Copy an array using java's Arrays.copyOf() function

Use Java's Arrays.copyOf() function to copy an array

In Java programming, it is often necessary to copy an array. Java provides a convenient method Arrays.copyOf(), which can quickly and easily copy an array. This article will introduce the usage of Arrays.copyOf() and give some code examples.

The usage of Arrays.copyOf() is very simple. It has two parameters: the length of the source array and the target array. The return value of the function is a new array containing the contents of the source array.

The following is a sample code that demonstrates how to copy an array using the Arrays.copyOf() function.

public class ArrayCopyExample {
    public static void main(String[] args) {
        // 原始数组
        int[] sourceArray = {1, 2, 3, 4, 5};

        // 复制数组
        int[] targetArray = Arrays.copyOf(sourceArray, sourceArray.length);

        // 打印原始数组
        System.out.println("原始数组:");
        for (int num : sourceArray) {
            System.out.print(num + " ");
        }
        System.out.println();

        // 打印复制的数组
        System.out.println("复制的数组:");
        for (int num : targetArray) {
            System.out.print(num + " ");
        }
        System.out.println();
    }
}

The above code first defines a primitive array sourceArray and assigns it to {1, 2, 3, 4, 5}. Then use the Arrays.copyOf() function to copy the original array to the target array targetArray. Then print the original array and the copied array separately through a for loop.

Execute the above code and you will get the following output:

原始数组:
1 2 3 4 5 
复制的数组:
1 2 3 4 5 

You can see that the contents of the original array and the copied array are exactly the same. This is because the Arrays.copyOf() function creates a new array and copies the contents of the original array into the new array.

It should be noted that although the Arrays.copyOf() function can copy the contents of the source array to the target array, the source array and the target array are not the same object. In other words, modifying the element value of one array will not affect the other array.

In addition, the Arrays.copyOf() function also has an overloaded version that can specify the length and type of the target array. For example:

int[] targetArray = Arrays.copyOf(sourceArray, 10); // 创建一个长度为10的新数组

It should be noted that if the length of the target array is greater than the length of the original array, the extra part will be filled with the default value. For arrays of primitive data types, the default value is zero. For arrays of reference types, the default value is null.

To sum up, using the Arrays.copyOf() function in Java can quickly and easily copy an array. The usage of this function is very simple, you only need to pass in the length of the source array and the target array. I hope this article will help you understand the usage of Arrays.copyOf().

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