Java 25 (LTS) reference · List and ArrayList Methods

Java List set() Method

Replace the element at an index and return the old value. The list's size doesn't change.

Java 25 (LTS) Since Java 1.0

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Syntax

list.set(index, element)

Parameters

Parameter	Description
`index` int	Position to replace.
`element` E	New value.

Return value

The previous element.

Examples

Replace by index

import java.util.*;

public class Main {
    public static void main(String[] args) {
        List<String> tasks = new ArrayList<>(List.of("draft", "review", "publish"));
        String old = tasks.set(1, "edit");
        System.out.println(old + " -> " + tasks);
    }
}

Output

review -> [draft, edit, publish]

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Update every element

import java.util.*;

public class Main {
    public static void main(String[] args) {
        List<Integer> prices = new ArrayList<>(List.of(10, 20, 30));
        for (int i = 0; i < prices.size(); i++) prices.set(i, prices.get(i) * 2);
        System.out.println(prices);
    }
}