Problem running code with JDK 1.5

[Unnsse Khan]

Hello there,

I haven't fooled around with the JDK 1.5, that much, yet...

Was trying to run this code sample on my G4 PowerBook (running OS X Tiger) and as you can see the Java version on my machine is set as follows:

Raven:~ untz$ echo $JAVA_HOME
/System/Library/frameworks/JavaVM.framework/Versions/1.5.0/Home
Raven:~ untz$ java -version
java version "1.5.0_02"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_02-56)
Java HotSpot(TM) Client VM (build 1.5.0_02-36, mixed mode, sharing)
Raven:~ untz$ 

Here's the code that giving me problems:

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
 
public class RentABike
{
    private String storeName;
    final List bikes = new ArrayList();
 
    public RentABike(String storeName)
    {
        this.storeName = storeName;
 
        bikes.add(new Bike("Shimano", "Roadmaster", 20, "11111", 15, "Fair"));
        bikes.add(new Bike("Cannondale", "F2000 XTR", 18, "22222", 12 , "Excellent"));
        bikes.add(new Bike("Trek", "6000", 19, "33333", 12.4, "Poor"));
    }
 
    public String toString() { return "RentABike: " + storeName; }
 
    public List getBikes()
    {
        return bikes;
    }
 
    public Bike getBike(String serialNo)
    {
        Iterator it = bikes.iterator();
 
        while (it.hasNext())
        {
            Bike bike = (Bike) it.next();
            if (serialNo.equals(bike.getSerialNo())) return bike;
        }
 
        return null;
    }
}

When I try to compile this code, this is the warning I get:

Raven:/Developer/RentABikeApp/src untz$ javac -d ../cls RentABike.java 
Note: RentABike.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Raven:/Developer/RentABikeApp/src untz$ javac -d ../cls -Xlint RentABike.java 
RentABike.java:14: warning: [unchecked] unchecked call to add(E) as a member of the raw type java.util.List
        bikes.add(new Bike("Shimano", "Roadmaster", 20, "11111", 15, "Fair"));
                 ^
RentABike.java:15: warning: [unchecked] unchecked call to add(E) as a member of the raw type java.util.List
        bikes.add(new Bike("Cannondale", "F2000 XTR", 18, "22222", 12 , "Excellent"));
                 ^
RentABike.java:16: warning: [unchecked] unchecked call to add(E) as a member of the raw type java.util.List
        bikes.add(new Bike("Trek", "6000", 19, "33333", 12.4, "Poor"));
                 ^
3 warnings
Raven:/Developer/RentABikeApp/src untz$ 

What does this all mean?

Many, many, thanks!

[Bear Bibeault]

I don't think there's any Mac-specific dimension to this, so I've moved it along to the Java in General (intermediate) forum.

[Layne Lund]

The Collections framework has been rewritten to take advantage of generics which are a new feature in Java 1.5 that add some extra type-checking. Notice that the output says these are warnings only, so you can safely ignore them for now and run your program just fine. However, I strongly encourage you to learn more about generics so that you can modify your program to take advantage of this powerful feature.

Layne

[Unnsse Khan]

Can you provide me with an example which is pertinent to the code above?

[Layne Lund]

Originally posted by Unnsse Khan:
Can you provide me with an example which is pertinent to the code above?

A quick search provides many examples already available on the Web, so I won't repeat it here. (Google is your friend!)

Layne

[Unnsse Khan]

Layne,

I think you misunderstood me... I wasn't trying to get anyone to do the work for me. The reason I asked for an example is because my trusty IDE (Eclipse) placed this before the particular method:

@SuppressWarnings("unchecked")

Thanks for the help...

Kindest regards,

[Layne Lund]

Originally posted by Unnsse Khan:
Layne,

I think you misunderstood me... I wasn't trying to get anyone to do the work for me. The reason I asked for an example is because my trusty IDE (Eclipse) placed this before the particular method:

@SuppressWarnings("unchecked")

Thanks for the help...

Kindest regards,

I'm not sure what that has to do with examples about generics. Perhaps I misunderstood what you were asking for. This looks like it may be a compiler directive to Eclipse so that it will suppress the warnings that you originally asked about. As far as I know, this line is specific to Eclipse and is not a general Java convention.

Layne