{"id":5284,"date":"2021-03-23T16:52:57","date_gmt":"2021-03-23T16:52:57","guid":{"rendered":"https:\/\/ded9.com\/?p=5284"},"modified":"2025-12-21T11:10:14","modified_gmt":"2025-12-21T11:10:14","slug":"how-to-copy-java-arrays-in-very-simple-language","status":"publish","type":"post","link":"https:\/\/ded9.com\/de\/how-to-copy-java-arrays-in-very-simple-language\/","title":{"rendered":"How to Copy Java Arrays in Very Simple Language"},"content":{"rendered":"

In this tutorial, you will learn about different methods that you can use to copy arrays (both one-dimensional and two-dimensional) in Java<\/a>.<\/span><\/span><\/p>\n

There are several techniques you can use to copy arrays in Java.<\/p>\n

\"There<\/p>\n

Copy arrays using the assignment operator<\/h2>\n

Let’s take an example,<\/p>\n

\n
    \n
  1. class CopyArray {<\/li>\n
  2. public static void main (String [] args) {<\/li>\n
  3. <\/li>\n
  4. int [] numbers = {1, 2, 3, 4, 5, 6};<\/li>\n
  5. int [] positiveNumbers = numbers;\u00a0\/\/ copying arrays<\/li>\n
  6. <\/li>\n
  7. for (int number: positiveNumbers) {<\/li>\n
  8. System.out.print (number + \u201c,\u201c);<\/li>\n
  9. }<\/li>\n
  10. }<\/li>\n
  11. }<\/li>\n<\/ol>\n<\/blockquote>\n

    Output<\/p>\n

    \n

    1, 2, 3, 4, 5, 6<\/p>\n<\/blockquote>\n

    Although this method seems quite efficient for copying arrays, there is a problem with it.<\/p>\n

    If you change the elements of one array in the example above, the elements of the other array will also change.<\/p>\n

    \n
      \n
    1. class AssignmentOperator {<\/li>\n
    2. public static void main (String [] args) {<\/li>\n
    3. <\/li>\n
    4. int [] numbers = {1, 2, 3, 4, 5, 6};<\/li>\n
    5. int [] positiveNumbers = numbers;\u00a0\/\/ copying arrays<\/li>\n
    6. <\/li>\n
    7. numbers [0] = -1;<\/li>\n
    8. for (int number: positiveNumbers) {<\/li>\n
    9. System.out.print (number + \u201c,\u201c);<\/li>\n
    10. }<\/li>\n
    11. }<\/li>\n
    12. }<\/li>\n<\/ol>\n<\/blockquote>\n

      Output<\/p>\n

      \n

      -1, 2, 3, 4, 5, 6<\/p>\n<\/blockquote>\n

      When the first element of the numbers array changes to -1, the first element of the positiveNumbers array also changes to -1 because both arrays point to the same array object.<\/p>\n

      This is called surface copy.<\/p>\n

      Most of the time, however, we need a deep copy rather than a shallow copy. A deep copy copies the values of the new array object’s properties.<\/p>\n

      2- Using the loop structure to copy arrays<\/span><\/h2>\n

      Let’s take an example:<\/p>\n

      \n
        \n
      1. import java.util.Arrays;<\/li>\n
      2. class ArraysCopy {<\/li>\n
      3. public static void main (String [] args) {<\/li>\n
      4. <\/li>\n
      5. int [] source = {1, 2, 3, 4, 5, 6};<\/li>\n
      6. int [] destination = new int [6];<\/li>\n
      7. for (int i = 0; i <source.length; ++ i) {<\/li>\n
      8. destination [i] = source [i];<\/li>\n
      9. }<\/li>\n
      10. <\/li>\n
      11. \/\/ converting array to string<\/li>\n
      12. System.out.println (Arrays.toString (destination));<\/li>\n
      13. }<\/li>\n
      14. }<\/li>\n<\/ol>\n<\/blockquote>\n

        Output<\/p>\n

        \n

        [1, 2, 3, 4, 5, 6]<\/p>\n<\/blockquote>\n

        Here, the loop iterates over the elements of the source array. In each iteration, the corresponding component of the source array is copied to the destination array.<\/p>\n

        The source and destination arrays do not share the same reference (i.e., they are not a deep copy). This means that if the elements of one array (source or destination) change, the elements of the other array will remain unchanged.<\/p>\n

        The toString () method converts arrays to strings (for output only).<\/p>\n

        There is a better way (better than loops) to copy arrays in Java using arraycopy () and copyOfRange ().<\/p>\n

        3. Copy arrays with arraycopy ()<\/span><\/h2>\n

        The System class contains an arraycopy () method that allows you to copy data from one array to another.<\/p>\n

        The arraycopy () method is efficient and flexible. This method enables you to copy a specific portion of the source array to the destination array.<\/strong><\/p>\n

        \n

        public static void arraycopy (Object src, int srcPos,<\/p>\n

        Object dest, int destPos, int length)<\/p>\n<\/blockquote>\n

        here,<\/p>\n