The class which is declared without name is called Anonymous Inner Class.
Let's see following example for better clarity.

Here, i have presented two examples :
1.Normal Interface approach
2.Using Anonymous inner class

Normal Interface Approach

package java8s;
interface Transaction
{ 
	public void withDraw(int amt);
}
class A implements Transaction
{
	public void withDraw(int amt);
	{
		System.out.println(amount  withdrawn is+amt);
	}
}
public class Example {
	public static void main(String[] args) {
 		A  ob1=new A();
 		ob1.withDraw(15000);
 	}
}

Using Anonymous Inner Class:

package  java8s;
interface Transaction
{ 
	public void withDraw(int amt);
}
public class Example {
	public static void main(String[] args) {
		Transaction  ob1=new Transaction()   //Anonymous  Inner Class
		{
			public void withDraw(int amt);
		 	{
		 		System.out.println(amount  withdrawn is+amt);
		 	}
		};
		ob1.withDraw(15000);
	}
}