Arrays in Java

Arrays

Arrays are the collection of similar types of data. They are used to store multiple values in a single variable. To declare an array, you can define variable types with a square bracket.

Syntax

 // Array Syntax
datatype[] arrayname;

Example

 public class Main {
    public static void main(String[] args) {
            // Array Example
            String []  names = {"Anar Singh Basnet", "Rama Aryal", "Rachana", "Ram Adhikari", "Munu"};
            int [] grades = {50,60,70,80,90};
         
            System.out.println(names[1]);
            System.out.println(grades[0]);
    }
}

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How To Access The Element Of Array

You can use an array index to access the element of an array.

Note: An Array index always starts with 0. That means the first element of an array is at index 0.

Example

public class Main {
    public static void main(String[] args) {
    // create an array
    String []  names = {"Anar", "Rama", "Rachana", "Ram", "Munu"};
    // accessing each array elements
    System.out.println("Name at index 0 "+ names[0]);
    System.out.println("Name at index 1 "+ names[1]);
    System.out.println("Name at index 2 "+ names[2]);
    System.out.println("Name at index 3 "+ names[3]);
    System.out.println("Name at index 4 "+ names[4]);
    }
}

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Change Array Element

You can change the array element’s value by using the array index.

Example

public class Main {
    public static void main(String[] args) {
       // Array Example
        String []  names = {"Anar", "Rama", "Rachana", "Ram", "Munu"};
        names[0] = "Hari Sharma"; // It will change Anar Singh Basnet to Hari Sharma
        System.out.println("Name at index 0 "+ names[0]);
    }
}

Show Output

Find Length Of Array

You can find the array’s length using the length method.

Example

public class Main {
    public static void main(String[] args) {
       // Array Example
        String []  names = {"Anar", "Rama", "Rachana", "Ram", "Munu"};
        names[0] = "Hari Sharma"; // It will change Anar Singh Basnet to Hari Sharma
        System.out.println(names.length); // output will be 5
    }
}

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Loop Through Array

You can also loop through each element of the array. You can use for loop and length property to specify how many times the loop will run.

public class Main {
    public static void main(String[] args) {
          // create an array
            String []  names = {"Anar", "Rama", "Rachana", "Ram", "Munu"};
            // looping each array elements
            for(int i = 0; i< names.length; i++){
                System.out.println("Name at index "+ i +" "+ names[i]);
            }
    }
}

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Using Foreach

There is also foreach loop that is used exclusively to loop through elements in arrays.

Example

public class Main {
    public static void main(String[] args) {
         // Array Example
        String []  names = {"Anar", "Rama", "Rachana", "Ram", "Munu"};
        for(String name: names){
            System.out.println("Name "+ name);
        }
    }
}

Show Output

Example: Find sum and average of array element

public class Main {
    public static void main(String[] args) {
         int[] numbers = {1, 2, 5, 100, 9};
            int total = 0;
            Double avg;
            
            // access all elements using for each loop
            // add each element in total
            for (int number: numbers) {
              total += number;
            }
           
            // get the total number of elements
            int arrayLength = numbers.length;
         
            // calculate the avg
            // convert the avg from int to double
            avg =  ((double)total / (double)arrayLength);
         
            System.out.println("Total is = " + total);
            System.out.println("Average is = " + avg);
    }
}

Show Output