Java Programming/Arrays
< Java Programming​(Redirected from Introduction to Programming in Java/Arrays)
About Arrays
An array is a group of variables of the same data type and referred to by a common name. An array is contiguous block of memory locations referred by a common name.
i.e. To store 500 integer values in the variable multipleInt , you type this.
int[] multipleInt = new int[500]; //You just created a variable multipleInt[]. //But right now it only contains 500 0s.
Types of Arrays
One-dimensional arrays
One-dimensional array is a list of variables of the same data type.
Syntax to declare a one dimensional array
//To create an one-dimensional array, you type thistype arrayName [] = new type[length];// type is like int, char, double, etc.// ; length is how many of that type you will store

You can also declare and initialize arrays in the same statement.
For e.g.
String designations[] = {"General Manager", "Managing Director"};
Things you can do with arrays
You can print out all the values in the array. For e.g.
int[] anArray = new int[10]; // creates a new integer array with a length of 10 for(int fillUp= 0; fillUp​<​anArray​.​length​-​1​;​fillUp​++​) // This will fill the array //with numbers anArray[fillUp] = (​int​)(​Math​.​random​()​*​20 +1);// fills each spot in the //array with random numbers from 1 to 20 for(int fillUp= 0; fillUp​<​anArray​.​length​-​1​;​fillUp​++​)​// a '''for loop''' System​.​out​.​println​(​anArray​[​fillUp​]​);​// prints out the array
A possible output of the above will be:
20
2
4
13
6
18
12
14
10
Notice this part of the code
for(int fillUp= 0; fillUp​<​anArray​.​length​-​1​;​fillUp​++​)
Notice that in this part of that code:
fillUp​<​anArray​.​length​-​1
, the variable fillUp must be one less the length of the array. Why do we have to do this? You may ask. Remember, the index 0 is the first value in an array/String. So if the length was 11, and the program searched for the 12th value, it would not find it, and there would be an error that says something like this: Index Out of Range .
Two-dimensional arrays
To declare two-dimensional arrays, you need to specify multiple square brackets after the array name.
Syntax to declare a two dimensional array
type array_name = new type[rows][cols];
Advantages
/* 1. You can refer to a large number of elements by just specifying the index number and the name of the array. 2. These make it easy to do calculations in a loop.*/
Other Types of Arrays
You can also declare arrays like
int[][][] arrayexample = new int[2][2][2]; int[][][][] example2 = new int[2][2][2][2];
but it will make programming with these arrays very complicated.
The 1 dimensional array and the 2 dimensional arrays are the most commonly used

Project: Introduction to Programming in Java
Previous: Introduction to Programming in Java/Inheritance — Java Programming/Arrays — Next: Introduction to Programming in Java/Swing
Last edited on 24 September 2020, at 02:27
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