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Android tutorials8 todo_list

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Android tutorials8 todo_list

  1. 1. Welcome!
  2. 2. Today we are going to create a new Android Application from scratch.
  3. 3. Create a new Android Project with a name ToDoList If you have problems, look through previous tutorial.
  4. 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. 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. 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. 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. 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. 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. 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. 11. Run your application. You should get something like:
  12. 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:

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