在Android中将SQLite数据库中的数据检索到ListView（具有TextViews）的障碍：

Question

我想从db检索数据到某些textviews然后将这些textvies放入listview时遇到一些问题，让我解释一下我的数据库中有两列，例如date和head，我想将它们检索到它们的每个textviews中。并将这些textvie放入列表视图中。我知道这对其他人来说可能是一个愚蠢的问题，但是我是该领域的新手。我对SimpleCursorAdapter有所了解，但不知道如何在哪里使用它。可以通过此方法解决。所以请指导我。

我的班级：：我为database.MyArrayAdapter类创建了DBAdapter类。 一个主类称为Head.java。

DBAdapter.java

 public class DBAdapter  {

//EditText mHead;
public static final String KEY_ROWID="_id";
public static final String KEY_DATE="date";
public static final String KEY_HEAD="head";
private static final String TAG="DBAdapter";

private static final String DATABASE_NAME="accounting";
private static final String DATABASE_TABLE="accounts";
private static final int DATABASE_VERSION=1;

private static final String DATABASE_CREATE=
        "create table accounts (_id integer primary key autoincrement," +
        "date datetime not null, head text not null);";

private final Context context;

private DataBaseHelper DBHelper;
private SQLiteDatabase db;

public DBAdapter(Context ctx){
     this.context=ctx;
     DBHelper=new DataBaseHelper(context);
}
private static class DataBaseHelper extends SQLiteOpenHelper {

    DataBaseHelper(Context context){

        super(context,DATABASE_NAME,null,DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        try {
            db.execSQL(DATABASE_CREATE);

        }catch(SQLException e){
            e.printStackTrace();
        }

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub

        Log.w(TAG, "Updrading database from version "+oldVersion+" to "+newVersion+"," +
                "which will destroy all old data");
        db.execSQL("drop table if exists accounts");
        onCreate(db);
    }
      }

public DBAdapter open() throws SQLException{
db=DBHelper.getWritableDatabase();
return this;

       }

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

**//--insert  contact in the database--**
public long insertContact(String date,String head)
    {

ContentValues initialvalue=new ContentValues();
initialvalue.put(KEY_DATE, date);
initialvalue.put(KEY_HEAD, head);
return db.insert(DATABASE_TABLE, null, initialvalue);


    }

     //--delete a particular contact--
     public boolean deleteContact(long rowId){

return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null)>0;

    }

    //--Retrieving all the contacts--
    public Cursor getAllContacts(){
return db.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_DATE,KEY_HEAD}, null,               null, null, null,null);

    }
   //--Retrieve a particular contact--
    public Cursor getContact(long rowId)throws SQLException{
Cursor mCursor=
        db.query(true, DATABASE_TABLE, new String[]        {KEY_ROWID,KEY_DATE,KEY_HEAD},
                KEY_ROWID + "="+ rowId, null, null, null,
                null, null);
if(mCursor != null){
    mCursor.moveToFirst();
}
return mCursor;

     }
     //--update a contact--
    public Boolean updateContact(long rowId,String date,String head){
ContentValues args=new ContentValues();
args.put(KEY_DATE, date);
args.put(KEY_HEAD, head);
return db.update(DATABASE_TABLE, args, KEY_ROWID  + "=" +rowId,null)>0;

    }

}

---

MyArrayAdapter.java

public class MyArrayAdapter extends ArrayAdapter<Object>{

private final Context context;
private final String[] values;

//@SuppressWarnings("unchecked")
public MyArrayAdapter(Context context,String[] values){
    super(context,R.layout.list_things,values);
    this.context=context;
    this.values=values;
}


@Override
public View getView(int position, View convertView, ViewGroup parent) {
    // TODO Auto-generated method stub
    //return super.getView(position, convertView, parent);
    LayoutInflater inflate=(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View rowview=inflate.inflate(R.layout.list_things, parent, false);
    TextView mDate=(TextView)rowview.findViewById(R.id.tvdate);
    TextView mHead=(TextView)rowview.findViewById(R.id.tvhead);
    mDate.setText(values[position]);
    mHead.setText(values[position]);
    return rowview;
}

}

最后我想做所有事情的班主任

头文件

public class Head extends ListActivity {
String date = "";
String head;
TextView display;
EditText headname;
ListView list;
LayoutInflater inflate;
Layout layout;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.head);
    display=(TextView)findViewById(R.id.tvCurrentDate);
    display.setText(date);
    // Intent intent=new Intent();
    DBAdapter db=new DBAdapter(this);
    SimpleCursorAdapter adapter=new SimpleCursorAdapter(Head.this, R.layout.list_things, null, null, null);

    //Cursor cursor=getContentResolver().query("/data/data/com.crypto.ranjit/DBAdapter",
            //new String []{db., selection, selectionArgs, sortOrder)
    Bundle b = getIntent().getExtras();
    if (b != null) {
        date = b.getString("date");

    }

    Button btnSave = (Button) findViewById(R.id.btnSave);
    btnSave.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            // TODO Auto-generated method stub

            headname=(EditText)findViewById(R.id.etHeadname);
            date=display.getText().toString();

            head=headname.getText().toString();

            DBAdapter dba = new DBAdapter(Head.this);
            dba.open();
            long id = dba.insertContact(date, head);
            // id=dba.insertContact(head, date);

            dba.close();

        }
    });
    //DBAdapter db=new DBAdapter(Head.this);
    //db.open();

}

}

Answer 1

这里有些愚蠢的错误使我感到困惑。

解决方案：1：通过Head.java中定义的静态值填充文本视图。 2：使用ArrayList <HashMap <String，String>>检索数据并填写适配器类。