android - SQLite 数据库，已创建表，但未将值插入表中

Question

我正在尝试执行 SQLite 数据库示例，因为该表已成功创建但未插入值。请帮我。

public class MainActivity extends Activity {

String TAG = "MainActivity";
public DatabaseHelperAdapter dbHelper;
protected static final String String = null;
private Button save, cancel;
EditText fname, lname;

public static String FirstName = "";
public static String LastName = "";

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

    save = (Button) findViewById(R.id.btn_save);
    cancel = (Button) findViewById(R.id.btn_cancel);

    fname = (EditText) findViewById(R.id.edit_fname);
    lname = (EditText) findViewById(R.id.edit_lname);

    dbHelper = new DatabaseHelperAdapter(MainActivity.this);
    dbHelper.open();

    save.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            dbHelper.addValues(FirstName, LastName);

        }
    });

}

数据库助手适配器

public class DatabaseHelperAdapter {

private static final String TAG = "DatabaseHelper";
public static final String Id = "_id";
public static final String FIRSTNAME = "first_name";
public static final String LASTNAME = "last_name";

private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
private Context contex;

private static final String DATABASE_NAME = "Aadhaar";
private static final String DATABASE_TABLE = "Enrollment";
private static final int DATABASE_VERSION = 3;


private static final String DATABASE_CREATE = "create table Enrollment (_id integer primary key autoincrement, "
        + "first_name text not null, last_name text not null);";

private static class DatabaseHelper extends SQLiteOpenHelper {

    DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

        db.execSQL(DATABASE_CREATE);

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                + newVersion + ", which will destroy all old data");
        db.execSQL("DROP TABLE IF EXISTS Regist");
        onCreate(db);
    }

}

public DatabaseHelperAdapter(Context contex) {
    super();
    this.contex = contex;
}

public DatabaseHelperAdapter open() throws SQLException {

    mDbHelper = new DatabaseHelper(contex);
    mDb = mDbHelper.getWritableDatabase();
    return this;
}

public long addValues(String fname, String lname) {

    ContentValues initialValues = new ContentValues();

    initialValues.put(FIRSTNAME, fname);
    initialValues.put(LASTNAME, lname);

    return mDb.insert(DATABASE_TABLE, null, initialValues);
}

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

如果我通过 SQLite 编辑器手动输入值，那么值就会成功添加。

Answer 1

在按钮的 onClick 方法中创建 Sqlite 数据库类的对象

save.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
         dbHelper = new DatabaseHelperAdapter(MainActivity.this);
         dbHelper.open();
         dbHelper.addValues(FirstName, LastName);
         dbHelper.close();
    }
});

Answer 2

尝试这个：

       public void addValues(String fname, String Sname){
       //Get a writeable database
       SQLiteDatabase  db = getWritableDatabase();
        //Add your values to the contentValues
        ContentValues values = new ContentValues();
        values.put(Fname, fname);
        values.put(Sname,sname);

        //the table name is the name of your table
        //Insert the information in the contentValues values
        db.insert(table_name, null, values);
        db.close();
    } 

Answer 3

public class MainActivity extends Activity {

String TAG = "MainActivity";
public DatabaseHelperAdapter dbHelper;
protected static final String String = null;
private Button save, cancel;
EditText fname, lname;

public static String FirstName = "";
public static String LastName = "";

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

save = (Button) findViewById(R.id.btn_save);
cancel = (Button) findViewById(R.id.btn_cancel);

fname = (EditText) findViewById(R.id.edit_fname);
lname = (EditText) findViewById(R.id.edit_lname);

dbHelper = new DatabaseHelperAdapter(MainActivity.this);
dbHelper.open();

save.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
//You **Missed** these two lines of code..........

 FirstName=fname.getText().toString();
 LastName=lname.getText().toString();


        dbHelper.addValues(FirstName, LastName);

    }
});

}