Arrays in Java.
Arrays in Java.
Content :-
1.Java Arrays.
2.Java Arrays Loop.
3.Java Multi-Dimensional Arrays.
1.Java Arrays,
Instead of defining distinct variables for each item, arrays are used to hold numerous values in a single variable.
To declare an array, use square brackets to define the variable type :-
String[] cars;
We've now declared a variable that holds a string array. We can use an array literal to add values to it by placing the items in a comma-separated list inside curly braces :-
String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
You may write: to make an array of integers,
int[] myNum = {10, 20, 30, 40};
1.1.Access the Elements of an Array,
The index number is used to access an array element.
In automobiles, this statement gets the value of the first element :-
Example :-
String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
System.out.println(cars[0]);
// Outputs Volvo
Note that array indexes begin at 0: The first element is [0]. The second element is [1], and so on.
1.2.Change an Array Element,
Refer to the index number to change the value of a certain element :-
Example :-
cars[0] = "Opel";
Example :-
String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
cars[0] = "Opel";
System.out.println(cars[0]);
// Now outputs Opel instead of Volvo
1.3.Array Length,
Use the length property to determine the number of elements in an array :-
Example :-
String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
System.out.println(cars.length);
// Outputs 4
2.Java Arrays Loop,
2.1.Loop Through an Array,
The for loop can be used to loop through the array elements, and the length property can be used to determine how many times the loop should execute.
All elements in the automobiles array are output in the following example :-
Example :-
String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
for (int i = 0; i < cars.length; i++) {
System.out.println(cars[i]);
}
2.2.Loop Through an Array with For-Each,
A "for-each" loop is also available, which is used to loop through elements in arrays :-
Syntax :-
for (type variable : arrayname) {
...
}
Using a "for-each" loop, the following example prints every element in the vehicles array :-
Example :-
String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
for (String i : cars) {
System.out.println(i);
}
The preceding example might be understood as follows: print the value of I for each String element (called I - as in index) in vehicles.
When comparing the for and for-each loops, you'll notice that the for-each technique is easier to code, requires no counter (since it uses the length property), and is more readable.
3.Java Multi-Dimensional Arrays,
3.1.Multidimensional Arrays,
An array of arrays is a multidimensional array.
Add each array within its own set of curly brackets to make a two-dimensional array :-
Example :-
int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };
myNumbers is now an array that contains two arrays as items.
To get to the items in the myNumbers array, you'll need two indexes: one for the array and one for each element within it. This example uses the third member (2) of myNumbers' second array (1) :-
Example :-
int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };
int x = myNumbers[1][2];
System.out.println(x); // Outputs 7
To acquire the items of a two-dimensional array, we can use a for loop inside another for loop (we still need to point to the two indexes) :-
Example :-
public class Main {
public static void main(String[] args) {
int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };
for (int i = 0; i < myNumbers.length; ++i) {
for(int j = 0; j < myNumbers[i].length; ++j) {
System.out.println(myNumbers[i][j]);
}
}
}
}
Reference :- w3schools.com
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