Copiar arrays. Uso de la instrucción "System.arraycopy".

Código java (CopiaArray.java):

package copiaarray;

public class CopiaArray {

   public static void main(String[] args) {

      double[] array1 = new double[5];
      double[] array2 = new double[10];
      double[] array3 = new double[array1.length + array2.length];

      //rellena array1
      for (int i = 0; i < array1.length; i++) {
         array1[i] = i;
      }

      //rellena array2
      for (int i = 0; i < array2.length; i++) {
         array2[i] = Math.random();
      }

      /*
         Parametros del System.arraycopy:
         Array origen,
         Posición inicial del array origen,
         Array destino,
         Posición incial en el array de destino,
         Numero de elementos a copiar del array origen al array destino
       */
     
      System.arraycopy(array1, 0, array3, 0, array1.length);
      System.arraycopy(array2, 0, array3, array1.length, array2.length);

      //mostrar resultados
      System.out.println("\nArray1");
      for (int i = 0; i < array1.length; i++) {
         System.out.println(i + "- " + array1[i]);
      }

      System.out.println("\nArray2");
      for (int i = 0; i < array2.length; i++) {
         System.out.println(i + "- " + array2[i]);
      }

      System.out.println("\nArray3");
      for (int i = 0; i < array3.length; i++) {
         System.out.println(i + "- " + array3[i]);
      }

   }

}


Resultado:

run:

Array1
0- 0.0
1- 1.0
2- 2.0
3- 3.0
4- 4.0

Array2
0- 0.5287887048803938
1- 0.46771014928163135
2- 0.8333523729100707
3- 0.4965787587571521
4- 0.26861092247251583
5- 0.822652997195613
6- 0.5053721779352607
7- 0.896713025382418
8- 0.9093387247823286
9- 0.8910677970677133

Array3
0- 0.0
1- 1.0
2- 2.0
3- 3.0
4- 4.0
5- 0.5287887048803938
6- 0.46771014928163135
7- 0.8333523729100707
8- 0.4965787587571521
9- 0.26861092247251583
10- 0.822652997195613
11- 0.5053721779352607
12- 0.896713025382418
13- 0.9093387247823286
14- 0.8910677970677133
BUILD SUCCESSFUL (total time: 0 seconds)