1: java.lang.NoSuchMethodError: java.lang.String.isEmpty I am calling text.isEmpty from Scala. Any idea, how to solve this? 回答1: Use JRE/JDK 1.5, which did not have an isEmpty method on String . This will avoid situations where Scala uses 1.6's isEmpty instead of its own. If you have Java libraries as well, be sure to pick ones compatible with 1.5. 回答2: java.lang.String.isEmpty() was added in Gingerbread (2.3). You will have to write your own

问题 I'm having an issue where the dalvik.system.PathClassLoader can't find my jni file on Intel devices. I think it has to do with the structure of an aar dependency I have because once I removed that dependency, the jni file is found without issue. My aar dependency has x86 and arm libraries and my project only has arm libraries. The folder structure is: My Project src jniLibs armeabi libLibraryA.so My AAR dependency Project has: src jniLibs armeabi libLibraryB.so x86 libLibraryB.so With that

问题 I am tracing the Dalvik machine source code. According that, I want to make Dalvik runnable. I have seem the dvk project. But there has many problem result in fault. Are there have any way to make dalvik only without all android. Because make android will take too much time (about many hour) dvk project: http://code.google.com/p/dvk/ 回答1: if you build the lunch "sim-eng", you get a dalvikvm built for just the host (i.e. the Linux box you're building on). this already runs with glibc rather

问题 I have code like this : int a = 629339; int b = 4096; long res = a*b; The result is -1717194752 but if I add one manual cast to long long res = ((long)a)*b; or long res = (long) a*b; the result is correct 2577772544 Who can explain how does it works. 回答1: long res = a*b; a*b will be treated as integer unless you add 'l' at end (or) cast. As per java tutorial The int data type is a 32-bit signed two's complement integer. It has a minimum value of -2,147,483,648 and a maximum value of 2,147,483

问题 I have code like this : int a = 629339; int b = 4096; long res = a*b; The result is -1717194752 but if I add one manual cast to long long res = ((long)a)*b; or long res = (long) a*b; the result is correct 2577772544 Who can explain how does it works. 回答1: long res = a*b; a*b will be treated as integer unless you add 'l' at end (or) cast. As per java tutorial The int data type is a 32-bit signed two's complement integer. It has a minimum value of -2,147,483,648 and a maximum value of 2,147,483