Add Items To ListView Dynamically: Android Tutorial

It can be difficult setting up a ListView in Android using the very basic tools available. It might take awhile getting your head around how the different basic adapters work, so often people just create custom adapters to get things how they want them to be. It's a brute-force method and takes more time than is necessary; all one needs to know is how to use ListActivity and ArrayAdapter to make things shorter and sweeter.

So, let's create an item list which allows us to add text items to it as well as remove them. I'll call the application project "DynamicLV". The main activity will be called "MainActivity" and the layout for it will be called "activity_main." I've set "onClick" in the xml layout file...

activity_main.xml

<?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="vertical" >     <LinearLayout         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:orientation="horizontal"         android:gravity="center">         <Button             android:id="@+id/addItem"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:text="Add Item"             android:onClick="onClick"/>         <Button             android:id="@+id/deleteItem"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:text="Remove Item"             android:onClick="onClick"/>     </LinearLayout>         <EditText             android:id="@+id/editText"             android:layout_width="fill_parent"             android:layout_height="wrap_content"             android:hint="Enter New Item"/>"         <ListView               android:id="@android:id/list"               android:layout_width="match_parent"               android:layout_height="wrap_content" >         </ListView> </LinearLayout>

 Pay attention to the ListView id; this is how we name it when using ListActivity (See MainActivity below)

MainActivity.java

import java.util.ArrayList; import java.util.List; import android.os.Bundle; import android.app.Activity; import android.app.ListActivity; import android.view.Menu; import android.view.View; import android.widget.ArrayAdapter; import android.widget.EditText; public class MainActivity extends ListActivity {                    EditText et;                                       @Override                    protected void onCreate(Bundle savedInstanceState) {                    　　　　super.onCreate(savedInstanceState);                    　　　　setContentView(R.layout.activity_main);                    　　　　et = (EditText) findViewById(R.id.editText);                                                                  // use List and not String[]                    　　　　List values = new ArrayList();                                                                  // simple_list_item_1 is a default row-item layout for ListAdapter                         　　　　ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,                                               android.R.layout.simple_list_item_1, values);                    　　　　setListAdapter(adapter);                    }                                       public void onClick(View view) {                            // we're going to add directly to the adapter, so declare it within the method                            ArrayAdapter<String> adapter = (ArrayAdapter<String>) getListAdapter();                            String item;                            //as with the adapter, we're going to add to the List, so declare it                            List myList = new ArrayList();                            switch (view.getId()) {                            case R.id.addItem:                                      item = et.getText().toString();                                      myList.add(item);                                      adapter.add(item);                                      et.setText("");                                      break;                            case R.id.deleteItem:                                      if (getListAdapter().getCount() > 0) {                                          // remove the last item added to the list                                          item = (String) getListAdapter().getItem(getListAdapter().getCount()-1);                                          myList.remove(item);                                          adapter.remove(item);                                      }                                      break;                                   }                            adapter.notifyDataSetChanged();                    }                    @Override                    public boolean onCreateOptionsMenu(Menu menu) {                                      // Inflate the menu; this adds items to the action bar if it is present.                                      getMenuInflater().inflate(R.menu.main, menu);                                      return true;                    } }

So, now if we run our application, we have an empty list waiting to be edited...

Now, we add 5 items...

And, finally we remove the last item because, well... it's rubbish, isn't it?...

Using ListActivity and ListAdapter is pretty easy once you get your head around it. As always, thanks for following, and let me know if you have any questions or concerns about this tutorial. Cheers!

NOTE: Don't forget to read up on the relevant API...

• ListAdapter | Android
• ArrayAdapter | Android
• ListActivity | Android