Working with Arrays

Getting and Setting Element Values

In most programs, to access array elements you merely use an assignment expression:

int[10] codes; 
codes[3] = 22; 
aValue = codes[3];

This technique will not work if you don't know the name of the array until run time.

Fortunately, you can use the Array class set and get methods to access array elements when the name of the array is unknown at compile time. In addition to get and set, the Array class has specialized methods that work with specific primitive types. For example, the value parameter of setInt is an int, and the object returned by getBoolean is a wrapper for a boolean type.

The sample program that follows uses the set and get methods to copy the contents of one array to another.

import java.lang.reflect.*;

class SampleGetArray {

   public static void main(String[] args) {
      int[] sourceInts = {12, 78};
      int[] destInts = new int[2];
      copyArray(sourceInts, destInts);
      String[] sourceStrgs = {"Hello ", "there ", "everybody"};
      String[] destStrgs = new String[3];
      copyArray(sourceStrgs, destStrgs);
   }

   public static void copyArray(Object source, Object dest) {
      for (int i = 0; i < Array.getLength(source); i++) {
         Array.set(dest, i, Array.get(source, i));
         System.out.println(Array.get(dest, i));
      }
   }
}

The output of the sample program is:

12
78
Hello 
there 
everybody

Working with Arrays