使用 SQLite 中的 BaseAdapter 不顯示數據

Question

我試圖使用 baseadapter 顯示來自 sqlite 的數據，但是當我運行我的代碼時。 列表視圖中沒有顯示。 不知道我的代碼有什么問題。 需要你們的幫助，我只是編程初學者。 我將在下面發布我的代碼。

主活動.java

    public class MainActivity extends Activity {

        DatabaseHelper db;
        DoctorListAdapter adapter;
        Context context = MainActivity.this;


        List<Doctor> doctor = new ArrayList<Doctor>();

        ListView l1;

        int startIndex = 0;
        private static final int DISPLAY_LIMIT = 20;

        public MainActivity() {
        }

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

            db = new DatabaseHelper(getApplication());


            l1 = (ListView) findViewById(R.id.listView);
            l1.setAdapter(new DoctorListAdapter(context,doctor ));
            // set data
        }
    }

> DoctorListAdapter.java

public class DoctorListAdapter extends BaseAdapter {

    private Context context;
    private List<Doctor> doctorData = new ArrayList<Doctor>();

    public DoctorListAdapter(Context context, List<Doctor> doctorData){
        this.context = context;
        this.doctorData = doctorData;

    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return doctorData.size();
    }

    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return doctorData.get(position);
    }

    @Override
    public long getItemId(int positionId) {
        // TODO Auto-generated method stub
        return positionId;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        ViewHolder holder;
        Doctor doctor = doctorData.get(position);

        if(convertView == null){

            LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.item_doctor, parent, false);

            holder = new ViewHolder();
            holder.doctorlist_image = (ImageView)convertView.findViewById(R.id.doctorlist_image);
            holder.doctorlist_name = (TextView)convertView.findViewById(R.id.doctorlist_name);
            holder.doctorlist_id = (TextView)convertView.findViewById(R.id.doctorlist_id);
            holder.doctorlist_gender = (TextView)convertView.findViewById(R.id.doctorlist_gender);

            convertView.setTag(holder);

        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        return convertView;
    }

    static class ViewHolder{

        ImageView doctorlist_image;
        TextView doctorlist_name,
                doctorlist_gender,
                doctorlist_id;
    }


}

醫生.java

public class Doctor implements Serializable {

    private int doctorId;
    private String fullName;
    private String gender;

    public Doctor(){

    }

    public Doctor(int doctorId,
                  String gender,
                  String fullName){

        this.doctorId = doctorId;
        this.gender = gender;
        this.fullName = fullName;

    }


    public int getDoctorId() {
        return doctorId;
    }

    public void setDoctorId(int doctorId) {
        this.doctorId = doctorId;
    }

    public String getFullName() {
        return fullName;
    }

    public void setFullName(String fullName) {
        this.fullName = fullName;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

}

數據庫助手類

public class DatabaseHelper extends SQLiteOpenHelper {

    private static final String DB_PATH = "/data/data/com.example.jathniel.myapplication/databases/";
    private static final String DB_NAME = "mydoctorfinder_new_migrate.sqlite";
    private SQLiteDatabase myDataBase;
    private Context myContext = null;

    private static final String TABLE_DOCTOR = "doctors";

    final static String KEY_ID = "id",
            KEY_FULLNAME = "full_name",
            KEY_GENDER = "gender";


    public DatabaseHelper(Context context) {
        super(context, DB_NAME, (SQLiteDatabase.CursorFactory) null, 1);
        this.myContext = context;
    }

    public void createDataBase() throws IOException {
        boolean dbExist = this.checkDataBase();
        if(!dbExist) {
            this.getReadableDatabase();

            try {
                this.copyDataBase();
            } catch (IOException e) {
                throw new Error("Error");
            }
        }
    }

    public void copyDataBase() throws IOException {
        InputStream myInput = this.myContext.getAssets().open(DB_NAME);
        String outFileName = DB_PATH + DB_NAME;
        FileOutputStream myOutput = new FileOutputStream(outFileName);
        byte[] buffer = new byte[1024];

        int length;
        while((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }

        myOutput.flush();
        myOutput.close();
        myInput.close();
    }

    public boolean checkDataBase() {
        SQLiteDatabase checkDB = null;

        try {
            String e = DB_PATH + DB_NAME;
            checkDB = SQLiteDatabase.openDatabase(e, (SQLiteDatabase.CursorFactory)null, 0);
        } catch (SQLiteException e) {
            ;
        }

        if(checkDB != null) {
            checkDB.close();
        }

        return checkDB != null;
    }

    public void openDataBase() throws SQLException {
        String myPath = DB_PATH + DB_NAME;
        this.myDataBase = SQLiteDatabase.openDatabase(myPath, (SQLiteDatabase.CursorFactory)null, 0);
    }

    public synchronized void close() {
        if(this.myDataBase != null) {
            this.myDataBase.close();
        }

        super.close();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

    }

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

    public void createDatabase() {
    }

    private Doctor getDoctor(int doctor_id){
        Doctor doctor = new Doctor();
        String selectQuery = "SELECT  * FROM " + TABLE_DOCTOR + " WHERE id = "+doctor_id;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor c = db.rawQuery(selectQuery, null);
        if (c.moveToFirst()) {
            //System.out.println("KEY_FIRSTNAME: "+c.getString(c.getColumnIndex(KEY_FIRSTNAME)));
            doctor.setDoctorId(c.getInt(c.getColumnIndex(KEY_ID)));
            doctor.setGender(c.getString(c.getColumnIndex(KEY_GENDER)));
            doctor.setFullName(c.getString(c.getColumnIndex(KEY_FULLNAME)));
        }
        c.close();
        return doctor;
    }

    public List<Doctor> getAllDoctor(int start) {
        //@http://www.androidhive.info/2013/09/android-sqlite-database-with-multiple-tables/
        final int maxCount = 20;
        List<Doctor> doctorList = new ArrayList<Doctor>();
        String selectQuery = "SELECT  * FROM " + TABLE_DOCTOR + " LIMIT "+maxCount+" OFFSET "+start;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor c = db.rawQuery(selectQuery, null);
        // looping through all rows and adding to list
        if (c.moveToFirst()) {
            do {
                Doctor doctor = new Doctor();
                doctor.setDoctorId(c.getInt(c.getColumnIndex(KEY_ID)));
                doctor.setGender(c.getString(c.getColumnIndex(KEY_GENDER)));
                doctor.setFullName(c.getString(c.getColumnIndex(KEY_FULLNAME)));
                doctorList.add(doctor);
            } while (c.moveToNext());
        }
        c.close();
        return doctorList;
    }

}

Answer 1

在 getView() 中添加以下命令

     holder=(ViewHolder) convertView.getTag();

            holder.doctorlist_name.setText("my_title");