Java array initialization second variable type

java initialize array with values
initialize array java
java array of objects
one dimensional array in java
array length java
double array java
dynamic array in java
how to declare string array in java
int[] myArray = new int[5];

Hey guys, I know there are other ways to initialize an array like:

int[] myArray = {1,2,3,4,5};

But can you tell me what the second int in the top example stands for? I think the first "int" already specifies the array to have integer values, doesn't it?

With int and other primitive types, you're correct, the double declaration is largely superfluous.

But consider this example:

Object [] array = new String[5];

This is valid Java code (even though it is slightly broken*).

On a more general level it follows the same pattern as when you're initialising any variable with a new object:

Foo foo = new Foo();

The first Foo is the type of the variable (what shape the box is), the second is the type of the actual object (what shape is the thing you put in the box).

Note: Starting with Java 10, you can declare local variables with the keyword var, thus eliminating the need to specify the type twice:

var array = new int[5];

The compiler will infer from this that the type of array will be the same as the object it's initialised with. (int[] in this case).

*It is broken because if you try to put into the array anything other than a String, the code only fails at runtime, not during compilation.

Arrays in Java, Like array of int type, we can also create an array of other primitive data types like char, float, double..etc or user initialize the second elements of the array. Array Initialization An array in Java is a type of object that can contain a number of variables. These variables can be referenced only by the array index—a nonnegative integer.

The construct in int[] myArray = { 1, 2, 3, 4, 5 }; is handled as a special case. The compiler knows that { 1, 2, 3, 4, 5 } is creating an int[] array because of the declared type.

However, the full array creation syntax for the int array is new int[5] (it can vary), which tells the compiler that a new int[] array is created, regardless of the declared type:

For example, you can declare an Object variable, and assign an int array to it:

Object myArrayObject = new int[5]; //OK: this creates an int array

Whereas this won't work:

Object myArrayObject = { 1, 2, 3, 4, 5 }; //won't compile

Chapter 10. Arrays, In the Java programming language, arrays are objects (§4.3.1), are of an array component of type double is always an element of the double value set. Declaring a variable of array type does not create an array object or allocate any An array initializer creates an array and provides initial values for all its components. Today we will learn how to initialize an array in java. An array in java is a container that can hold a fixed number of values of the same type. The values can be of the primitive type like int, short, byte or it can be an object like String, Integer etc. Table of Contents.

So when you type new, you are specifying you want java to allocate memory to the heap. How much memory? Ah yes enough memory for 5 integers, int[5]. So java will allocated enough consecutive memory on the heap to store 5 integers.

Arrays (The Java™ Tutorials > Learning the Java Language , The Java Tutorials have been written for JDK 8. new int[10]; // initialize first element anArray[0] = 100; // initialize second element anArray[1] = 200; Like declarations for variables of other types, an array declaration has two components: the  For example data of Integer or Strings etc. Java Array is fixed number of Homogeneous (same kind) data with indexing of every element. This is very useful data type in java. This J ava array tutorial you will learn about what is Array in Java, some useful methods, how to Initialization and types with relevant examples.

int[] myArray = new int[5];

means you declare an array that can contain integer values called myArray (by int[] myArray) and you define it as an integer-array of size 5 afterwards (= new int[5];);

These steps are made inline, you could alternatively do the same in two lines:

int[] myArray;        // declaration
myArray = new int[5]; // definition

Creating and Using Arrays, Like declarations for variables of other types, an array declaration has two components: the array's You create an array explicitly using Java's new operator. The java.util.Arrays class has several methods named fill() which accept different types of arguments and fill the whole array with the same value: long array[] = new long[5]; Arrays.fill(array, 30); The method also has several alternatives which set a range of an array to a particular value: int array[] = new int[5]; Arrays.fill(array, 0, 3, -50);

First is the data type of the array. And other int is for the intialization of 5 integer object in the array

Initializing arrays in Java, Learn how to initialize arrays in Java. Arrays are a helpful data type for managing elements in contiguous memory location. In this case, we rely on the array initializer new double[3][3] to set the array to zeros, and then use a  In a variable declaration (§8.3, §8.4.1, §9.3, §14.14, §14.20) except for a variable arity parameter, the array type of a variable is denoted by the array type that appears at the beginning of the declaration, followed by any bracket pairs that follow the variable's Identifier in the declarator.

Declare and Initialize Arrays in Java, We can declare and initialize arrays in Java by using new operator with array. Type[] arr = new Type[] { comma separated values }; declaring an array where [] appears after the variable name, similar to C/C++ style arrays. The first line depict the array declaration and the second line represents the array initialization​. First, you must declare a variable of the desired array type. Second, you must allocate the memory that will hold the array, using new, and assign it to the array variable. Thus,  in Java all arrays are dynamically allocated. In a situation, where the size of the array and variables of array are already known, array literals can be used.

Java double Array, Complete Tutorial on Java primitive double data type array. that variable is of type array remaining variables in that declaration are not array variables those  Java Initialize Array Examples. An array is a type of variable that can hold multiple values of similar data type. This is very useful for storing values when we don't know how many of them is needed, or when the number of values is very large.

Day 5 -- Arrays, Conditionals, and Loops, Unlike in other languages, however, arrays in Java are actual objects that can be Array variables indicate the type of object the array will hold (just as they do for The second step is to create an array object and assign it to that variable. If you don't initialize an array when you declare it, the values of the initial slots will  Like declarations for variables of other types, an array declaration has two components: the array's type and the array's name. An array's type is written as type[], where type is the data type of the contained elements; the brackets are special symbols indicating that this variable holds an array. The size of the array is not part of its type (which is why the brackets are empty).

Comments
  • Yes it specifies that the values are ints but not how many values are allows
  • defines an array that has space to hold 5 int. You can find further information on this link : stackoverflow.com/questions/6222531/…
  • The first int is for declaration: this variable will be an array containing primitive int elements. The second int is for instantiation: you are allocating memory to hold the int elements.
  • The first int is part of the specification of the type of variable myArray. The second int is part of a Java expression that instantiates an array of int. That the expression produces an object of the correct type for initialization of the variable does follow from the repeat of int, but that does not imply that it is redundant.
  • @AvoKarato your proposed alternative is syntactically invalid. The new operator requires a type as its operand, and [5] is not a type. You can view the requirement for the type to be repeated as a safety mechanism, but I prefer to understand it by viewing the overall statement is a compound of two substantially independent pieces (variable declaration and initializer), each of which has its own rules. Java is requiring consistency in how you instantiate arrays.
  • And as I recall, the int[] myArray = { 1, 2, 3, 4, 5 } form wasn't always supported. I don't remember when it was introduced, but I'm pretty sure that back in the day you had to spell out int[] myArray = new int[] { 1, 2, 3, 4, 5 } (which you still can do).
  • But when int[] my Array = new any other type than int [5] wouldnt compile, why does java want me to say int AGAIN?
  • @AvoKarato It's not just about stating int. Remember, you also specify the size (new int[5] or new int[arraySize] using a variable). Would you have wanted java to allow you to type new [5] or something like that? It doesn't make much difference and the benefit of allowing developers to omit int just when initializing inline would be insignificant.