Getting objects from a list

[markyoung1984]

I am very new to Java.

I have a List called siteList, which has about 65 objects of type Site. I have a for loop in which I wish to iterate through the List and call a function (test) from each Site object. I'm but quite sure how to do this. So far I have:

Code:

	for (int i=0;i<siteList.size();i++)
		{
			siteList.get(i).test(3,3);
		}

The compiler states that it cannot resolve symbol for test. Any suggestions?

[saint_jorjo]

You have to downCast to your type because siteList.get(i) is Object you have to made it like that ((Your Object)siteList.get(i)).test(3,3);
your object is the name of this class, try it

[aibtus]

Quote:

Originally Posted by markyoung1984

I am very new to Java.

I have a List called siteList, which has about 65 objects of type Site. I have a for loop in which I wish to iterate through the List and call a function (test) from each Site object. I'm but quite sure how to do this. So far I have:

Code:

	for (int i=0;i<siteList.size();i++)
		{
			siteList.get(i).test(3,3);
		}

The compiler states that it cannot resolve symbol for test. Any suggestions?

well, for starters...

Code:

         siteList.get(i)

will return an Object.... a generic object...Every class in Java is an Object and I can tell you this "test" is not a java object instance variable......

It's specific to your class maybe...a particular class ...not a generic 'Object' class.
Do something like this

Code:

         ((MyClass)siteList.get(i)).test(3,3);

Cas the returned object to MyClass --- your particular class. and the call the in stance variable on the cast

[markyoung1984]

Thanks for your replies, that works fine. My program now compiles but I have an issue when adding things to the list (siteList). My program basically reads in a line from a file and then splits it into tokens and stores these in an array temporarily. The values in this array (lineContents) are then written to an object constructor of type site. However, when doing this using the code below, I get a Null Pointer Exception. Let me know your thoughts.

Code:

List siteList;

while ((line = in.readLine()) != null){  //whilst there are lines in the file

	 StringTokenizer st = new StringTokenizer(line, ",");

	 while (st.hasMoreTokens()) {
		lineContents[tokenCount] = st.nextToken();
		tokenCount = tokenCount + 1;
	}
	//add to the sites

	siteList.add(new site(lineContents[0],lineContents[1]));
}

[saint_jorjo]

i need all source of the program