Get the ArrayList<String> from ArrayList<CustomClass> (LF method to return string data as array instead of foreach)

Question

Here's my custom Class (for readability I translated names and left away constructor etc)

public class MyClass {
    private long id;
    private String name, description;
    private int pictureId;
    ...
}

So I use this Class to store all data as an ArrayList<MyClass>

ArrayList<MyClass> items = getResources(); //fills the arraylist

I'd like to return all it's names.

Is it possible to write a custom method like ArrayList<String> names = items.getAllNames();? Because I have not idea where to put the logic to address the ArrayList and not the Class.

getAllNames()
{
    for (MyClass item : items){
        names.add(item.getName());
    }
}

Putting foreach lines everytime I need something from the ArrayList works, but it looks so messy. Is there a clean way to solve this?

Solution 1

You have to provide getters of your custom class MyClass and I use List interface as a returned type instead of ArrayList as it is more flexible.
You can try this one and let me know in case of any concern.
Please find the code snippet:

 import java.util.ArrayList;
 import java.util.List;
   class Test{

        private List<MyClass> getResources() {
            // TODO Auto-generated method stub
                // Use your business logic over here
              ----------------------------------
            return new ArrayList<MyClass>();
        }
        // This is your method which will returns all the names
        public List<String> getAllNames(){
            List<String> names = new ArrayList<String>();
            List<MyClass> items = getResources();
            for (MyClass myClass : items) {
                names.add(myClass.getName());
            }
            return names;
        }
    }

Here is your bean class MyClass, I just added getters and setters over here.

    public class MyClass {
        private long id;
        private String name;
        private String description;
        private int pictureId;

        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }


     -------------------------------------
    }

Solution 2

You'll have to create a method which iterates over all elements in your arraylist and adds every name to a second list which you'll return. I haven't read into lambda expressions for Java yet, but if I recall anything from my C# experience then you might be able to do this with Java 8.

public List<String> getNames(){
  List<String> names = new ArrayList<>();
  List<MyClass> elements = getElements();

  for(MyClass s : elements){
     names.add(s.getName());
  }

  return names;
}

Solution 3

try to follow this structure :

public class MyClass {
        private long id;
        private String name, description;
        private int pictureId;
        ...
    }

    public class Itemlist {
        public ArrayList<MyClass> items = new ArayList<MyClass>();

    public ArrayList<String> getAllNames()
    {
        ArrayList<String> names= new ArrayList<String>();
        for (MyClass item : items){
            names.add(item.getName());
        }
    return names;
    }