Customizing android ListView items

Question

I have a question about customizing android ListView items:

I was following this tutorial: http://codehenge.net/blog/2011/05/customizing-android-listview-item-layout/

The first part, with normal R.android.simple_text_item_1 worked fine for me, so I get my ListView with Strings in every row.

Then I moved on and tried to modify the items of my ListView like described:

1. I defined this XML data for my list items. Its a LinearLayout that holds only two TextViews

   <?xml version="1.0" encoding="utf-8"?>
   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:orientation="horizontal" >
   
   <TextView
       android:id="@+id/username"
       android:layout_width="match_parent"
       android:layout_height="wrap_content" />
   
   <TextView
       android:id="@+id/email"
       android:layout_width="match_parent"
       android:layout_height="wrap_content" />
   
   </LinearLayout>
   

2. I defined a data class UserRecord, that simply gives me the abiltity to create objects which consist of a name and an email adress

   public class UserRecord {
       public String username;
       public String email;
   
       public UserRecord(String username, String email) {
       this.username = username;
       this.email = email;
       }
   }
   

3. I copied the whole adapterclass, but I got one error, the line where I commented

   public class UserItemAdapter extends ArrayAdapter<UserRecord> {
   private ArrayList<UserRecord> users;
   
   public UserItemAdapter(Context context, int textViewResourceId, ArrayList<UserRecord>     users) {
   super(context, textViewResourceId, users);
   this.users = users;
   }
   
   @Override
   public View getView(int position, View convertView, ViewGroup parent) {
       View v = convertView;
       if (v == null) {
       //In the following line I get the error: "The method getSystemService is undefined
       //for type UserItemAdapter
       LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
       v = vi.inflate(R.layout.list_item, null);
       }
   
       UserRecord user = users.get(position);
       if (user != null) {
           TextView username = (TextView) v.findViewById(R.id.username);
           TextView email = (TextView) v.findViewById(R.id.email);
   
       if (username != null) {
           username.setText(user.username);
       }
   
       if(email != null) {
           email.setText("Email: " + user.email );
       }
   }
   return v;
   }
   }
   

4. I changed my onCreate method in the MainActivity like follows, maybe here's the fault.

       protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
   
   ArrayList<UserRecord> users = new ArrayList<UserRecord>();
   UserRecord a = new UserRecord("a","b");
   users.add(a);
   
   ListView listView = (ListView) findViewById(R.id.listView1);
   
   //The following adapter worked fine when using a String array
   //listView.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, items));
   
   //This adapter doesn't work I guess :(
   listView.setAdapter(new UserItemAdapter(this, R.layout.list_item, users));
   
   }
   

Can anyone tell me, where my fault is? If I try to launch my app, it doesn't even start and my emulator says "unfortunately closed blabla". -.-

Answer 1

LayoutInflater is a systemService which is used to inflate layouts like the layout for your list item.In order to access any system service,you need some time of context.hence try this.

public class UserItemAdapter extends ArrayAdapter<UserRecord> {
private ArrayList<UserRecord> users;
private Context context

public UserItemAdapter(Context context, int textViewResourceId, ArrayList<UserRecord>             users) {
super(context, textViewResourceId, users);
this.context=context;
this.users = users;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
//In the following line I get the error: "The method getSystemService is undefined
//for type UserItemAdapter
LayoutInflater vi = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.list_item, null);
}

UserRecord user = users.get(position);
if (user != null) {
    TextView username = (TextView) v.findViewById(R.id.username);
    TextView email = (TextView) v.findViewById(R.id.email);

if (username != null) {
    username.setText(user.username);
}

if(email != null) {
    email.setText("Email: " + user.email );
}
}
return v;
}
}