How to access to the elements inside a linkedlist in java

Question

4.00/5 (1 vote)

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I have class:

Java

public class HarddriveStorage {
...
}

I make instances of the created class:

Java

HarddriveStorage hds1 = new HarddriveStorage ();
HarddriveStorage hds2 = new HarddriveStorage ();
HarddriveStorage hds3 = new HarddriveStorage ();

Then I add them to a linked list:

Java

LinkedList hdList = new LinkedList();
hdList.add(hds1);
hdList.add(hds2);
hdList.add(hds3);

When I want to access the objects, I get a reference instead of value:

Java

hdList.get(1);

I get:

org.cloudbus.cloudsim.HarddriveStorage@578486a3

What should I do to get "hds2" for example in return?

What I have tried:

I have read documents on the web, but couldn't make it.

Posted 5-Jun-19 0:10am

Ali Majed HA

Updated 6-Jun-19 2:46am

v2

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2 solutions

Solution 2

Quote:
When I want to access the objects, I get a reference instead of value:

Quote:
What should I do to get "hds2" for example in return?

hds2 is just the name of the variable, it is not the value of the object.
get returns a reference to the object and you may use it to retrieve all the properties of such object.

Posted 5-Jun-19 0:48am

CPallini

Comments

Ali Majed HA 5-Jun-19 8:41am

How can I access to the methods and variables of "hds2" object?

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Thomas Daniels · Accepted Answer · 2019-06-05T00:34:00

Solution 1

Your method is fine. org.cloudbus.cloudsim.HarddriveStorage@578486a3 is just the string representation of the object.

Edit:

Because .get returns an Object, you have to cast the return value back to HarddriveStorage:

Java

HarddriveStorage myHD = (HarddriveStorage)hdList.get(1);

Posted 5-Jun-19 0:34am

Thomas Daniels

Updated 5-Jun-19 2:52am

v3

Comments

Ali Majed HA 5-Jun-19 8:43am

I want to access methods and variable of the object. How should I do it?

Thomas Daniels 5-Jun-19 8:44am

HarddriveStorage yourObject = hdList.get(1);
yourObject.callYourMethod();

Ali Majed HA 5-Jun-19 8:49am

If I say:
HarddriveStorage MyHD = hdList.get(1);

The error is:
"incompatible types: Object can not be converted to HarddriveStorage."

and if I say:
Object MyHD = hdList.get(1);

I can't access the methods inside HarddriveStorage.
MyHD.
just give me a limited choices.

Thomas Daniels 5-Jun-19 8:51am

Oh right, LinkedList stores objects. You have to cast the return value to HarddriveStorage like this:

HarddriveStorage myHD = (HarddriveStorage)hdList.get(1);

Ali Majed HA 5-Jun-19 9:00am

Thanks a lot my friend.

CPallini 5-Jun-19 8:57am

Suppose your HarddriveStorage has a method called brand() then you may write

HarddriveStorage h1 = (HarddriveStorage)hdlist.get(1);
String h1brand = h1.brand();

Note the cast is required because you are using a non generic container.

Ali Majed HA 5-Jun-19 8:58am

That's it! Thanks a lot.

CPallini 5-Jun-19 11:55am

You are welcome.