What is Load Factor in HashMap?

The Load Factor in a HashMap defines how full the HashMap can get before its capacity is automatically increased (resized).

In simple terms:

👉 Load Factor controls when HashMap should grow to maintain good performance.

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🔹 Default Load Factor

The default load factor value in Java HashMap is:

0.75 (75%)

This means when the HashMap becomes 75% full, it will resize automatically.

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🔹 How It Works

Formula:

Threshold = Capacity × Load Factor

Example:

• Initial Capacity = 16

• Load Factor = 0.75

Threshold = 16 × 0.75 = 12

👉 When 12 entries are inserted, HashMap resizes (capacity becomes 32).

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🔹 Why Load Factor is Important?

It balances between:

Default value 0.75 provides the best balance between memory and performance.

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🔹 Resizing Process

When threshold is reached:

1. HashMap capacity doubles

2. All elements are rehashed

3. New bucket indexes are calculated

This process is called Rehashing.

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🔹 Custom Load Factor Example

HashMap<Integer, String> map =
        new HashMap<>(32, 0.5f);

Here:

• Initial capacity = 32

• Load factor = 0.5 (resizes earlier)

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