Android 将数据从数据库传递到活动

我正在开发一个应用程序，当我按下按钮时，它会在地图上显示位置

但是，我想从数据库中获取这个按钮正在接收的纬度和经度数据

我已经有了一个名为“DetaljiProizvoda”的活动，它可以从数据库中获取项目的详细信息，并且我已经在数据库中添加了（在DatabaseHelper.java文件中）latitude和longitude的int类型的列

我想将纬度和经度数据传递到gmapactivity.java文件，并使用它们显示地图上每个项目的位置

我在LogCat中发现这些错误，请帮助：

09-23 18:07:52.986: E/AndroidRuntime(22995): FATAL EXCEPTION: main
09-23 18:07:52.986: E/AndroidRuntime(22995): java.lang.IllegalStateException: Could not execute method of the activity
09-23 18:07:52.986: E/AndroidRuntime(22995):    at android.view.View$1.onClick(View.java:3044)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at android.view.View.performClick(View.java:3511)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at android.view.View$PerformClick.run(View.java:14105)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at android.os.Handler.handleCallback(Handler.java:605)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at android.os.Handler.dispatchMessage(Handler.java:92)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at android.os.Looper.loop(Looper.java:137)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at android.app.ActivityThread.main(ActivityThread.java:4424)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at java.lang.reflect.Method.invokeNative(Native Method)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at java.lang.reflect.Method.invoke(Method.java:511)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at dalvik.system.NativeStart.main(Native Method)
09-23 18:07:52.986: E/AndroidRuntime(22995): Caused by: java.lang.reflect.InvocationTargetException
09-23 18:07:52.986: E/AndroidRuntime(22995):    at java.lang.reflect.Method.invokeNative(Native Method)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at java.lang.reflect.Method.invoke(Method.java:511)
09-23 18:07:52.986: E/AndroidRuntime(22995):    at android.view.View$1.onClick(View.java:3039)
09-23 18:07:52.986: E/AndroidRuntime(22995):    ... 11 more
09-23 18:07:52.986: E/AndroidRuntime(22995): Caused by: java.lang.NullPointerException
09-23 18:07:52.986: E/AndroidRuntime(22995):    at hr.punctum.LociranjePonudaProizvoda.DetaljiProizvoda.changeActivity(DetaljiProizvoda.java:66)
09-23 18:07:52.986: E/AndroidRuntime(22995):    ... 14 more

DetaljiProizvoda.java

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

        proizvodId = getIntent().getIntExtra("PROIZVODI_ID", 0);
        SQLiteDatabase db = (new DatabaseHelper(this)).getWritableDatabase();
        Cursor cursor = db.rawQuery("SELECT proizv._id, proizv.naziv, proizv.tvrtka, proizv.cijena, proizv.kategorija, proizv.telefonTvrtke, proizv.adresaTvrtke, proizv.latitude, proizv.longitude FROM proizvodi proizv LEFT OUTER JOIN proizvodi mgr ON proizv._id = mgr._id WHERE proizv._id = ?", 
                new String[]{""+proizvodId});

        if (cursor.getCount() == 1)
        {
            cursor.moveToFirst();

            naziv = (TextView) findViewById(R.id.naziv);
            naziv.setText(cursor.getString(cursor.getColumnIndex("naziv"))); 

            kategorija = (TextView) findViewById(R.id.kategorija);
            kategorija.setText(cursor.getString(cursor.getColumnIndex("kategorija")));

            tvrtka = (TextView) findViewById(R.id.tvrtka);
            tvrtka.setText(cursor.getString(cursor.getColumnIndex("tvrtka")));

            telefonTvrtke = (TextView) findViewById(R.id.telefonTvrtke);
            telefonTvrtke.setText(cursor.getString(cursor.getColumnIndex("telefonTvrtke")));

            adresaTvrtke = (TextView) findViewById(R.id.adresaTvrtke);
            adresaTvrtke.setText(cursor.getString(cursor.getColumnIndex("adresaTvrtke")));

        }

        cursor.close();
        db.close(); 

