The JavaTM Tutorial

| Start of Tutorial > Start of Trail > Start of Lesson | Search Feedback Form

Trail: The Reflection API
Lesson: Working with Arrays

## Getting and Setting Element Values

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

> >     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 runtime.

> 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

| Start of Tutorial > Start of Trail > Start of Lesson | Search Feedback Form