JavaHow-ToBeginner · 3 min read

How to Find Length of Array in Java: Simple Guide

In Java, you find the length of an array using the array.length property. This returns the number of elements in the array as an integer.

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Syntax

To get the length of an array, use the array.length property. Here, array is the name of your array variable.

array: your array variable
length: a property that holds the size of the array

java

int length = array.length;

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Example

This example creates an array of integers and prints its length using array.length.

java

public class ArrayLengthExample {
    public static void main(String[] args) {
        int[] numbers = {10, 20, 30, 40, 50};
        System.out.println("Length of array: " + numbers.length);
    }
}

Output

Length of array: 5

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Common Pitfalls

One common mistake is trying to use array.length() as if it were a method. In Java, length is a property, not a method, so it has no parentheses.

Also, length works only for arrays, not for collections like ArrayList. For collections, use size() method instead.

java

public class CommonPitfalls {
    public static void main(String[] args) {
        int[] arr = {1, 2, 3};
        // Wrong: arr.length() - this causes a compile error
        // Correct:
        int len = arr.length;
        System.out.println("Array length: " + len);
    }
}

Output

Array length: 3

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Quick Reference

Concept	Usage	Notes
Array length	array.length	Property, no parentheses
ArrayList size	arrayList.size()	Method, requires parentheses
String length	string.length()	Method, requires parentheses

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Key Takeaways

Use array.length to get the size of an array in Java.

length is a property, not a method, so do not use parentheses.

For collections like ArrayList, use size() method instead.

Remember that length works only with arrays, not with strings or collections.

Always check the type of your data structure to use the correct way to get its size.