Trying to return a Hashtable object

Question

Hi,
I'm trying to return a Hashtable object from a method defined as:
public static Hashtable getValues(String str){
In the calling method, I'm using:
Hashtable<Object,Object> table=new Hashtable<Object,Object>();
table=(Hashtable<Object,Object>)Test.getValues(str);
I get the compiler warning as shown below:
Note: App.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Upon compiling with -Xlint:unchecked option, I get:
App.java:10: warning: [unchecked] unchecked cast
found : java.util.Hashtable
required: java.util.Hashtable<java.lang.Object,java.lang.Object>
table=(Hashtable<Object,Object>)Test.getValues(str);
^
How can I correct this?
Thanks.
Vijay

Answer 1

were your method to return a Map<Object, Object> rather than a HashMapyou could transparently return either a HashMap or a HashTable - or anything else that implements the Map interface - without changing any of the code that actually calls this method. you will still, obviously, need to instantiate one inside the method
hence the mantra "code to an abstraction, not a concrete type"