Book notes

The Adapter Pattern converts the interface of a class into another interface the clients expect. Adapter lets classes work together that couldn’t otherwise because of incompatible interfaces.

object adpater:

class adpater:

java 不支持多重继承，所以无法使用 class adpater

Example

用 java enumeration 实现 iterator 接口，这样在 client code 中可以像使用 iterator 一样使用：

public class EnumerationIterator implements Iterator<Object> {
	Enumeration<?> enumeration;
 
	public EnumerationIterator(Enumeration<?> enumeration) {
		this.enumeration = enumeration;
	}
 
	public boolean hasNext() { // delegate iterator's hasNext() to enumeration hasMoreElements()
		return enumeration.hasMoreElements();
	}
 
	public Object next() { // delegate iterator's next() to enumeration nextElement()
		return enumeration.nextElement();
	}
 
	public void remove() { // enumeration 无法 支持 iterator 的 remove() 操作，所以 throw exception
		throw new UnsupportedOperationException();
	}
}

test code:

public class EnumerationIteratorTestDrive {
	public static void main (String args[]) {
		Vector<String> v = new Vector<String>(Arrays.asList(args));
		Iterator<?> iterator = new EnumerationIterator(v.elements());
		while (iterator.hasNext()) {
			System.out.println(iterator.next());
		}
	}
}