Question

我从Listview中的数据库中获取数据。我需要在用户点击它时删除此行。我通过从Stackoverflow参考来尝试它，似乎一切正常但数据库没有更新。请帮忙!!!

这是我的DatabaseAdapter1.java的代码

package com.example.utkarsh.stopwatch;

import android.content.ContentValues;
import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;


public class DatabaseAdapter1 {

DatabaseHelper1 helper;

public DatabaseAdapter1(Context context)
{
    helper = new DatabaseHelper1(context);
}




static class DatabaseHelper1 extends SQLiteOpenHelper
{
    private static final String DATABASE_NAME = "db_database1.db";
    private static final int DATABASE_VERSION = 1;
    public static final String TABLE_NAME = "db_table11";
    public static final String UID = "_id";
    public static final String TIMESTR = "timeInStr";
    private static final String DROP_TABLE = "DROP TABLE IF EXISTS " + TABLE_NAME;

    private static final String TABLE_CREATE =
            "CREATE TABLE " + TABLE_NAME + " (" +
                    UID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                    TIMESTR + " VARCHAR(255) " +
                    ");";

    private Context context;

    public DatabaseHelper1(Context context)
    {
        super(context , DATABASE_NAME , null , DATABASE_VERSION);
        this.context = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

        try {
            Log.v("qwerty" , "before onCreate");
            db.execSQL(TABLE_CREATE);
            Log.v("qwerty" , "after onCreate");
        } catch (SQLException e) {
            Log.v("qwerty" , "onCreate Error \n" + e);
        }
    }

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

        db.execSQL(DROP_TABLE);
        onCreate(db);
    }

}


public long insertData(String  timeInMS)
{
    SQLiteDatabase db = helper.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(DatabaseHelper1.TIMESTR, timeInMS );
    long id = db.insert(DatabaseHelper1.TABLE_NAME , null , contentValues);
    return id;
}

}

这是我的ShowAllTime.java的代码

package com.example.utkarsh.stopwatch;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.Toast;

/**
 * Created by utkarsh on 6/4/15.
 */
public class ShowAllTime extends Activity {


DatabaseAdapter1.DatabaseHelper1 dbHelper1;
DatabaseAdapter.DatabaseHelper dbHelper;
SQLiteDatabase db;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.list_all);



  openDB();
    populateDB();
    registerListClickCallbacks();

}




private void openDB() {

    dbHelper1 = new DatabaseAdapter1.DatabaseHelper1(this);
    db = dbHelper1.getWritableDatabase();

}

private void populateDB() {

    String [] column = {DatabaseAdapter1.DatabaseHelper1.UID , DatabaseAdapter1.DatabaseHelper1.TIMESTR};
    Cursor cursor = db.query(DatabaseAdapter1.DatabaseHelper1.TABLE_NAME, column, null, null, null, null, DatabaseAdapter1.DatabaseHelper1.UID + " DESC");


    startManagingCursor(cursor);

    //setup mapping from cursor
    String [] fromFieldNames = new String []
            {DatabaseAdapter1.DatabaseHelper1.TIMESTR };

    int [] toViewIds = new int[]
            {R.id.itemLayout_textView };


    //create adapter to map columns
    SimpleCursorAdapter myCursorAdapter = new SimpleCursorAdapter(
            this,
            R.layout.item_layout,
            cursor,
            fromFieldNames,
            toViewIds
    );

    //set my adapter to list view
    ListView myList = (ListView) findViewById(R.id.listView);
    myList.setAdapter(myCursorAdapter);
}

private void registerListClickCallbacks() {

    final ListView myList = (ListView) findViewById(R.id.listView);
    myList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View viewClicked, final int position, long idInDB) {


            AlertDialog.Builder ab;
            ab = new AlertDialog.Builder(ShowAllTime.this);
            ab.setIcon(android.R.drawable.ic_dialog_alert)
                    .setTitle("Closing App")
                    .setMessage("Do you really wanna delete?")
                    .setPositiveButton("Yes", new DialogInterface.OnClickListener()
                    {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            Toast.makeText(ShowAllTime.this, "DELETE THIS SHIT at pos " + position  ,Toast.LENGTH_LONG).show();
                            SQLiteDatabase db = dbHelper1.getWritableDatabase();
                            db.delete(DatabaseAdapter1.DatabaseHelper1.TABLE_NAME, DatabaseAdapter1.DatabaseHelper1.UID + "=" +position,null);
                            populateDB();
                        }

                    })
                    .setNegativeButton("No", null)
                    .show();

        }
    });

}

}


//reference taken from
//https://www.youtube.com/watch?v=gaOsl2TtMHs

Answer 1

请试试这个：

 db.delete(DatabaseAdapter1.DatabaseHelper1.TABLE_NAME, DatabaseAdapter1.DatabaseHelper1.UID + "=?", new String[] { String.valueOf(position) });

Answer 2

我这样做的一种方法是使用删除和更新方法：

public void deleteCredit(long id) {
    SQLiteDatabase database = this.getReadableDatabase();
    String deleteQuery = "DELETE FROM " + Constants.CREDIT_TABLE_NAME + " WHERE id =" + id;
    database.execSQL(deleteQuery);      
}

然后是更新方法：

 public boolean postCreditDeleteUpdate(String creditorId, double amountOwed) {

    SQLiteDatabase database = this.getWritableDatabase();
    String filter = Constants.CREDITOR_TABLE_ID +"= '" +creditorId +"'";
    ContentValues contentValues = new ContentValues();

    int newTotalCredits = getCreditor(creditorId).getTotalCredits() - 1;
    double newAmountOwed = getCreditor(creditorId).getTotalAmountOwed() - amountOwed;

    contentValues.put(Constants.CREDITOR_TABLE_TOTAL_CREDITS, newTotalCredits);
    contentValues.put(Constants.CREDITOR_TABLE_TOTAL_AMOUNT_OWED, newAmountOwed);

    return database.update(Constants.CREDITOR_TABLE_NAME, contentValues, filter, null) > 0;

}

我现在在我的Fragment（或Activity）中调用此代码，如下所示：

     DatabaseManager databaseManager;
     ...
     databaseManager.deleteCredit(creditId);
 databaseManager.postCreditDeleteUpdate(creditorPhone, amountOwed);

我希望你明白这个想法？

无法通过单击从Database-ListView中删除

2 个答案: