Cast primitive type array into object array in java
Here is a simple one-liner: Double[] objects = ArrayUtils.toObject(primitives); You will need to import Apache commons-lang3: import org.apache.commons.lang3.ArrayUtils;
primitive
Using int vs Integer
the Integer class is provided so that values can be boxed/unboxed in a pure OO manner. use int where appropriate unless you specifically need to use it in an OO way; in which case Integer is appropriate. Java Int vs Integer However, very different things are going on under the covers here. An int is … Read more
Increment variable names? [duplicate]
You can’t do this in Java and more importantly, you don’t want to do this as this isn’t how Java works. In fact variable names aren’t nearly as important as you think and hardly even exist in compiled code. What is much more important is that you are able to get a reference to your … Read more
Is an int a 64-bit integer in 64-bit C#?
No. The C# specification rigidly defines that int is an alias for System.Int32 with exactly 32 bits. Changing this would be a major breaking change.
Are primitive datatypes thread-safe in Java
There are three ways in which they’re not safe: long and double aren’t even guaranteed to be updated atomically (you could see half of a write from a different thread) The memory model doesn’t guarantee that you’ll see the latest updates from one thread in another thread, without extra memory barriers of some kind The … Read more
Why doesn’t Kotlin allow to use lateinit with primitive types?
For (non-nullable) object types, Kotlin uses the null value to mark that a lateinit property has not been initialized and to throw the appropriate exception when the property is accessed. For primitive types, there is no such value, so there is no way to mark a property as non-initialized and to provide the diagnostics that … Read more
Java Arrays.asList on primitive array type produces unexpected List type [duplicate]
The problem is that Arrays.asList takes a parameter of T… array. The only applicable T when you pass the int[] is int[], as arrays of primitives will not be autoboxed to arrays of the corresponding object type (in this case Integer[]). So you can do Arrays.asList(new Integer[] {1, 2, 3});.
How can you pass multiple primitive parameters to AsyncTask?
Just wrap your primitives in a simple container and pass that as a parameter to AsyncTask, like this: private static class MyTaskParams { int foo; long bar; double arple; MyTaskParams(int foo, long bar, double arple) { this.foo = foo; this.bar = bar; this.arple = arple; } } private class MyTask extends AsyncTask<MyTaskParams, Void, Void> { … Read more
How does double to int cast work in Java
It’s all documented in section 5.1.3 of the JLS. In the first step, the floating-point number is converted either to a long, if T is long, or to an int, if T is byte, short, char, or int, as follows: If the floating-point number is NaN (ยง4.2.3), the result of the first step of the … Read more
Java: Why am I required to initialize a primitive local variable?
Because it’s a local variable. This is why nothing is assigned to it : Local variables are slightly different; the compiler never assigns a default value to an uninitialized local variable. If you cannot initialize your local variable where it is declared, make sure to assign it a value before you attempt to use it. … Read more