Java Wildcards

Java Wildcards:

The question mark (?) is known as the wildcard in generic programming . It represents an unknown type. The wildcard can be used in a variety of situations such as the type of a parameter, field, or local variable; sometimes as a return type. Unlike arrays, different instantiations of a generic type are not compatible with each other, not even explicitly.

Code:

1. import java.util.List;  
2. import java.util.ArrayList;  
3.   
4.   
5. public class WildCardDemo {  
6.   
7.   
8.     public static void main(String[] args) {  
9.         // TODO Auto-generated method stub  
10.   
11.           
12.         List<Integer>integerList=new ArrayList<Integer>();  
13.         integerList.add(6);  
14.         integerList.add(3);  
15.         print(integerList);  
16.           
17.         List<String>sList=new ArrayList<String>();  
18.         sList.add("A");  
19.         sList.add("C");  
20.         print(sList);     
21.   
22.     }  
23.     public static void print(List<?> list) {  
24.         for(Object input:list){  
25.             System.out.println("Input "+input);  
26.         }  
27.   
28.           
29.     }  
30.   
31. }