ListView & Array Adapters

Understanding ListView .

List View is used in order to create such a layout which has some content into it and the respective contents is

displayed as a list .

examples : Contacts , Gmail , Messages .

Creating a List .

• Build a new Android project .

• Open up activity_main.xml & add ListView into it .

• Set height and width to match_parent & give that view a respective Id . (So , that your list can be displayed in full screen) .

Now , You'll get a list rendered on your design pane of the android .

    <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.codingblocks_projects.stoned_coder.listview.MainActivity">

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </ListView>

    </RelativeLayout>

Great , Now we've a list view let's add the contents that you want to display into the list .

Adding Contents to List

• Open up , MainActivity.java file and inside your onCreate() method create a String[] and name that as per your choice , and populate that String with some values .

String[] fruits = {"Peach" , "Mango" , "Apple" , "Kiwi" , "Orange"};

So , The problem occurs is that we can't arbitrarily add this String[] to the respective list view .

In order to solve this issue there's an interface in android called ArrayAdapters.

What ArrayAdapters does that it binds your values into the list view .

ListAdapter fruits = new ArrayAdapter<>(this,android.R.layout.simple_list_item_1 , fruits);

Now the arguments that this adapter takes ;

• this : this is a keyword used for getting the context .
• android.R.layout.android.R.layout.simple_list_item_1 : It's a simple list item stored in android by default
• fruits : respective String[] , which we want to get values from .

Setting up the Adapter

• First you've to get the reference of the respective ListView by calling findViewById() method.

• Then you can simply set the adapter by calling setadapter() method , which takes one argument which is the adapter .

    ListView list = (ListView)findViewById(R.id.listView);
    list.setAdapter(FruitsAdapter)

Now , when you run your application the list will come up on the device screen like this .