Android Arraylist find index

Question

I have an ArrayList of object in my Fragment.

ArrayList<MenuListItem> menuItems = new ArrayList<MenuListItem>();
menuItems.add(new MenuListItem("Newsfeed", 20));
menuItems.add(new MenuListItem("FriendsRequest", 1));
menuItems.add(new MenuListItem("Messages", 2));

private class MenuListItem {
    public String label;
    public int count;

    public MenuListItem(String label, int count) {
        this.label = label;
        this.count = count;
    }
}

How can I find the index of object that has the label value "Messages" in my ArrayList from my Activity.

Алексей · Accepted Answer · 2014-01-10 19:46:58Z

4

have you try to iterate through elements of menuItems?

something of this sort:

for(MenuListItem menuListItem : menuItems){
    if (menuListItem.label.equals(<what you are looking for>){
        <do something>
        break; // in case when 1st occurence is sufficient
    }
}

side note (not related make your members private and add accessors for them)

Edit: just noticed that you are looking for an index, what i have included is to get an MenuListItem what you can do is iterate and return index if you want.

answered Jan 10, 2014 at 19:46

Алексей

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Comments

upog · Accepted Answer · 2014-01-10 19:49:50Z

3

try

        String search="Messages";
        for(int i=0;i<menuItems.size();i++){
            if(menuItems.get(i).label.equalsIgnoreCase(search)){
                System.out.println("Index " + i);
                break;
            }
        }

answered Jan 10, 2014 at 19:49

upog

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Comments

Yaroslav Mytkalyk · Accepted Answer · 2014-01-10 19:47:59Z

2

public static int indexOf(final List<MenuListItem> menuItems, final String what) {
    final int size = menuItems.size();
    for (int i = 0; i < size; i++) {
        final String label = menuItems.get(i).label;
        if (label != null && label.equals(what)) {
            return i;
        }
    }
    return -1;
}

answered Jan 10, 2014 at 19:47

Yaroslav Mytkalyk

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Comments

Ragunath Jawahar · Accepted Answer · 2014-01-16 20:46:09Z

0

There's a easier and standard way to do this.

Eclipse

Right-click inside MenuListItem class and select Source -> Generate hashCode() and equals() once you are done generating the implementations of these methods. You can use ArrayList.indexOf(Object) to get the index of the item you are looking for.

IntelliJ or Android Studio

Right-click inside your editor and click on Generate and from the dialog that pops up, select hashCode() and equals().

The Collections framework has made things easier for you already. Why not leverage it instead of writing loops to find objects? :)

PS: This can be hand written, but this is something best left to the IDE. Because having too many attributes makes it tricky to get it right the first time.

edited Jan 16, 2014 at 20:46

answered Jan 16, 2014 at 20:20

Ragunath Jawahar

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4 Comments

positivevibesonly Over a year ago

I'm using Android Studio. I checked and it is not possible here.

Ragunath Jawahar Over a year ago

No matter what, you could do that with Android Studio too. hashCode() and equals() are methods inherited from the Object class. You can do it manually, but it's a task best left to the IDE - Eclipse, Netbeans or IntelliJ.

Ragunath Jawahar Over a year ago

@Rani, this is how you do it with IntelliJ - jetbrains.com/idea/webhelp/…

positivevibesonly Over a year ago

I have to find the index of the variable and not the object itself. That's why I had to loop.

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