java define a generic class that produces

1
2List list = new ArrayList();
3list.add("abc");
4list.add(new Integer(5)); //OK
5
6for(Object obj : list){
7	//type casting leading to ClassCastException at runtime
8    String str=(String) obj; 
9}
10

1
2List<String> list1 = new ArrayList<String>(); // java 7 ? List<String> list1 = new ArrayList<>(); 
3list1.add("abc");
4//list1.add(new Integer(5)); //compiler error
5
6for(String str : list1){
7     //no type casting needed, avoids ClassCastException
8}
9