How to Pass Array to Method in Java: Syntax and Examples

In Java, you can pass an array to a method by specifying the array type in the method parameter, like void methodName(int[] arr). Then, call the method by passing the array variable, for example, methodName(myArray).

Syntax

To pass an array to a method, declare the method parameter with the array type. For example, int[] arr means the method expects an array of integers. When calling the method, pass the array variable directly.

• Method declaration: specifies the array parameter
• Method call: passes the actual array

java

public void methodName(int[] arr) {
    // use arr inside method
}

// Calling the method
int[] myArray = {1, 2, 3};
methodName(myArray);

Example

This example shows a method that receives an integer array and prints each element. It demonstrates how to pass the array and use it inside the method.

java

public class ArrayExample {
    public static void printArray(int[] numbers) {
        for (int num : numbers) {
            System.out.println(num);
        }
    }

    public static void main(String[] args) {
        int[] myNumbers = {10, 20, 30, 40};
        printArray(myNumbers);
    }
}

Output

10
20
30
40

Common Pitfalls

Common mistakes include:

• Passing the array length or elements instead of the array variable.
• Declaring the method parameter incorrectly, such as missing the array brackets.
• Modifying the array inside the method without understanding that arrays are passed by reference.

Always pass the array variable and declare the parameter with brackets [].

java

public class PitfallExample {
    // Wrong: parameter missing []
    // public static void wrongMethod(int arr) { }

    // Correct:
    public static void correctMethod(int[] arr) {
        for (int i = 0; i < arr.length; i++) {
            arr[i] = arr[i] * 2; // modifies original array
        }
    }

    public static void main(String[] args) {
        int[] data = {1, 2, 3};
        correctMethod(data);
        for (int num : data) {
            System.out.println(num); // prints 2, 4, 6
        }
    }
}

Output

2
4
6

Quick Reference

Remember these tips when passing arrays to methods:

• Use type[] name in method parameters.
• Pass the array variable directly when calling the method.
• Arrays are passed by reference, so changes inside the method affect the original array.

Key Takeaways

Declare method parameters with array brackets, e.g., int[] arr, to accept arrays.

Pass the array variable directly when calling the method, like methodName(myArray).

Arrays are passed by reference, so changes inside the method affect the original array.

Avoid passing individual elements or array length instead of the whole array.

Always match the array type in the method parameter with the array you pass.