Thread: Variable Type-Checking

Is it possible to write a method whose parameter type is dependent on another parameter? In other words, if I had:

void set(F fieldtype, V value);

and the type of value will be checked at compile-time against the value of fieldtype (however fieldtype is implemented)

I got the "reflection" part, .

Truth is, I'm actually refactoring code right now because the way we've implemented it (using J2SE) is we use method overloading to implement it. Basically, we use:

function1(FieldType1, ValueType1);
function2(FieldType2, ValueType2);
...
functionN(FieldTypeN, ValueTypeN);

which implements the same functionality but are able to use Java's method signature resolution at compile-time. I was hoping it could be made generic.

I tried the following snippet and it's not working as I was hoping it would, I'm coding out of ignorance right now:

package blah;
 
import java.util.Hashtable;
import java.util.Map;
 
public class TestModel {
	private Map<Object, Object> container = new Hashtable<Object, Object>();
 
	public static void main(String[] args) {
		TestModel v = new TestModel();
		v.add("hello", new Integer(2)); // There should be a compile-time error here
		v.add("hello", "there"); // But not here
		System.out.println("Value = " + v.getContainer().get("hello"));
	}
 
	public<K> void add(K fieldType, K value) {
		container.put(fieldType, value);
	}
	public void setContainer(Map<Object, Object> container) {
		this.container = container;
	}
 
	public Map<Object, Object> getContainer() {
		return container;
	}
}

Originally Posted by copeg

a) Define your class to be Generic

public class TestModel<K>{

b) no need for the generic near the public

public void add(K fieldType, K value)//remove the 'public<K>'

But this is tying down the class type for value at the time the model variable is defined. I was hoping to tie it down to the fieldType parameter at compile-time. Note the two usage examples I had and the expected results:

v.add("hello", new Integer(2)); // There should be a compile-time error here
v.add("hello", "there"); // But not here