Android: I have to display content from the database in the listview, in which latest data comes on top

问题

I have to implement a listview in which my current data comes on top of the listview. Right now my recent data comes at the bottom and my first data is coming on the top of the listview. I'm attaching my work so far:

SearchActivity.java

public class SearchActivity extends Activity implements OnClickListener,
    OnItemClickListener {

private EditText mHistoryNameEditText;
private Button mInsertButton;
private ListView mHistoryListView;

private ListAdapter mHistoryListAdapter;

private ArrayList<SearchHistoryDetails> searchArrayList;

private ArrayList<SearchHistoryDetails> HistoryObjArrayList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mHistoryNameEditText = (EditText) findViewById(R.id.editText1);
    mInsertButton = (Button) findViewById(R.id.button1);
    mInsertButton.setOnClickListener(this);

    mHistoryListView = (ListView) findViewById(R.id.names_lsitviews);
    mHistoryListView.setOnItemClickListener(this);

    searchArrayList = new ArrayList<SearchHistoryDetails>();

    mHistoryListAdapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, populateList());

    mHistoryListView.setAdapter(mHistoryListAdapter);

    HistoryObjArrayList = new ArrayList<SearchHistoryDetails>();
}

@Override
public void onClick(View v) {
    if (v.getId() == R.id.button1) {
        String providedUgraduateName = mHistoryNameEditText.getText()
                .toString();

        SearchHistoryDetails undergraduateDetailsPojoObj = new SearchHistoryDetails();
        undergraduateDetailsPojoObj.setuGraduateName(providedUgraduateName);

        HistoryObjArrayList.add(undergraduateDetailsPojoObj);

        insertUndergraduate(undergraduateDetailsPojoObj);

        finish();
    }
}

public void insertUndergraduate(
        SearchHistoryDetails paraUndergraduateDetailsPojoObj) {

    AndroidOpenDbHelper androidOpenDbHelperObj = new AndroidOpenDbHelper(
            this);

    SQLiteDatabase sqliteDatabase = androidOpenDbHelperObj
            .getWritableDatabase();

    ContentValues contentValues = new ContentValues();

    contentValues.put(AndroidOpenDbHelper.COLUMN_NAME_UNDERGRADUATE_NAME,
            paraUndergraduateDetailsPojoObj.getuGraduateName());
    long affectedColumnId = sqliteDatabase.insert(
            AndroidOpenDbHelper.TABLE_NAME_GPA, null, contentValues);

    sqliteDatabase.close();
    Toast.makeText(this,
            "Values inserted column ID is :" + affectedColumnId,
            Toast.LENGTH_SHORT).show();

}

public List<String> populateList() {

    List<String> uGraduateNamesList = new ArrayList<String>();

    AndroidOpenDbHelper openHelperClass = new AndroidOpenDbHelper(this);

    SQLiteDatabase sqliteDatabase = openHelperClass.getReadableDatabase();

    Cursor cursor = sqliteDatabase.query(
            AndroidOpenDbHelper.TABLE_NAME_GPA, null, null, null, null,
            null, null);

    startManagingCursor(cursor);

    while (cursor.moveToNext()) {

        String ugName = cursor
                .getString(cursor
                        .getColumnIndex(AndroidOpenDbHelper.COLUMN_NAME_UNDERGRADUATE_NAME));

        SearchHistoryDetails ugPojoClass = new SearchHistoryDetails();
        ugPojoClass.setuGraduateName(ugName);

        searchArrayList.add(ugPojoClass);

        uGraduateNamesList.add(ugName);
    }

    sqliteDatabase.close();

    return uGraduateNamesList;
}

@Override
protected void onResume() {
    super.onResume();
    searchArrayList = new ArrayList<SearchHistoryDetails>();
    mHistoryListAdapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, populateList());
    mHistoryListView.setAdapter(mHistoryListAdapter);
}

@Override
protected void onStart() {
    super.onStart();
    searchArrayList = new ArrayList<SearchHistoryDetails>();
    mHistoryListAdapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, populateList());
    mHistoryListView.setAdapter(mHistoryListAdapter);
}

@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {

    Toast.makeText(getApplicationContext(), "Clicked on :" + arg2,
            Toast.LENGTH_SHORT).show();

    SearchHistoryDetails clickedObject = searchArrayList.get(arg2);

    Bundle dataBundle = new Bundle();
    dataBundle.putString("clickedUgraduateName",
            clickedObject.getuGraduateName());
}}

This class helps me in getting the data from the database and populating it on the activity. My creating database class:

AndroidOpenDbHelper.java

public class AndroidOpenDbHelper extends SQLiteOpenHelper {

public static final String DB_NAME = "allsearch_history_db";
public static final int DB_VERSION = 1;

public static final String TABLE_NAME_GPA = "search_table";
public static final String COLUMN_NAME_UNDERGRADUATE_NAME = "undergraduate_name_column";

public AndroidOpenDbHelper(Context context) {
    super(context, DB_NAME, null, DB_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {

    String sqlQueryToCreateUndergraduateDetailsTable = "create table if not exists "
            + TABLE_NAME_GPA
            + " ( "
            + BaseColumns._ID
            + " integer primary key autoincrement, "
            + COLUMN_NAME_UNDERGRADUATE_NAME
            + " text not null); ";

    db.execSQL(sqlQueryToCreateUndergraduateDetailsTable);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    if (oldVersion == 1 && newVersion == 2) {
        // Upgrade the database
    }
}}

This is the class from which I create database and table.

Now, the real deal is that, when I try to populate data from the database it comes as the first one on top and the latest one on down. I want to revert it. Any help will be appreciated in overcoming this problem.

回答1:

There are a few different ways to do this. I recommend using the ORDER BY clause of your query:

Cursor cursor = sqliteDatabase.query(
        AndroidOpenDbHelper.TABLE_NAME_GPA, null, null, null, null, null, 
        AndroidOpenDbHelper.COLUMN_NAME_UNDERGRADUATE_NAME + " DESC");

---

Also if you are only going to read from one column, your query should only request that column. Otherwise you are wasting resources querying unused columns of information:

Cursor cursor = sqliteDatabase.query(
        AndroidOpenDbHelper.TABLE_NAME_GPA,
        new String[] {AndroidOpenDbHelper.COLUMN_NAME_UNDERGRADUATE_NAME},
        null, null, null, null, 
        AndroidOpenDbHelper.COLUMN_NAME_UNDERGRADUATE_NAME + " DESC");

Lastly, you may want to look into using a SimpleCursorAdapter which allows you to bind a query to a ListView with minimal code.

---

Addition I took a closer look at your code and try this:

Cursor cursor = sqliteDatabase.query(
        AndroidOpenDbHelper.TABLE_NAME_GPA, null, null, null, null, null, 
        BaseColumns._ID + " DESC");

回答2:

Well i can suggest you to get the data from the database and add the items in the reverse order in the adapter that you are setting for populating the listview. Consider this as the sample where you can get the values from the database which returns an arraylist. Now consider this arraylist and add each item to the arrayadapter from the last like :

for(i=arraylist.size()-1;i>0;i--)
{ 
   adapter.add(arraylist.get(i));
}

and after setting for the first time you can call

adapter.notifyDataSetChanged() 

to refresh the list automatically. Give a try to this

来源：https://stackoverflow.com/questions/12392501/android-i-have-to-display-content-from-the-database-in-the-listview-in-which-l