Java Array Operations – Access, Modify, and Traverse Arrays

Arrays are fundamental in Java for storing multiple values in a single variable. To make the most of arrays, you need to access, modify, and traverse them efficiently.

1. Accessing Array Elements

Each element in an array can be accessed using its index.
Index starts from 0.

Example:

public class AccessArray {
    public static void main(String[] args) {
        int[] numbers = {10, 20, 30, 40, 50};

        System.out.println("First element: " + numbers[0]); // 10
        System.out.println("Third element: " + numbers[2]); // 30
    }
}

⚠️ Accessing an index outside the array bounds throws ArrayIndexOutOfBoundsException.

2. Modifying Array Elements

You can update an array element by assigning a new value to a specific index.

Example:

public class ModifyArray {
    public static void main(String[] args) {
        int[] scores = {90, 80, 70, 60};

        scores[2] = 75; // Change the third element from 70 to 75

        for(int i = 0; i < scores.length; i++) {
            System.out.println("Score " + i + ": " + scores[i]);
        }
    }
}

Output:

Score 0: 90
Score 1: 80
Score 2: 75
Score 3: 60

3. Traversing Arrays

Traversing means visiting each element of an array to process it. There are multiple ways to traverse arrays:

a) Using a `for` loop

int[] numbers = {10, 20, 30, 40, 50};

for(int i = 0; i < numbers.length; i++) {
    System.out.println("Element at index " + i + ": " + numbers[i]);
}

b) Using an enhanced `for-each` loop

for(int num : numbers) {
    System.out.println(num);
}

The enhanced for loop is simpler and more readable, especially for read-only operations.

c) Using `Arrays.toString()` (for quick printing)

import java.util.Arrays;

System.out.println(Arrays.toString(numbers)); // [10, 20, 30, 40, 50]

4. Common Array Operations

Length of Array

System.out.println("Array length: " + numbers.length); // 5

Sum of Elements

int sum = 0;
for(int num : numbers) {
    sum += num;
}
System.out.println("Sum: " + sum); // 150

Finding Maximum and Minimum

int max = numbers[0];
int min = numbers[0];

for(int num : numbers) {
    if(num > max) max = num;
    if(num < min) min = num;
}

System.out.println("Max: " + max + ", Min: " + min); // Max: 50, Min: 10

Searching for an Element

int target = 30;
boolean found = false;

for(int num : numbers) {
    if(num == target) {
        found = true;
        break;
    }
}

System.out.println(found ? "Found" : "Not Found"); // Found

5. Edge Cases

a) Empty Array

int[] empty = {};
System.out.println("Length: " + empty.length); // 0
// Accessing any index will throw ArrayIndexOutOfBoundsException

b) Single-element Array

int[] single = {100};
System.out.println(single[0]); // 100

c) Array with Duplicate Values

int[] duplicates = {1, 2, 2, 3};
System.out.println(Arrays.toString(duplicates)); // [1, 2, 2, 3]

d) Object Array with Null Values

String[] names = {"Alice", null, "Bob"};
for(String name : names) {
    System.out.println(name);
}

e) Invalid Index

int[] arr = {1, 2, 3};
System.out.println(arr[5]); // ArrayIndexOutOfBoundsException

Points to Remember

Access array elements using indices starting from 0.
Modify elements by assigning new values to specific indices.
Traverse arrays using for loop, enhanced for-each loop, or Arrays.toString().
Array length can be obtained using array.length.
Always check array bounds to avoid ArrayIndexOutOfBoundsException.
Use loops for operations like sum, max, min, and search.

Java Array Operations – Access, Modify, and Traverse Arrays

1. Accessing Array Elements

Example:

2. Modifying Array Elements

Example:

3. Traversing Arrays

a) Using a for loop

b) Using an enhanced for-each loop

c) Using Arrays.toString() (for quick printing)

4. Common Array Operations

Length of Array

Sum of Elements

Finding Maximum and Minimum

Searching for an Element

5. Edge Cases

a) Empty Array

b) Single-element Array

c) Array with Duplicate Values

d) Object Array with Null Values

e) Invalid Index

Points to Remember

a) Using a `for` loop

b) Using an enhanced `for-each` loop

c) Using `Arrays.toString()` (for quick printing)