Android: In which way should I separate code from

问题:

Beginning Android programming, coming from html/php/css, I have searched the web for a simple way to separate my code from my style - for now I need to display data from a database in a list- or table view.

Simply put, I get a cursor from the database, iterate through it, creating each list-item dynamically in code as TextViews. Then I would like to apply a style from an external xml layout file to each item.

Pseudo-code:

style.xml:

//mystyle: bold, 12pt

//yourstyle: italic, 11pt

Activity:

for (each cursor-entry)
{
  tv1 = new TextView();
  applyStyle(tv, mystyle);

  tv2 = new TextView();
  applyStyle(tv, yourstyle);

  //Apply content to textviews from the cursor...
}
mainLayout.setView(tv1);
mainLayout.setView(tv2);

The code examples I've found around the net, uses multiple lines of code, or multiple xml files (using inflate, or cursorAdapters), and IMO quickly become bloated. I just want a nice neat way to apply a style to a dynamically created code. Is this possible?

回答1:

If you are using ListView, it is so simple to have an XML file for rows. The only thing you need is an XML file and a Adapter class. Take a look at this simple example:

To read data from database, create a helper class like this:

public class MessagingDatabaseAdapter {
    protected SQLiteDatabase database;  

    public MessagingDatabaseAdapter(Context context) {
        MessagingDatabaseHelper databaseHelper = new MessagingDatabaseHelper(context, "message_history_db");
        database = databaseHelper.getWritableDatabase();        
    }

    public void close() {
         database.close();
    }

    public void Entity[] getAllEntities() {
        Entity[] values = null;
        String query = "select * from TABLE_NAME";
        Cursor cursor = null;
        try {
            cursor = database.rawQuery(query, null);
            if( cursor.moveToFirst() ) {
                int s = cursor.getCount();
                values = new Entity[s];
                do {
                    Entity entity = new Entity();
                    entity.setSomeProperty(cursor.getInt(cursor.getColumnIndex(SOME_PROPERTY_COLUMN)));
                    values[i++] = entity;
                } while( cursor.moveToNext() ); 
            }
        } catch(Exception ex) {
        } finally {
            if( cursor != null ) {
                cursor.close();
            }               
            return values;
        }
    }

    protected class MessagingDatabaseHelper extends SQLiteOpenHelper {

        public MessagingDatabaseHelper(Context context, String name) {
            super(context, name, null, 1);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
        db.execSQL("Your SQL to create Tables");
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        }
    }
}

In your Activity class:

MessagingDatabaseAdapter db = new MessagingDatabaseAdapter();
values = db.getAllEntities();
db.close();

list_view = (ListView) findViewById(R.id.list_view);
ListAdapter adapter = new ListAdapter(this, values); 
list_view.setAdapter(adapter);

And ListAdapter class:

public class ListAdapter extends ArrayAdapter<Entity> {
    final Context context;
    final Entity[] values;      

    public ListAdapter(Context context, Entity[] values) {
        super(context, R.layout.list_screen, values);
        this.values = values;
        this.context = context;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View rowView = inflater.inflate(R.layout.list_view_item, parent, false);

        TextView datetimeTextView = (TextView) rowView.findViewById(R.id.list_view_datetime_text_view);
        datetimeTextView.setTypeface(someTypeFace);
        return rowView;
    }       
}   

And row layout XML file (list_view_item.xml):

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    style="@style/BorderedFrame" >

    <TextView
        android:id="@+id/inbox_list_view_datetime_text_view"
        style="@style/MediumText"
        android:layout_width="wrap_content" >
    </TextView>

</RelativeLayout>