    }

      public void changeActivity(View view) { 

        Intent intent = new Intent(DetaljiProizvoda.this, GMapsActivity.class);

            intent.putExtra("PROIZVODI_ID", cursor.getColumnIndex("_id"));
            intent.putExtra("PROIZVODI_LATITUDE", cursor.getColumnIndex("latitude"));
            intent.putExtra("PROIZVODI_LONGITUDE", cursor.getColumnIndex("longitude"));
            startActivity(intent);                    

        }                    

    } 

package hr.punctum.LociranjePonudaProizvoda;    

public class ListaProizvoda extends ListActivity {

    protected EditText searchText;
    protected SQLiteDatabase db;
    protected Cursor cursor;
    protected ListAdapter adapter;


    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        db = (new DatabaseHelper(this)).getWritableDatabase();
        searchText = (EditText) findViewById (R.id.searchText);

    }    

    @SuppressWarnings("deprecation")
    //kreiranje metode Search za pretraživanje proizvoda u bazi podataka
    public void search(View view) {
        // slijedeci sql query vraca rezultat iz baze svih zapisa koji pocinju na slovo uneseno u search polje
        cursor = db.rawQuery("SELECT _id, naziv, tvrtka, cijena FROM proizvodi WHERE naziv LIKE ?", 
                        new String[]{searchText.getText().toString() + "%"}); 
        adapter = new SimpleCursorAdapter(this,R.layout.proizvodi_list_artikl,cursor,new String[] {"naziv", "tvrtka", "cijena"},new int[] {R.id.naziv, R.id.tvrtka, R.id.cijena});

        setListAdapter(adapter);

    }

    public void onListItemClick(ListView parent, View view, int position, long id) {
        //kreiranje Intenta za komunikaciju s drugim activity-om
        Intent intent = new Intent(this, DetaljiProizvoda.class);
        Cursor cursor = (Cursor) adapter.getItem(position);
        //slanje varijable
        intent.putExtra("PROIZVODI_ID", cursor.getInt(cursor.getColumnIndex("_id")));
        startActivity(intent);

    }      

gmapactivity.java

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

        proizvodId = getIntent().getIntExtra("PROIZVODI_ID", 0);
        SQLiteDatabase db = (new DatabaseHelper(this)).getWritableDatabase();
        Cursor cursor = db.rawQuery("SELECT proizv._id, proizv.naziv, proizv.tvrtka, proizv.cijena, proizv.kategorija, proizv.telefonTvrtke, proizv.adresaTvrtke, proizv.latitude, proizv.longitude FROM proizvodi proizv LEFT OUTER JOIN proizvodi mgr ON proizv._id = mgr._id WHERE proizv._id = ?", 
                new String[]{""+proizvodId});

        if (cursor.getCount() == 1)
        {
            cursor.moveToFirst();

            naziv = (TextView) findViewById(R.id.naziv);
            naziv.setText(cursor.getString(cursor.getColumnIndex("naziv"))); 

            kategorija = (TextView) findViewById(R.id.kategorija);
            kategorija.setText(cursor.getString(cursor.getColumnIndex("kategorija")));

            tvrtka = (TextView) findViewById(R.id.tvrtka);
            tvrtka.setText(cursor.getString(cursor.getColumnIndex("tvrtka")));

            telefonTvrtke = (TextView) findViewById(R.id.telefonTvrtke);
            telefonTvrtke.setText(cursor.getString(cursor.getColumnIndex("telefonTvrtke")));

            adresaTvrtke = (TextView) findViewById(R.id.adresaTvrtke);
            adresaTvrtke.setText(cursor.getString(cursor.getColumnIndex("adresaTvrtke")));

        }

        cursor.close();
        db.close(); 

    }

      public void changeActivity(View view) { 

        Intent intent = new Intent(DetaljiProizvoda.this, GMapsActivity.class);

            intent.putExtra("PROIZVODI_ID", cursor.getColumnIndex("_id"));
            intent.putExtra("PROIZVODI_LATITUDE", cursor.getColumnIndex("latitude"));
            intent.putExtra("PROIZVODI_LONGITUDE", cursor.getColumnIndex("longitude"));
            startActivity(intent);                    

