➕ Java: How to Find the Sum of Array Elements

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🧲 Introduction – Why Sum Array Elements in Java?

Adding up all elements in an array is a common task in Java, whether you’re calculating totals in a shopping cart, summing up scores, or analyzing data. It helps you practice loops, arrays, and accumulator patterns, which are critical for algorithmic thinking.

✅ In this guide, you’ll learn:

• How to sum elements in a Java array
• Multiple approaches: for-loop, enhanced for-loop, Arrays.stream()
• Handling both integer and double arrays
• Best practices and performance notes

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🧮 Method 1: Sum Using a for Loop

public class ArraySum {
    public static void main(String[] args) {
        int[] numbers = {10, 20, 30, 40};
        int sum = 0;

        for (int i = 0; i < numbers.length; i++) {
            sum += numbers[i];
        }

        System.out.println("Sum of array elements: " + sum);
    }
}

✅ Explanation:

• int sum = 0; initializes the accumulator.
• Loop iterates through the array using index i.
• Each element is added to sum.

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🔁 Method 2: Enhanced for Loop (for-each)

public class ArraySumEnhanced {
    public static void main(String[] args) {
        int[] nums = {5, 10, 15, 20};
        int sum = 0;

        for (int num : nums) {
            sum += num;
        }

        System.out.println("Sum: " + sum);
    }
}

✅ Explanation:

• More concise than a traditional for loop.
• Ideal when index isn’t needed.
• Automatically iterates through each value.

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🚀 Method 3: Sum Using Arrays.stream()

import java.util.Arrays;

public class ArraySumStream {
    public static void main(String[] args) {
        int[] nums = {3, 6, 9, 12};
        int sum = Arrays.stream(nums).sum();

        System.out.println("Total Sum: " + sum);
    }
}

✅ Explanation:

• Arrays.stream(nums) creates an IntStream.
• .sum() returns the total sum of the stream.
• Cleanest and most functional approach.

💡 Note: Available since Java 8.

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🧮 Sum of Double Array Elements

public class DoubleArraySum {
    public static void main(String[] args) {
        double[] prices = {99.99, 149.50, 200.25};
        double total = 0;

        for (double price : prices) {
            total += price;
        }

        System.out.println("Total: " + total);
    }
}

✅ Explanation:

• Works similarly with double[] arrays.
• Use double as accumulator.

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🧼 Best Practices

• ✅ Use for-each for readability when index isn’t required.
• ✅ Use Arrays.stream() for concise Java 8+ code.
• ⚠️ Validate array length before performing operations.
• ✅ Use double when working with floating-point values.

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📌 Summary – Sum Array Elements in Java

Summing array elements is a fundamental operation every Java developer must master. Java gives you multiple approaches depending on your style and Java version — from classic loops to modern streams.

🧾 Key Takeaways:

• Use a loop to accumulate values in a variable.
• Use for-each for clean and readable code.
• Use Arrays.stream().sum() for functional-style coding.
• Always initialize your sum variable properly (0, 0.0).

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❓FAQs – Sum of Array in Java

❓ How do I sum values in an array in Java?

Loop through the array using a for or for-each loop, or use Arrays.stream().

❓ What is the best way to sum a large array?

Use Arrays.stream() for concise code, or a loop for performance in tight control situations.

❓ Can I use .sum() for a double[] array?

Yes, but you’ll need DoubleStream:

double sum = Arrays.stream(array).sum();

❓ What happens if the array is empty?

Sum will be 0 by default. Avoid operations if null.

❓ Can I sum array elements conditionally?

Yes. Use streams with filters:

int sum = Arrays.stream(nums).filter(n -> n > 10).sum();

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