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我已经尝试使用 commonsware 示例

这是活动

public class ConstantsBrowser extends ListActivity {
  private LocationManager lm;
  private LocationListener locListener;
  private TextView latTxt, lonTxt;
  private double dLat=0;
  private double dLon=0;
  Intent intent = null;
  private static final int ADD_ID = Menu.FIRST+1;
  private static final int DELETE_ID = Menu.FIRST+3;
  private static final int UPDATE_ID = Menu.FIRST+4;
  public static final int SHOW_SUB_ACTIVITY_VIEW=3;
  private DatabaseHelper db=null;
  private Cursor constantsCursor=null;

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

    latTxt = (TextView) findViewById(R.id.latitudeTxt);
    lonTxt = (TextView) findViewById(R.id.longitudeTxt);

    lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    locListener = new MyLocationListener();
    lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10, 10,locListener);

    db=new DatabaseHelper(this);
    constantsCursor=db
                      .getReadableDatabase()
                      .rawQuery("SELECT _ID, title, value "+
                                "FROM constants ORDER BY _ID",
                                null);

    ListAdapter adapter=new SimpleCursorAdapter(this,
                          R.layout.row, constantsCursor,
                          new String[] {
                                        DatabaseHelper.ID,
                                        DatabaseHelper.TITLE,
                                        DatabaseHelper.VALUE},
                          new int[] {R.id.id, R.id.alamat, R.id.value});

    setListAdapter(adapter);
    registerForContextMenu(getListView());
  }

  @Override
  public void onDestroy() {
    super.onDestroy();

    constantsCursor.close();
    db.close();
  }

  private class MyLocationListener implements LocationListener {
        @Override
        public void onLocationChanged(Location loc) {
            // TODO Auto-generated method stub
            if (loc != null) {
                latTxt.setText(String.valueOf(loc.getLatitude()));
                lonTxt.setText(String.valueOf(loc.getLongitude()));
            }
        }

        @Override
        public void onProviderDisabled(String provider) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onProviderEnabled(String provider) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onStatusChanged(String provider, int status, Bundle extras) {
            // TODO Auto-generated method stub

        }

    }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    menu.add(Menu.NONE, ADD_ID, Menu.NONE, "Data Baru")
        .setIcon(R.drawable.add)
        .setAlphabeticShortcut('a');

    return(super.onCreateOptionsMenu(menu));
  }

  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
      case ADD_ID:
        add();
        return(true);
    }

    return(super.onOptionsItemSelected(item));
  }

  @Override
  public void onCreateContextMenu(ContextMenu menu, View v,
                                    ContextMenu.ContextMenuInfo menuInfo) {
    menu.add(Menu.NONE, DELETE_ID, Menu.NONE, "Delete");
    menu.add(Menu.NONE, UPDATE_ID, Menu.NONE, "Update")
        .setAlphabeticShortcut('d');
  }

  @Override
  public boolean onContextItemSelected(MenuItem item) {
    switch (item.getItemId()) {
      case DELETE_ID:
        AdapterView.AdapterContextMenuInfo info=
          (AdapterView.AdapterContextMenuInfo)item.getMenuInfo();

        delete(info.id);
        return(true);

      case UPDATE_ID:
          intent = new Intent(ConstantsBrowser.this, MainActivity.class);
            startActivityForResult(intent, SHOW_SUB_ACTIVITY_VIEW);
          return(true);
    }

    return(super.onOptionsItemSelected(item));
  }

  private void add() {
    LayoutInflater inflater=LayoutInflater.from(this);
    View addView=inflater.inflate(R.layout.add_edit, null);
    final DialogWrapper wrapper=new DialogWrapper(addView);

    new AlertDialog.Builder(this)
      .setTitle(R.string.add_title)
      .setView(addView)
      .setPositiveButton(R.string.ok,
                          new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog,
                              int whichButton) {
          processAdd(wrapper);
        }
      })
      .setNegativeButton(R.string.cancel,
                          new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog,
                              int whichButton) {
          // ignore, just dismiss
        }
      })
      .show();
  }