        }                    

    } 

package hr.punctum.LociranjePonudaProizvoda;    

public class ListaProizvoda extends ListActivity {

    protected EditText searchText;
    protected SQLiteDatabase db;
    protected Cursor cursor;
    protected ListAdapter adapter;


    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        db = (new DatabaseHelper(this)).getWritableDatabase();
        searchText = (EditText) findViewById (R.id.searchText);

    }    

    @SuppressWarnings("deprecation")
    //kreiranje metode Search za pretraživanje proizvoda u bazi podataka
    public void search(View view) {
        // slijedeci sql query vraca rezultat iz baze svih zapisa koji pocinju na slovo uneseno u search polje
        cursor = db.rawQuery("SELECT _id, naziv, tvrtka, cijena FROM proizvodi WHERE naziv LIKE ?", 
                        new String[]{searchText.getText().toString() + "%"}); 
        adapter = new SimpleCursorAdapter(this,R.layout.proizvodi_list_artikl,cursor,new String[] {"naziv", "tvrtka", "cijena"},new int[] {R.id.naziv, R.id.tvrtka, R.id.cijena});

        setListAdapter(adapter);

    }

    public void onListItemClick(ListView parent, View view, int position, long id) {
        //kreiranje Intenta za komunikaciju s drugim activity-om
        Intent intent = new Intent(this, DetaljiProizvoda.class);
        Cursor cursor = (Cursor) adapter.getItem(position);
        //slanje varijable
        intent.putExtra("PROIZVODI_ID", cursor.getInt(cursor.getColumnIndex("_id")));
        startActivity(intent);

    }      

公共类GmapActivity扩展了MapActivity{

private MapView mapView;
protected int latitudeE6;
protected int longitudeE6;  



@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.gmaps_layout);

    latitudeE6 = getIntent().getIntExtra("PROIZVODI_LATITUDE", 0);       
    longitudeE6 = getIntent().getIntExtra("PROIZVODI_LONGITUDE", 0);      

    mapView = (MapView) findViewById(R.id.map_view);       
    mapView.setBuiltInZoomControls(true);

    List<Overlay> mapOverlays = mapView.getOverlays();
    Drawable drawable = this.getResources().getDrawable(R.drawable.icon);
    CustomItemizedOverlay itemizedOverlay = new CustomItemizedOverlay(drawable, this);

    GeoPoint point = new GeoPoint(latitudeE6, longitudeE6);
    OverlayItem overlayitem = new OverlayItem(point, "Dobrodošli u " , "tvrtku Protis");

    itemizedOverlay.addOverlay(overlayitem);
    mapOverlays.add(itemizedOverlay);

    MapController mapController = mapView.getController();

    mapController.animateTo(point);
    mapController.setZoom(18);

}

@Override
protected boolean isRouteDisplayed() {
    return false;
}

DatabaseHelper.java

public class DatabaseHelper extends SQLiteOpenHelper {

    public static final String DATABASE_NAME = "proizvodidb";

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 4);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

        String sql = "CREATE TABLE IF NOT EXISTS proizvodi (" +
                        "_id INTEGER PRIMARY KEY AUTOINCREMENT, " + 
                        "naziv TEXT, " +
                        "tvrtka TEXT, " +
                        "cijena TEXT, " +
                        "kategorija TEXT, " +
                        "telefonTvrtke TEXT, " +
                        "adresaTvrtke TEXT, " +
                        "latitude INTEGER, " +
                        "longitude INTEGER)";

        db.execSQL(sql);

        ContentValues values = new ContentValues();

        values.put("naziv", "Nikon D800");
        values.put("tvrtka", "MagazinRS");
        values.put("cijena", "21600");
        values.put("kategorija", "fotoaparati");
        values.put("telefonTvrtke", "454562542");
        values.put("adresaTvrtke", "Laniste 1B");
        values.put("latitude", 458011234);
        values.put("longitude", 159520583);
        db.insert("proizvodi", "tvrtka", values);   

        ....        

    }


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

}

detalji_proizvoda.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:paddingTop="12dp"
    android:paddingLeft="12dp">

    <TextView
        android:id="@+id/naziv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/kategorija"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/tvrtka"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/telefonTvrtke"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/adresaTvrtke"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>      
    <Button 
        android:id="@+id/btnButton"
        android:layout_height="wrap_content"
        android:layout_width="fill_parent"
        android:layout_gravity="left"
        android:onClick="changeActivity"
        android:text="@string/prikazi_lokaciju"
        android:textSize="12dp" />

</LinearLayout>

logcat:

09-23 22:46:14.652: E/AndroidRuntime(680): FATAL EXCEPTION: main
09-23 22:46:14.652: E/AndroidRuntime(680): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{hr.punctum.LociranjePonudaProizvoda/hr.punctum.LociranjePonudaProizvoda.ListaProizvoda}: java.lang.ClassNotFoundException: hr.punctum.LociranjePonudaProizvoda.ListaProizvoda
09-23 22:46:14.652: E/AndroidRuntime(680):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1880)
09-23 22:46:14.652: E/AndroidRuntime(680):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
09-23 22:46:14.652: E/AndroidRuntime(680):  at android.app.ActivityThread.access$600(ActivityThread.java:123)
09-23 22:46:14.652: E/AndroidRuntime(680):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
09-23 22:46:14.652: E/AndroidRuntime(680):  at android.os.Handler.dispatchMessage(Handler.java:99)
09-23 22:46:14.652: E/AndroidRuntime(680):  at android.os.Looper.loop(Looper.java:137)
09-23 22:46:14.652: E/AndroidRuntime(680):  at android.app.ActivityThread.main(ActivityThread.java:4424)
09-23 22:46:14.652: E/AndroidRuntime(680):  at java.lang.reflect.Method.invokeNative(Native Method)
09-23 22:46:14.652: E/AndroidRuntime(680):  at java.lang.reflect.Method.invoke(Method.java:511)
09-23 22:46:14.652: E/AndroidRuntime(680):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
09-23 22:46:14.652: E/AndroidRuntime(680):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
09-23 22:46:14.652: E/AndroidRuntime(680):  at dalvik.system.NativeStart.main(Native Method)
09-23 22:46:14.652: E/AndroidRuntime(680): Caused by: java.lang.ClassNotFoundException: hr.punctum.LociranjePonudaProizvoda.ListaProizvoda
09-23 22:46:14.652: E/AndroidRuntime(680):  at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
09-23 22:46:14.652: E/AndroidRuntime(680):  at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
09-23 22:46:14.652: E/AndroidRuntime(680):  at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
09-23 22:46:14.652: E/AndroidRuntime(680):  at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
09-23 22:46:14.652: E/AndroidRuntime(680):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1871)
09-23 22:46:14.652: E/AndroidRuntime(680):  ... 11 more

---

在onCreate（）方法的末尾关闭光标。然后在方法changeActivity（）中尝试使用它。

首先尝试检查光标是否为null，而不是（cursor.getCount（）==1）我为什么要这样做？我的意思是为什么游标必须为null？如果没有获得的数据，那么游标将没有数据，它将为null，并且使用游标。getCount（）可能会给您带来麻烦。我明白了，谢谢。但这并不能解决问题。否则，我认为您正在调用changeActivity（）在类外，没有为类创建对象。您在哪里使用了changeActivity（）？我已经更改了此设置，但我的应用程序在进入上一个活动（GmapActivity）时仍处于崩溃状态，即在显示地图位置时。您能否编写完整代码？您能否提供新的logcat（解决光标问题后的logcat）如我所见，我在一开始就这样做了。我在onCreate（）方法的末尾关闭了游标，然后我尝试在changeActivity（）中使用它。那么我做错了什么？你不应该在onCreate方法的末尾关闭游标。当你这样做并使用intent.putExtra（“PROIZVODI_ID”，cursor.getColumnIndex（“u ID”））；您在hr.punctum.lociranjepenudaproizvoda.DetaljiProizvoda.changeActivity（DetaljiProizvoda.java:66）处得到错误。请在代码中修复该错误，然后在应用程序仍然崩溃的情况下提供一个新的logcat。我添加了新的logcat。现在，我在changeActivity方法的末尾关闭了游标。db.close（）是以前的位置，可以吗？