This document provides instructions for creating a basic ToDo list Android application from scratch. It describes creating an Android project called ToDoList, modifying the main layout file to include an EditText, Button, and ListView within a LinearLayout, and giving each widget an ID. It then explains getting references to these widgets in the main activity class, creating an ArrayList to store todo items and an ArrayAdapter to bind the list to the ListView. Finally, it details adding an onClickListener to the button to add new items to the ArrayList and notify the adapter of changes. Running the application should display an editable todo list.

1. Welcome!

2. Today we are going
to create a new
Android Application
from scratch.

3. Create a new
Android Project with
a name ToDoList
If you have problems, look through
previous tutorial.

4. Modify the main layout (activity_main.xml in /res/layout)
to include ListView, Button and EditText within a
LinearLayout.
<?xml version= "1.0" encoding = "utf-8" ?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation = "vertical"
android:layout_width = "fill_parent"
android:layout_height = "fill_parent">
<EditText
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="New To Do Item" />
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text = "Add" />
<ListView
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>

5. Its important to give Button, EditText and ListView
controls IDs so you can get reference to them in the
code.
<?xml version= "1.0" encoding = "utf-8" ?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation = "vertical"
android:layout_width = "fill_parent"
android:layout_height = "fill_parent">
<EditText
android:id = "@+id/editText"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="New To Do Item" />
<Button
android:id = "@+id/buttonAdd"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text = "Add" />
<ListView
android:id = "@+id/listView"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>

6. Now open your main Activity class (MainActivity.java at
/ src / com. … / ).
Default main activity prob looks like:
package com.example.todolist;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@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;
}
}
Takes layout from
resource folder we
have made recently.

7. We will work only with onCreate method. Firstly get
references to the ListView and EditText using
findViewById.
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Inflate activity view
setContentView(R.layout.activity_main);
// Get reference to UI
ListView myListView = (ListView)findViewById(R.id.listView);
EditText myEditText = (EditText)findViewById(R.id.editText);
Button buttonAdd = (Button)findViewById(R.id.buttonAdd);
}

8. Now we need to create ArrayList of Strings to store
each to-do list item. (check out about array list if you are not sure)
And ArrayAdapter to store content in ListView.
(check out about array list if you are not sure)
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Inflate activity view
setContentView(R.layout.activity_main);
// Get reference to UI
ListView myListView = (ListView)findViewById(R.id.listView);
EditText myEditText = (EditText)findViewById(R.id.editText);
Button buttonAdd = (Button)findViewById(R.id.buttonAdd);
// Create the array list of to-do items
ArrayList<String> todoItems = new ArrayList<String>();
// Create the array adapter to bind the array to the listview
ArrayAdapter<String> aa;
}

9. Next step to bind string array with array adapter and
with listView
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Inflate activity view
setContentView(R.layout.activity_main);
// Get reference to UI
ListView myListView = (ListView)findViewById(R.id.listView);
EditText myEditText = (EditText)findViewById(R.id.editText);
Button buttonAdd = (Button)findViewById(R.id.buttonAdd);
// Create the array list of to-do items
ArrayList<String> todoItems = new ArrayList<String>();
// Create the array adapter to bind the array to the listview
ArrayAdapter<String> aa;
aa = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,
todoItems);
// Bind the array adapter to the listView
myListView.setAdapter(aa);
}
Defining array
adapter through
current object,
layout item and
array list.

10. The final step is to make to-do list functional.
Add onKeyListener to the EditText that listens for a
“D-pad center button” and add item to string array list.
Add final label for
variables used inside
OnKeyListner to make
sure they won't going
to change
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Inflate activity view
setContentView(R.layout.activity_main);
// Get reference to UI
ListView myListView = (ListView)findViewById(R.id.listView);
final EditText myEditText =
(EditText)findViewById(R.id.editText);
final Button buttonAdd = (Button)findViewById(R.id.buttonAdd);
// Create the array list of to-do items
final ArrayList<String> todoItems = new ArrayList<String>();
// Create the array adapter to bind the array to the listview
final ArrayAdapter<String> aa;
aa = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,
todoItems);
// Bind the array adapter to the listView
myListView.setAdapter(aa);
buttonAdd.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
todoItems.add(0, myEditText.getText().toString());
aa.notifyDataSetChanged();
myEditText.setText("");
}
});
}

11. Run your application.
You should get something
like:

12. If you have problems check code on github:
(check out, if you are not sure about Github)
Or text me if you found any mistakes or you
want to add something to presentation: