Question

我知道它反复出现的问题，但是没有一种解决方案对我有用。

我是sql数据库的新手。我正在从站点tutorialpoint练习示例。示例Link 我收到.CursorIndexOutOfBoundsException：请求索引0，从数据库中删除名称时出现大小为0的错误。因此，如果我在数据库中添加4个名称，并开始删除第一个名称，它将被删除，然后单击第二个名称，这会给我这个错误（.CursorIndexOutOfBoundsException：请求索引0，大小为0）。然后，如果我单击第三个名称，则可以删除该名称，但第四个名称却有相同的错误。我希望用户可以从数据库中删除任何行，也可以删除整个行

错误

02-22 20:53:59.546 6148-6148/com.xxxx E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.xx.x.Activity}: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
    at android.app.ActivityThread.access$600(ActivityThread.java:123)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4424)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
    at dalvik.system.NativeStart.main(Native Method)
 Caused by: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0
    at android.database.AbstractCursor.checkPosition(AbstractCursor.java:400)
    at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:136)
    at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:50)
    at com.solution.tracking.forklift.DetailsActivity.onCreate(xxxjava:47)
    at android.app.Activity.performCreate(Activity.java:4465)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)

数据库

public class DBHelper extends SQLiteOpenHelper {

public static final String DATABASE_NAME = "MyDBName.db";
public static final String CONTACTS_TABLE_NAME = "contacts";
public static final String CONTACTS_COLUMN_ID = "id";
public static final String CONTACTS_COLUMN_NAME = "name";

private HashMap hp;

public DBHelper(Context context) {
    super(context, DATABASE_NAME , null, 1);
}

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(
            "create table contacts " +
                    "(id integer primary key, name text)"
    );
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS contacts");
    onCreate(db);
}

public boolean insertContact(String name) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put("name", name);

    db.insert("contacts", null, contentValues);
    return true;
}

public Cursor getData(int id) {
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor res =  db.rawQuery( "select * from contacts where id="+id+"", null );
    return res;
}

public int numberOfRows(){
    SQLiteDatabase db = this.getReadableDatabase();
    int numRows = (int) DatabaseUtils.queryNumEntries(db, CONTACTS_TABLE_NAME);
    return numRows;
}

public boolean updateContact(Integer id, String name) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put("name", name);

    db.update("contacts", contentValues, "id = ? ", new String[] { Integer.toString(id) } );
    return true;
}

public Integer deleteContact (Integer id) {
    SQLiteDatabase db = this.getWritableDatabase();
    return db.delete("contacts",
            "id = ? ",
            new String[] { Integer.toString(id) });
}

public ArrayList<String> getAllCotacts() {
    ArrayList<String> array_list = new ArrayList<String>();

    //hp = new HashMap();
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor res =  db.rawQuery( "select * from contacts", null );
    res.moveToFirst();

    while(res.isAfterLast() == false){
        array_list.add(res.getString(res.getColumnIndex(CONTACTS_COLUMN_NAME)));
        res.moveToNext();
    }
    return array_list;
}

devicedetailsActivity

public class devicedetailsActivity extends AppCompatActivity {
public final static String EXTRA_MESSAGE = "MESSAGE";
private ListView obj;
DBHelper mydb;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.devicedetails_layout);
    FullScreencall();
    mydb = new DBHelper(this);
    ArrayList array_list = mydb.getAllCotacts();
    ArrayAdapter arrayAdapter=new ArrayAdapter(this,R.layout.simple_list_item_1, array_list);

    obj = (ListView)findViewById(R.id.listView1);
    obj.setAdapter(arrayAdapter);
    obj.setOnItemClickListener(new AdapterView.OnItemClickListener(){
        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {
            // TODO Auto-generated method stub
            int id_To_Search = arg2 + 1;

            Bundle dataBundle = new Bundle();
            dataBundle.putInt("id", id_To_Search);

