Android tutorials8 todo_list
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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.
Android tutorials8 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: