Android 当我点击“开始”按钮进行邻近响应时，它会使我的应用程序崩溃

当我点击按钮时，它调用

setProximityAlert（）

函数，然后将显示Toast。我不明白问题出在哪里

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.locations);

    Button start = (Button) findViewById(R.id.startl);
    start.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            setProximityAlert();
            Toast.makeText(getBaseContext(), "Started", Toast.LENGTH_LONG).show();

        }
    });

}

private static final String MMH_PROXIMITY_ALERT = "com.example.ProximityAlert";
private void setProximityAlert() {
    Cursor c = db.rawQuery("SELECT * from locations", null);

    Double lng = c.getDouble(c.getColumnIndex("longitude"));
    c.moveToNext();

    Double lat = c.getDouble(c.getColumnIndex("latitude"));
    c.moveToNext();

    Float rds = c.getFloat(c.getColumnIndex("radius"));
    c.moveToNext();

    String locService = Context.LOCATION_SERVICE;
    LocationManager locationManager;
    locationManager = (LocationManager)getSystemService(locService);

    long expiration = -1; // do not expire
    Intent intent = new Intent(MMH_PROXIMITY_ALERT);
    PendingIntent proximityIntent = PendingIntent.getBroadcast(this, -1, intent, 0);
    locationManager.addProximityAlert(lat, lng, rds, expiration, proximityIntent);
    c.close();

    locationManager.addProximityAlert(
        lat, // the latitude of the central point of the alert region
        lng, // the longitude of the central point of the alert region
        rds, // the radius of the central point of the alert region, in meters
        expiration, // time for this proximity alert, in milliseconds, or -1 to indicate no                           expiration
        proximityIntent // will be used to generate an Intent to fire when entry to or exit from the alert region is detected
    );

    IntentFilter filter = new IntentFilter(MMH_PROXIMITY_ALERT);
    registerReceiver(new ProximityIntentReceiver(), filter);
}

---

在尝试访问光标数据之前，请在光标上使用

moveToFirst

方法。

DBAdapter类：

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

    public class DBAdapter {

        // Common params
        private static final int DATABASE_VERSION = 1;
        private final Context context;
        private DatabaseHelper DBHelper;
        private SQLiteDatabase db; 
        public static final String DATABASE_NAME = "db_name";

        public DBAdapter(Context ctx) {
            this.context = ctx;
            DBHelper = new DatabaseHelper(context);
        }

        private static class DatabaseHelper extends SQLiteOpenHelper {
            DatabaseHelper(Context context) {
                super(context, DATABASE_NAME, null, DATABASE_VERSION);
            }

            public void onCreate(SQLiteDatabase db) {
                db.execSQL(CREATE_MY_TABLE);
            }

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

        // ---open database---
        public DBAdapter open() throws SQLException {
            db = DBHelper.getWritableDatabase();
            return this;
        }

        // ---closes database---
        public void close() {
            DBHelper.close();
        }

        // --- Table ---
        public static final String MY_TABLE = "my_tbl";
        public static final String COLUMN_ID = "id";
        public static final String COLUMN_USER_ID = "user_id";
        public static final String COLUMN_TITLE = "title";

        private static final String CREATE_MY_TABLE = "create table "
                + MY_TABLE + "(" + COLUMN_ID
                + " text not null, " + COLUMN_USER_ID
                + " text not null, " + COLUMN_TITLE
                + " text not null);";

        // ---insert data in database---
        public long insertData(Model model) {

            ContentValues initialValues = new ContentValues();
            initialValues.put(COLUMN_ID, model.getId());
            initialValues.put(COLUMN_USER_ID, model.getUserId());
            initialValues.put(COLUMN_TITLE, model.getTitle());

            return db.insert(MY_TABLE, null, initialValues);
        }

        // ---get all table's data---
        public Cursor getAllData() {
            return db.query(MY_TABLE, GET_DATA(), null, null,
                    null, null, null);
        }

        // ---deletes all table's data---
        public void deleteAllTables() {
            SQLiteDatabase db = DBHelper.getWritableDatabase();
            db.delete(MY_TABLE, null, null);
        }

        // ---updates a table's details---
        public boolean updateTable(String id, String title) {
            ContentValues initialValues = new ContentValues();

            // update any field
    //      initialValues.put(COLUMN_TITLE, title);
            return db.update(MY_TABLE, initialValues,
                    COLUMN_ID + "=" + id, null) > 0;
        }

        private static String[] GET_DATA(){
             String[] getArray =  new String []{ COLUMN_ID, COLUMN_USER_ID,COLUMN_TITLE };
            return getArray;
        }   
    } 

如何使用它

专用数据库适配器数据库

db = new DBAdapter(mContext);

在从数据库中提取数据之前，是否打开数据库，如：

db.open();

db.close();

开始使用光标按查询获取数据

Cursor cur = db.getAllData();

if(cur!=null && cur.getCount()>0){
  cur.moveToFirst();

  for(int i = 0; i < cur.getCount(); i++)

// Here get all data from cursor

    cur.movetoNext();
  }

cur.close();

---

logcat窗口中的错误是什么？您能在这里提供清单文件内容吗？如何发布logcat plz帮助它太大，无法进行评论找到包含单词“异常”和“原因”的红色块。它通常位于应用程序之后的logcat内容末尾crashed@sarfraz你试过我编辑过的答案吗？先生，谢谢你的回答，我真的没有用过这些东西。Plz I使用db=openOrCreateDatabase（“EventsDB”，Context.MODE_PRIVATE，null）创建了db；execSQL（“如果不存在位置（名称VarChar、纬度双精度、经度双精度、半径浮点）则创建表；”；在这种情况下我可以使用DBAdapter吗。这段代码对DBAdapter足够了吗；db=新的DBAdapter（mContext）；它在oncreat和setProximityAlert（）db.open（）中给出了一个错误；太给了一个错误，谢谢先生，因为下面的回答对我有效，所以我不能尝试你的鳕鱼，但谢谢你的帮助。