            Intent intent = new Intent(getApplicationContext(),DetailsActivity.class);

            intent.putExtras(dataBundle);
            startActivity(intent);
        }
    });
}
public void FullScreencall() {
    if(Build.VERSION.SDK_INT > 11 && Build.VERSION.SDK_INT < 19) { // lower api


        int mUIFlag = View.SYSTEM_UI_FLAG_LOW_PROFILE
                | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                | View.SYSTEM_UI_FLAG_FULLSCREEN;


        getWindow().getDecorView().setSystemUiVisibility(mUIFlag);

    } else if(Build.VERSION.SDK_INT >= 19) {
        //for new api versions.
        View decorView = getWindow().getDecorView();
        int uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
                | View.SYSTEM_UI_FLAG_FULLSCREEN;

        decorView.setSystemUiVisibility(uiOptions);
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    getMenuInflater().inflate(R.menu.home, menu);

    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item){
    super.onOptionsItemSelected(item);

    switch(item.getItemId()) {
        case R.id.item1:Bundle dataBundle = new Bundle();
            dataBundle.putInt("id", 0);

            Intent intent = new Intent(getApplicationContext(),DetailsActivity.class);
            intent.putExtras(dataBundle);

            startActivity(intent);
            return true;
        case R.id.item2: dataBundle = new Bundle();
            dataBundle.putInt("id", 0);
             intent = new Intent(getApplicationContext(),MainActivity.class);
            intent.putExtras(dataBundle);

            startActivity(intent);
            return true;


        default:
            return super.onOptionsItemSelected(item);
    }
}

public boolean onKeyDown(int keycode, KeyEvent event) {
    if (keycode == KeyEvent.KEYCODE_BACK) {
        moveTaskToBack(true);
    }
    return super.onKeyDown(keycode, event);
}

DetailsActivity

public class DetailsActivity extends AppCompatActivity {
int from_Where_I_Am_Coming = 0;
private DBHelper mydb ;

TextView name ;

int id_To_Update = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.details);
    FullScreencall();
    name = (TextView) findViewById(R.id.editTextName);


    mydb = new DBHelper(this);

    Bundle extras = getIntent().getExtras();
    if(extras !=null) {
        int Value = extras.getInt("id");

        if(Value>0){
            //means this is the view part not the add contact part.
            Cursor rs = mydb.getData(Value);
            id_To_Update = Value;
            rs.moveToFirst();
            String nam = rs.getString(rs.getColumnIndex(DBHelper.CONTACTS_COLUMN_NAME));
            if (!rs.isClosed())  {
                rs.close();
            }
            Button b = (Button)findViewById(R.id.button1);
            b.setVisibility(View.INVISIBLE);

            name.setText((CharSequence)nam);
            name.setFocusable(false);
            name.setClickable(false);
        }
    }
}
public void FullScreencall() {
    if(Build.VERSION.SDK_INT > 11 && Build.VERSION.SDK_INT < 19) { // lower api


        int mUIFlag = View.SYSTEM_UI_FLAG_LOW_PROFILE
                | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                | View.SYSTEM_UI_FLAG_FULLSCREEN;


        getWindow().getDecorView().setSystemUiVisibility(mUIFlag);

    } else if(Build.VERSION.SDK_INT >= 19) {
        //for new api versions.
        View decorView = getWindow().getDecorView();
        int uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
                | View.SYSTEM_UI_FLAG_FULLSCREEN;

        decorView.setSystemUiVisibility(uiOptions);
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    Bundle extras = getIntent().getExtras();

    if(extras !=null) {
        int Value = extras.getInt("id");
        if(Value>0){
            getMenuInflater().inflate(R.menu.display_contact, menu);
        } else{
            getMenuInflater().inflate(R.menu.back, menu);
        }
    }
    return true;
}

public boolean onOptionsItemSelected(MenuItem item) {
    super.onOptionsItemSelected(item);
    switch(item.getItemId()) {
        case R.id.Edit_Contact:
            Button b = (Button)findViewById(R.id.button1);
            b.setVisibility(View.VISIBLE);
            name.setEnabled(true);
            name.setFocusableInTouchMode(true);
            name.setClickable(true);


            return true;
        case R.id.Delete_Contact:

            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            builder.setMessage(R.string.deleteContact)
                    .setPositiveButton(R.string.yes, new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            mydb.deleteContact(id_To_Update);
                            Toast.makeText(getApplicationContext(), "Deleted Successfully",
                                    Toast.LENGTH_SHORT).show();
                            Intent intent = new Intent(getApplicationContext(),devicedetailsActivity.class);
                            startActivity(intent);
                        }
                    })
                    .setNegativeButton(R.string.no, new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            // User cancelled the dialog
                        }
                    });

            AlertDialog d = builder.create();
            d.setTitle("Are you sure");
            d.show();

            return true;
        case R.id.back:
            Intent intent = new Intent(getApplicationContext(),devicedetailsActivity.class);
            startActivity(intent);
            return  true;
        default:
            return super.onOptionsItemSelected(item);

    }
}

public void run(View view) {
    Bundle extras = getIntent().getExtras();
    if(extras !=null) {
        int Value = extras.getInt("id");
        if(Value>0){
            if(mydb.updateContact(id_To_Update,name.getText().toString()
                    )){
                Toast.makeText(getApplicationContext(), "Updated", Toast.LENGTH_SHORT).show();
                Intent intent = new Intent(getApplicationContext(),devicedetailsActivity.class);
                startActivity(intent);
            } else{
                Toast.makeText(getApplicationContext(), "not Updated", Toast.LENGTH_SHORT).show();
            }
        } else{
            if(mydb.insertContact(name.getText().toString())){
                Toast.makeText(getApplicationContext(), "done",
                        Toast.LENGTH_SHORT).show();
            } else{
                Toast.makeText(getApplicationContext(), "not done",
                        Toast.LENGTH_SHORT).show();
            }
            Intent intent = new Intent(getApplicationContext(),devicedetailsActivity.class);
            startActivity(intent);
        }
    }
}

Answer 1

此错误表示您没有从数据库中获取任何数据，并且试图访问某些值。

为了避免错误检查游标是否有一些数据。

name = (TextView) findViewById(R.id.editTextName);
    mydb = new DBHelper(this);
    Bundle extras = getIntent().getExtras();
    if(extras !=null) {
        int Value = extras.getInt("id");
        if(Value>0){
            //means this is the view part not the add contact part.
            Cursor rs = mydb.getData(Value);
            //Check if cursor has value
            if(rs != null && rs.getCount() > 0){  
              id_To_Update = Value;
              rs.moveToFirst();
              String nam = rs.getString(rs.getColumnIndex(DBHelper.CONTACTS_COLUMN_NAME));
              if (!rs.isClosed())  {
                  rs.close();
              } 
              Button b = (Button)findViewById(R.id.button1);
              b.setVisibility(View.INVISIBLE);

              name.setText((CharSequence)nam);
              name.setFocusable(false);
              name.setClickable(false);
          }
        }
    }

Answer 2

您需要检查Cursor#moveToFirst的返回值，文档说如果光标为空，moveToFirst返回false。

if(extras !=null) {
    int Value = extras.getInt("id");

    if(Value>0){
        //means this is the view part not the add contact part.
        Cursor rs = mydb.getData(Value);
        if(rs.moveToFirst()) {
            id_To_Update = Value;
            rs.moveToFirst();
            String nam = rs.getString(rs.getColumnIndex(DBHelper.CONTACTS_COLUMN_NAME));
            Button b = (Button)findViewById(R.id.button1);
            b.setVisibility(View.INVISIBLE);

            name.setText((CharSequence)nam);
            name.setFocusable(false);
            name.setClickable(false);
        }
        if (!rs.isClosed())  {
            rs.close();
        }
    }
}

CursorIndexOutOfBoundsException错误-数据库Android

2 个答案: