android - 删除android sqlite表中的一行

Question

我想删除数据库表中的一行我使用的是 ListView ，在长按列表项后，您将看到显示编辑和删除方法的警告对话框当我单击编辑方法时，模拟器运行正常，但是当我单击删除方法时，会出现强制关闭通知。我是 Android 编程的新手，你能解释一下我的代码有什么问题吗这是我的代码对于数据库助手:

import android.content.Context;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase;

class PuraHelper extends SQLiteOpenHelper {

private SQLiteDatabase db;
public final String TABLE_NAME = "pura";
public final String TABLE_ROW_ID = "_id";
public final String NAMA_PURA = "nama_pura";
public final String KABUPATEN = "kabupaten";
public final String JALAN = "jalan";
public final String LONGITUDE = "longitude";
public final String LATITUDE = "latitude";
public final String KETERANGAN = "keterangan";

private static final String DATABASE_NAME="PPB.db";
private static final int SCHEMA_VERSION=1;

public PuraHelper(Context context) {
    super(context, DATABASE_NAME, null, SCHEMA_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
    String CreateTablePura="create table"+TABLE_ROW_ID+"INTEGER PRIMARY KEY AUTOINCREMENT,"+ NAMA_PURA + "TEXT," + KABUPATEN + "TEXT,"+ JALAN + "TEXT," +LONGITUDE + "TEXT," + LATITUDE + "TEXT," + KETERANGAN + "TEXT";
    db.execSQL(CreateTablePura);

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // no-op, since will not be called until 2nd schema
    // version exists
}

public Cursor getAll() {
    String SelectAll = "SELECT _id, nama_pura, kabupaten, jalan, longitude, latitude, keterangan FROM pura ORDER BY nama_pura";
    return(getReadableDatabase()
                    .rawQuery(SelectAll,
                            null));
}

public Cursor getById(String id) {
    String SelectById = "SELECT _id, nama_pura, kabupaten, jalan, longitude, latitude, keterangan FROM pura WHERE _ID=?";
    String[] args={id};
    return(getReadableDatabase()
                    .rawQuery(SelectById, args));
}

public void insert(String nama_pura, String kabupaten, String jalan, String longitude, String latitude, String keterangan) {
    ContentValues cv=new ContentValues();

    cv.put("nama_pura", nama_pura);
    cv.put("kabupaten", kabupaten);
    cv.put("jalan", jalan);
    cv.put("longitude", longitude);
    cv.put("latitude", latitude);
    cv.put("keterangan", keterangan);
    getWritableDatabase().insert("pura", "nama", cv);
}

public void update(String id, String nama_pura, String kabupaten, String jalan, String longitude, String latitude, String keterangan) {
    ContentValues cv=new ContentValues();
    String[] args={id};

    cv.put("nama_pura", nama_pura);
    cv.put("kabupaten", kabupaten);
    cv.put("jalan", jalan);
    cv.put("longitude", longitude);
    cv.put("latitude", latitude);
    cv.put("keterangan", keterangan);
    getWritableDatabase().update("pura", cv, "_ID=?", args);
}

public void deleteRow(long rowId)
{
    // ask the database manager to delete the row of given id
    //db.delete(TABLE_NAME, TABLE_ROW_ID + "=" + rowId, null);

    db.delete(TABLE_NAME, TABLE_ROW_ID + "="+rowId,null);

}


public String getId(Cursor c) {
    return(c.getString(0));
}
public String getNama(Cursor c) {
    return(c.getString(1));
}
public String getKab(Cursor c) {
    return(c.getString(2));
}
public String getJalan(Cursor c) {
    return(c.getString(3));
}
public String getLong(Cursor c) {
    return(c.getString(4));
}
public String getLat(Cursor c) {
    return(c.getString(5));
}
public String getKet(Cursor c) {
    return(c.getString(6));
}

对于我的 java 类:

import android.app.AlertDialog;
import android.app.ListActivity;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.CursorAdapter;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.AdapterView.OnItemLongClickListener;

public class db_list extends ListActivity {

protected static final String ID_EXTRA = "com.jigler.ppb._ID";
PuraHelper helper=null;
Cursor model=null;
PuraAdapter adapter=null;

EditText    etNama, etKabupaten,etJalan, etLong, etLat, etKeterangan;
Button      bSave, bCancel;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.tab_list);

    helper=new PuraHelper(this);

    etNama = (EditText)findViewById(R.id.etNama);
    etKabupaten = (EditText)findViewById(R.id.etKabupaten);
    etJalan = (EditText)findViewById(R.id.etJalan);
    etLong = (EditText)findViewById(R.id.etLong);
    etLat = (EditText)findViewById(R.id.etLat);
    etKeterangan = (EditText)findViewById(R.id.etKeterangan);

    model=helper.getAll();
    startManagingCursor(model);
    adapter=new PuraAdapter(model);
    setListAdapter(adapter);

     ListView lv = getListView();
     lv.setLongClickable(true);
     lv.setOnItemLongClickListener(new OnItemLongClickListener() {

        public boolean onItemLongClick(AdapterView<?> list, View view,
                int position, long id) {
            // TODO Auto-generated method stub
            alert_editlist(id);
            return true;
        }           
     });
}

@Override
public void onDestroy() {
    super.onDestroy();
    helper.close();
}

@Override
public void onListItemClick(ListView list, View view, int position, long id) {
    Intent i=new Intent(db_list.this, db_new_man.class);

    i.putExtra(ID_EXTRA, String.valueOf(id));
    startActivity(i);
}

private void alert_editlist(final long id) {
    // TODO Auto-generated method stub
    final CharSequence[] items = {"Edit", "Delete"};

    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("What do you want to do?");
    builder.setIcon(R.drawable.ic_setting_36);
    builder.setSingleChoiceItems(items, -1, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int item) {

            if (items[item]=="Edit") {
                Intent i=new Intent(db_list.this, db_new_man.class);
                i.putExtra(ID_EXTRA, String.valueOf(id));
                startActivity(i);
            }
            else if(items[item]=="Delete"){
                                    //this is where my app force close
                helper.deleteRow(id);
                model.requery();
            }
            finish();
        }
    });
    AlertDialog alert = builder.create();
    alert.show();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    new MenuInflater(this).inflate(R.menu.option, menu);
    return(super.onCreateOptionsMenu(menu));
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    if (item.getItemId()==R.id.add) {
        //startActivity(new Intent(db_list.this, db_new.class));
        alert_db_new();
        return(true);
    }
    return(super.onOptionsItemSelected(item));
}

private void alert_db_new() {
    // TODO Auto-generated method stub
    final CharSequence[] items = {"Auto", "Manual"};

    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("Use Your Configuration Setting By");
    builder.setIcon(R.drawable.ic_setting_36);
    builder.setSingleChoiceItems(items, -1, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int item) {

            if (items[item]=="Auto") {
                startActivity(new Intent(db_list.this, db_new_auto.class));
            }
            else if(items[item]=="Manual"){
                startActivity(new Intent(db_list.this, db_new_man.class));
            }
            finish();
        }
    });
    AlertDialog alert = builder.create();
    alert.show();
}



/*
private View.OnClickListener onSave=new View.OnClickListener() {
    public void onClick(View v) {
        helper.insert
        (
                etNama.getText().toString(),
                etKabupaten.getText().toString(),
                etJalan.getText().toString(),
                etLong.getText().toString(),
                etLat.getText().toString(),
                etKeterangan.getText().toString()
        );
        model.requery();

    }
};
*/

class PuraAdapter extends CursorAdapter {
    PuraAdapter(Cursor c) {
        super(db_list.this, c);
    }
    @Override
    public void bindView(View row, Context ctxt, Cursor c) {
        // TODO Auto-generated method stub
        PuraHolder holder=(PuraHolder)row.getTag();

        holder.populateFrom(c, helper);
    }

    @Override
    public View newView(Context ctxt, Cursor c, ViewGroup parent) {
        // TODO Auto-generated method stub
        LayoutInflater inflater=getLayoutInflater();
        View row=inflater.inflate(R.layout.row, parent, false);
        PuraHolder holder=new PuraHolder(row);

        row.setTag(holder);

        return(row);
    }
}
static class PuraHolder {
    private TextView nama=null;
    private TextView alamat=null;
    private ImageView icon=null;

    PuraHolder(View row) {
        nama=(TextView)row.findViewById(R.id.nama_pura);
        alamat=(TextView)row.findViewById(R.id.jalan);
        icon=(ImageView)row.findViewById(R.id.icon_pura);
    }

    void populateFrom(Cursor c, PuraHelper helper) {
        nama.setText(helper.getNama(c));
        alamat.setText(helper.getJalan(c));
        icon.setImageResource(R.id.icon_pura);
    }
}

 }

谢谢关注

Answer 1

我认为您没有在代码中实例化“db”。

使用

getWritableDatabase().delete(TABLE_NAME, TABLE_ROW_ID + "="+rowId,null)

代替

db.delete(TABLE_NAME, TABLE_ROW_ID + "="+rowId,null)

可能会有帮助。