  private void delete(final long rowId) {
    if (rowId>0) {
      new AlertDialog.Builder(this)
        .setTitle(R.string.delete_title)
        .setPositiveButton(R.string.ok,
                            new DialogInterface.OnClickListener() {
          public void onClick(DialogInterface dialog,
                                int whichButton) {
            processDelete(rowId);
          }
        })
        .setNegativeButton(R.string.cancel,
                            new DialogInterface.OnClickListener() {
          public void onClick(DialogInterface dialog,
                                int whichButton) {
          // ignore, just dismiss
          }
        })
        .show();
    }
  }

  private void processAdd(DialogWrapper wrapper) {
    ContentValues values=new ContentValues(2);

    values.put(DatabaseHelper.TITLE, wrapper.getTitle());
    values.put(DatabaseHelper.VALUE, wrapper.getValue());

    db.getWritableDatabase().insert("constants", DatabaseHelper.TITLE, values);
    constantsCursor.requery();
  }

  private void processDelete(long rowId) {
    String[] args={String.valueOf(rowId)};

    db.getWritableDatabase().delete("constants", "_ID=?", args);
    constantsCursor.requery();
  }

  class DialogWrapper {
    EditText titleField=null;
    EditText valueField=null;
    View base=null;

    DialogWrapper(View base) {
      this.base=base;
      valueField=(EditText)base.findViewById(R.id.value);
    }

    String getTitle() {
      return(getTitleField().getText().toString());
    }

    String getValue() {
      return(getValueField().getText().toString());
    }

    private EditText getTitleField() {
      if (titleField==null) {
        titleField=(EditText)base.findViewById(R.id.title);
      }

      return(titleField);
    }

    private EditText getValueField() {
      if (valueField==null) {
        valueField=(EditText)base.findViewById(R.id.value);
      }

      return(valueField);
    }
  }
}

我在这个活动中添加了 gps，但是当我尝试应用程序时强制关闭

这是清单

我添加一个权限

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" >
    </uses-permission>
    <uses-permission android:name="android.permission.INTERNET" >
    </uses-permission>
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" >
    </uses-permission>
    <uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION" />
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
    <uses-permission android:name="android.permission.CAMERA" >

这是 logcat 空指针异常

02-20 12:07:32.203: ERROR/AndroidRuntime(8904): FATAL EXCEPTION: main
02-20 12:07:32.203: ERROR/AndroidRuntime(8904): java.lang.NullPointerException
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at com.commonsware.android.constants.ConstantsBrowser$MyLocationListener.onLocationChanged(ConstantsBrowser.java:98)
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at android.location.LocationManager$ListenerTransport._handleMessage(LocationManager.java:227)
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at android.location.LocationManager$ListenerTransport.access$000(LocationManager.java:160)
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at android.location.LocationManager$ListenerTransport$1.handleMessage(LocationManager.java:176)
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at android.os.Handler.dispatchMessage(Handler.java:99)
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at android.os.Looper.loop(Looper.java:130)
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at android.app.ActivityThread.main(ActivityThread.java:3683)
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at java.lang.reflect.Method.invokeNative(Native Method)
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at java.lang.reflect.Method.invoke(Method.java:507)
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-20 12:07:32.203: ERROR/AndroidRuntime(8904):     at dalvik.system.NativeStart.main(Native Method)
02-20 12:07:32.226: WARN/ActivityManager(1308):   Force finishing activity com.commonsware.android.constants/.ConstantsBrowser

空值在行latTxt.setText(String.valueOf(loc.getLatitude()));

如何解决？

4

1 回答 1

1

latTxt一片空白。确保您的布局 XML 文件中有一个<TextView>带有 id的。@+id/latitudeTxt

于 2013-02-20T06:03:13.950 回答