Lecture 5

Lecture

• Video of lecture

Readings

• AsyncTask in the Android Reference.
• Documentation on processes and threads.
• Download manager documentation.
• Gson, the Google Json Java Library.
• Read Chapter 6 of the book (we will do the AppEngine part in the next class).
• Supporting multiple screen sizes and orientations.

Review

• Intents.
• Saving preferences (you can also read ahead to files and databases).
• The Android Activity lifecycle.

Code

• Download in background.
• Sleep in background.
• Download Manager (see code samples for Chapter 6 in the book; these are downloadable).
• Handling orientation changes. Note that the best solution is to have two layouts, one in layout and one in layout-land; then also the initial layout is set correctly. See here.
• Otherwise, you need to set the initial layout after reading the orientation. See here and here about reading the orientation. See also above, in the readings.

Homework 2

Due: Wednesday January 30 end of day.

You need to code an application with two activities, as shown here.

The screen of the main activity contains four buttons, and a listview.

The first three buttons have a label; these labels should be initially (for the first run of the app) set to something useful. Up to you! When you press a button 1-3, the label string is inserted at the top of the listview. The listview can scroll, and you should create some contrast / color scheme if you can that makes this obvious. When you press the fourth button, labeled "Other", you are led to the second Activity.

In the second Activity, you can write the label you want to use, and press enter. The label is then inserted at the top of the listview, and the labels of the buttons are updated.

The buttons 1-3 must be labeled with the labels that have been most recently used by the user, without repetition.

This means that you must have a way to store the labels created, and when they were last used; you can for example use the Shared Preferences (see link above in the Review section) for this purpose.

The list should contain the labels from most recently inserted (at the top) to least recently inserted (at the bottom); you can set a limit to the length of the list, if you wish, and it has to be at least 10. You do not need to persist the list from one run of the app to the other.

Optionally, you can let the user choose a color for the button in the second Activity (just offer a set of 4-6 basic colors, you don't need to do a color picker). The color is then used both for the button, and for the list entry.