Question

我在MyDBHandler类中有两个方法，一个用于添加详细信息，另一个用于更新详细信息。用户填写表单并将其详细信息添加到数据库中并作为listView输出。我希望用户能够再次填写相同的表单来更新他们的详细信息。我的问题是，当我第一次安装应用程序时，没有更新的记录，所以我必须使用addDetails方法，当我想要做的是使用updateDetails方法更新细节时，不断向数据库添加新行。如果首次安装应用程序时无法更新，我无法更新详细信息。

addDetails方法

//Add a new row to the database
public void addDetails(Details details) {
    ContentValues values = new ContentValues();

    values.put(COLUMN_FIRSTNAME, details.getFirstname());
    values.put(COLUMN_SURNAME, details.getSurname());
    values.put(COLUMN_PHONE, details.getPhone());
    values.put(COLUMN_EMAIL, details.getEmail());
    values.put(COLUMN_ADDRESS1, details.getAddress1());
    values.put(COLUMN_ADDRESS2, details.getAddress2());

    SQLiteDatabase db = getWritableDatabase();
    db.insert(TABLE_DETAILS, null, values);
    db.close();
}

updateDetails方法

//Updates user details
public void updateDetails(Details details){
    ContentValues values = new ContentValues();

    //Take new values from the details object provided
    values.put(COLUMN_FIRSTNAME, details.getFirstname());
    values.put(COLUMN_SURNAME, details.getSurname());
    values.put(COLUMN_PHONE, details.getPhone());
    values.put(COLUMN_EMAIL, details.getEmail());
    values.put(COLUMN_ADDRESS1, details.getAddress1());
    values.put(COLUMN_ADDRESS2, details.getAddress2());

    SQLiteDatabase db = this.getWritableDatabase();

    //Update the details object where id matches
    db.update(TABLE_DETAILS, values, COLUMN_ID + "='" + details._id + "'", null);


    db.close();

}

FragmentTab1类

import com.astuetz.viewpager.extensions.sample.*;

import android.database.Cursor;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.view.View.OnClickListener;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import android.widget.Toast;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;


public class FragmentTab1 extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment1, container, false);
    super.onCreate(savedInstanceState);





    //setContentView(R.layout.fragment1);
    firstName = (TextView) rootView.findViewById(R.id.firstName);
    editTextName = (EditText) rootView.findViewById(R.id.editTextName);
    textView5 = (TextView) rootView.findViewById(R.id.surName);
    editTextSurname = (EditText) rootView.findViewById(R.id.editTextSurname);
    textView4 = (TextView) rootView.findViewById(R.id.mobile);
    editTextMobile = (EditText) rootView.findViewById(R.id.editTextMobile);
    textView2 = (TextView) rootView.findViewById(R.id.Email);
    editTextEmail = (EditText) rootView.findViewById(R.id.editTextEmail);
    textView3 = (TextView) rootView.findViewById(R.id.address1);
    editTextAddress1 = (EditText) rootView.findViewById(R.id.editTextAddress1);
    textView6 = (TextView) rootView.findViewById(R.id.address2);
    editTextAddress2 = (EditText) rootView.findViewById(R.id.editTextAddress2);

    dbHandler = new MyDBHandler(getActivity(), null, null, 1);



    Button addButtonClicked = (Button)rootView.findViewById(R.id.addButtonClicked);
    addButtonClicked.setOnClickListener(new OnClickListener(){
        public void onClick(View v)
        {
            addButtonClicked(v);
        }
    });

    return rootView;
}



TextView firstName;
EditText editTextName;

TextView textView5;
EditText editTextSurname;

TextView textView4;
EditText editTextMobile;

TextView textView2;
EditText editTextEmail;

TextView textView3;
EditText editTextAddress1;

TextView textView6;
EditText editTextAddress2;

MyDBHandler dbHandler;



//validate email provided by user
private boolean isValidEmail(String email) {
    String EMAIL_PATTERN = "^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@"
            + "[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$";

    Pattern pattern = Pattern.compile(EMAIL_PATTERN);
    Matcher matcher = pattern.matcher(email);
    return matcher.matches();
}



//Add details to the database and shared preferences
public void addButtonClicked(View view) {



    final String email = editTextEmail.getText().toString();
    if (!isValidEmail(email))
    {
        editTextEmail.setError("Invalid Email");
        Toast.makeText(getActivity().getApplicationContext(), "Invalid email format",
                Toast.LENGTH_LONG).show();

    }
    else if( editTextName.getText().toString().length() == 0 )
    {
        editTextName.setError("First name is required!");
        Toast.makeText(getActivity().getApplicationContext(), "First name is required",
                Toast.LENGTH_LONG).show();
    }
    else if( editTextSurname.getText().toString().length() == 0 )
    {
        editTextSurname.setError("Surname is required!");
        Toast.makeText(getActivity().getApplicationContext(), "Surname is required",
                Toast.LENGTH_LONG).show();
    }
    else if( editTextMobile.getText().toString().length() == 0 || editTextMobile.getText().toString().length() < 10 )
    {
        editTextMobile.setError("Not a valid number!");
        Toast.makeText(getActivity().getApplicationContext(), "Not a valid number",
                Toast.LENGTH_LONG).show();
    }
    else if( editTextAddress1.getText().toString().length() == 0 )
    {
        editTextAddress1.setError("Address Line 1 is required!");
        Toast.makeText(getActivity().getApplicationContext(), "Address Line 1 is required",
                Toast.LENGTH_LONG).show();
    }
    else if( editTextAddress2.getText().toString().length() == 0 )
    {
        editTextAddress2.setError("Address Line 2 is required!");
        Toast.makeText(getActivity().getApplicationContext(), "Address Line 2 is required",
                Toast.LENGTH_LONG).show();
    }
    else
    {
        Details details = new Details();
        details.set_id(1);
        details.setFirstname(editTextName.getText().toString());
        details.setSurname(editTextSurname.getText().toString());
        details.setPhone(editTextMobile.getText().toString());
        details.setEmail(editTextEmail.getText().toString());
        details.setAddress1(editTextAddress1.getText().toString());
        details.setAddress2(editTextAddress2.getText().toString());
        dbHandler.addDetails(details);
        Toast.makeText(getActivity().getApplicationContext(), "Details saved successfully",
                Toast.LENGTH_LONG).show();
    }

}

}

Answer 1

你必须检查表是否为空，为此，在'MyDBHandler'中创建一个名为'Exists'的方法：

 public boolean Exists {

   SQLiteDatabase db = this.getWritableDatabase();

   String Query = "SELECT * FROM TABLE_DETAILS " ;

   Cursor cursor = db.rawQuery(Query,null);
    if(cursor.moveToFirst()){
        Log.i("CHECK", "true");
        return true;
    }
    return false;

}

然后在您的活动通话中存在类似的内容：

 MyDBHandler db;
 db = new MyDBHandler(getApplicationContext());
 db.getWritableDatabase();

            if ((db.Exists( ))) {
                Toast.makeText(getApplicationContext(), "Please add first your Details", Toast.LENGTH_SHORT).show();

            }else{
            //update your Database
  }

希望这有帮助

添加和更新SQLite数据库的详细信息

1 个答案: