Mega Code Archive
Creating Custom Enumerations
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import java.lang.reflect.Array;
import java.util.Enumeration;
class ArrayEnumeration implements Enumeration {
private final int size;
private int cursor;
private final Object array;
public ArrayEnumeration(Object obj) {
Class type = obj.getClass();
if (!type.isArray()) {
throw new IllegalArgumentException("Invalid type: " + type);
}
size = Array.getLength(obj);
array = obj;
}
public boolean hasMoreElements() {
return (cursor < size);
}
public Object nextElement() {
return Array.get(array, cursor++);
}
}
public class MainClass {
public static void main(String args[]) {
Object obj = new int[] { 2, 3, 5, 8, 13, 21 };
Enumeration e = new ArrayEnumeration(obj);
while (e.hasMoreElements()) {
System.out.println(e.nextElement());
}
try {
e = new ArrayEnumeration("Not an Array");
} catch (IllegalArgumentException ex) {
System.out.println(ex.getMessage());
}
}
}
2
3
5
8
13
21
Invalid type: class java.lang.String
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