Introducing commonly used methods of converting Java arrays into Lists

Introduction to common methods of converting Java arrays into List

In Java development, we often encounter situations where arrays are converted into Lists. Converting an array into a List makes it easy to add, delete, modify, and check elements. This article will introduce three commonly used methods, namely using the Arrays tool class, using the ArrayList constructor, and using the addAll method of the Collections tool class.

1. Using the asList method of the Arrays tool class
   The Arrays tool class is a tool class provided in Java that contains various static methods, including the method asList that converts an array into a List. The following is a code example that uses this method to convert an array into a List:

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

public class ArrayToListExample {
    
    public static void main(String[] args) {
        String[] array = {"apple", "banana", "orange"};
        List<String> list = Arrays.asList(array);
        System.out.println(list);
    }
}

After running the above code, the output result is: [apple, banana, orange]. As you can see, through the asList method of the Arrays tool class, we can easily convert the array into a List.

It should be noted that the length of the List converted using the asList method is fixed, that is, addition and deletion operations cannot be performed. This is because the List returned by the asList method is actually an immutable List, which is just a wrapper of the original array. If you need to add or delete the converted List, you can convert it into an ArrayList or LinkedList.

2. Using the ArrayList constructor
   ArrayList is a commonly used List implementation class in Java. It provides multiple constructors, one of which accepts an array as a parameter. Through this constructor, you can easily convert an array into an ArrayList. The following is a code example that uses the ArrayList constructor to convert an array into a List:

import java.util.ArrayList;
import java.util.List;

public class ArrayToListExample {
    
    public static void main(String[] args) {
        String[] array = {"apple", "banana", "orange"};
        List<String> list = new ArrayList<>(Arrays.asList(array));
        System.out.println(list);
    }
}

After running the above code, the output result is: [apple, banana, orange]. By using the constructor of ArrayList, we can convert the array into a modifiable List, which can be added and deleted.

It should be noted that this method will create a new ArrayList object and add the elements in the array to the object. Therefore, addition and deletion operations on the converted List will not affect the original array.

3. Use the addAll method of the Collections tool class
   The Collections tool class is a tool class provided in Java that contains various static methods, including adding multiple elements to a collection at one time The method addAll. Through this method, we can add elements in the array to the List at once. The following is a code example that uses the addAll method of the Collections tool class to convert an array into a List:

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class ArrayToListExample {
    
    public static void main(String[] args) {
        String[] array = {"apple", "banana", "orange"};
        List<String> list = new ArrayList<>();
        Collections.addAll(list, array);
        System.out.println(list);
    }
}

After running the above code, the output result is: [apple, banana, orange]. By using the addAll method of the Collections tool class, we can add elements in the array to the List at once.

It should be noted that this method adds elements in the array to the specified List, so addition and deletion operations on the converted List will affect the original array.

Summary
This article introduces three commonly used methods to convert an array into a List, namely using the asList method of the Arrays tool class, using the ArrayList constructor and using the addAll method of the Collections tool class. Developers can choose the appropriate method to convert an array into a List according to their own needs.

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