primitive

Difference between string primitive and string wrapper object in Javascript [duplicate]

由 ♀尐吖头ヾ 提交于 2019-12-08 09:12:30
问题 This question already has answers here : What's the point of new String(“x”) in JavaScript? (8 answers) Closed 4 years ago . I'm very confused about what the wrapper objects for primitives. For example, a string primitive and a string created with the string wrapper object. var a = "aaaa"; var b = new String("bbbb"); console.log(a.toUpperCase()); // AAAA console.log(b.toUpperCase()); // BBBB console.log(typeof a); // string console.log(typeof b); // object Both give access to String.prototype

Primitives Types in Java

由 一曲冷凌霜 提交于 2019-12-08 07:51:14
问题 Why to use primitive types in java instead of Wrapper classes? I want to know that already we have wrapper classes in java, then why we need to use primitive types? What are the importance of primitive types in java? 回答1: Your question is backwards. The primitive types are more fundamental than their wrappers. Really the only useful thing that wrappers give you is the ability to be treated as a subclass of Object (so that they can be put into collections and so on). All the really useful

Javascript string stored on stack

由 早过忘川 提交于 2019-12-07 09:31:00
问题 I'm reading Professional JavaScript for Web Developers 3rd ed. and in the summary of chapter 4 one can read: Two types of values can be stored in JavaScript variables: primitive values and reference values. Primitive values have one of the five primitive data types: Undefined, Null, Boolean, Number, and String. Primitive and reference values have the following characteristics: Primitive values are of a fixed size and so are stored in memory on the stack. But I can have different strings, say:

JavaFX: Storing null in a SimpleIntegerProperty

由 生来就可爱ヽ(ⅴ＜●) 提交于 2019-12-07 08:20:42
问题 I have a SimpleIntegerProperty which should be able to store null . However, this is not possible, as written in the JavaDoc of IntegerProperty: Note: setting or binding this property to a null value will set the property to "0.0". See setValue(java.lang.Number) . This also applies to other properties, such as LongProperty , FloatProperty , DoubleProperty , and BooleanProperty (but not to StringProperty , which allows null !). Why is this the case? Is there a workaround to store null in these

Java Memory usage - primitives [duplicate]

由 白昼怎懂夜的黑 提交于 2019-12-07 05:52:20
问题 This question already has answers here : How many integers can I create in 1GB memory? (2 answers) Closed 3 years ago . Quoting the following from Algorithms 4th edition "For example, if you have 1GB of memory on your computer (1 billion bytes), you cannot fit more than about 32 million int values or 16 million double values in memory at one time." int - 4 bytes 32 million x 4 = 128 million bytes Help me understand, why we can't fit 32 million int values, the above 128 million bytes is about

Custom byte size?

由 旧街凉风 提交于 2019-12-07 03:48:09
问题 So, you know how the primitive of type char has the size of 1 byte? How would I make a primitive with a custom size? So like instead of an in int with the size of 4 bytes I make one with size of lets say 16. Is there a way to do this? Is there a way around it? 回答1: Normally you'd just make a struct that represents the data in which you're interested. If it's 16 bytes of data, either it's an aggregate of a number of smaller types or you're working on a processor that has a native 16-byte

VisualVM OQL: how to search for primitive float values rather than actual Float instances?

由 爱⌒轻易说出口 提交于 2019-12-06 12:04:23
I am wondering how one can search for all primitive float values that match a certain number. When doing something like: select n from java.lang.Float n where n.value == 1.00 Only the Float class instances are being found. The application I am exploring is using different wrappers than just Float (eg. Vectors) that use primitive float values as fields for which I need to search. How would I accomplish this? The following returns a "float is not found error": select n from float n where n.value == 1.00 A primitive value exists only as a field in the structure it's a part of (or directly on the

XNA - Drawing Quads (and primitives) in right order

由 ﹥＞﹥吖頭↗ 提交于 2019-12-06 11:04:03
问题 I'm fairly new to 3D-stuff in XNA and unfortunately I have encountered a problem I can't find the solution for. (Don't even know what the problem is). To cut it short: I am drawing quads in my game using: effect.World = Matrix.Identity * Matrix.CreateRotationX(Rotation.X) * Matrix.CreateRotationY(Rotation.Y) * Matrix.CreateRotationZ(Rotation.Z) * Matrix.CreateTranslation(Position); // Apply camera-matrixes effect.View = viewMatrix; effect.Projection = projectionMatrix; graphics

== operator for primitive data types [duplicate]

由 余生长醉 提交于 2019-12-06 08:12:28
问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: How Does the toString(), ==, equals() object methods work differently or similarly on reference and primitive types? I am trying to understand the difference between == and equals to operator in Java. e.g. == will check if it is the same object while equals will compare the value of the object ... Then why do we use == for comparing primitive data types like int. Because if I have int i =7; //and int j = 6. They

Is there a reason to always use Objects instead of primitives?

由 走远了吗. 提交于 2019-12-06 04:19:41
问题 So I just started my second programming class in Java, and this is the example given to us by the professor to demonstrate loops and arrays. public class ArraysLoopsModulus { public static void main(String [ ] commandlineArguments){ //Declare & Instatiate an Array of 10 integers Integer[ ] arrayOf10Integers = new Integer[10]; //initialize the array to the powers of 2 Integer powersOf2 = new Integer(1); for(int i=0;i<arrayOf10Integers.length;i++){ arrayOf10Integers[i] = powersOf2; //multiply
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