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Java / Arrays

Arrays.asList(arrayIdentifier)

asList method takes an array/vararg argument and returns a fixed-size list backed by the specified array. Any modification or overwrite applied on the list will reflect on the original array and like wise.

Remember that asList is fixed size so we can not add/remove new elements to the List.

Rearranging the elements in array or the list reflects in both.

import java.util.Arrays;
import java.util.List;

public class ArraysAsListExample {

	public static void main(String[] args) {
		String[] myFruits = { "Apple", "Pineapple", "Strawberry" };

		System.out.println("The fruits available in my original Array:");

		for (String fruit : myFruits) {
			System.out.println("* " + fruit);
		}

		List<String> fruitList = Arrays.asList(myFruits);
		System.out.println("The fruits in my fixed size List:");
		for (String fruit : fruitList) {
			System.out.println("* " + fruit);
		}

		// The below lines (add and remove operation) will throw runtime
		// Exception (java.lang.UnsupportedOperationException) on the fixed
		// length list. so commented the line.
		// fruitList.add("Cherry");
		// fruitList.remove(2);

		// overwriting Apple with Cherry through the List which will be
		// reflected in the original Array.
		fruitList.set(0, "Cherry");
		// overwriting Pineapple with Banana through the original Array which
		// will be reflected in the list.
		myFruits[1] = "Banana";

		System.out.println("The fruits available in my original Array:");
		for (String fruit : myFruits) {
			System.out.println("* " + fruit);
		}

		System.out.println("The fruits in my fixed size List:");
		for (String fruit : fruitList) {
			System.out.println("* " + fruit);
		}
	}
}

Note that asList produces unexpected results with primitive arrays since List does not support primitive datatypes and it does not get autoboxed to its corresponding wrapper class.

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