Question

我从服务器JSON获取值并存储到本地数据库中。我收到了JSON数组，我在logcat消息中看到了这个，但是当我习惯将值存储到本地数据库中时，我收到了错误。

public class DataBaseHandler extends SQLiteOpenHelper {

     public DataBaseHandler(Context context, String name, CursorFactory factory,
            int version) {

        // TODO Auto-generated constructor stub

           super(context, DATABASE_NAME, null, DATABASE_VERSION);
            context = this.context;
    }

    Context context ;

        // All Static variables
        // Database Version
        private static final int DATABASE_VERSION = 1;

        // Database Name
        private static final String DATABASE_NAME = "BeaconDetails";

        // Contacts table name
        //table 1
        private static final String TABLE_BEACON = "beacon_details";

       // Contacts Table Columns names

        //table 1
        private static final String KEY_UUID = "uuid";
        private static final String KEY_NAME = "name";
        private static final String KEY_NOTIFICATION = "notification";
        private static final String KEY_TYPE = "type";
        private static final String KEY_MAJOR_ID = "major";
        private static final String KEY_MINOR_ID = "minor";


    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub


        String CREATE_TABLE_BEACON = "CREATE TABLE " + TABLE_BEACON + "("
                + KEY_NAME + " TEXT,"+ KEY_UUID + " INTEGER PRIMARY KEY,"+ KEY_MAJOR_ID + " INTEGER PRIMARY KEY,"+ KEY_MINOR_ID + " INTEGER PRIMARY KEY"+ KEY_NOTIFICATION + " TEXT,"+ KEY_TYPE + " TEXT)";
        db.execSQL(CREATE_TABLE_BEACON);

    }

     // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_BEACON);

        // Create tables again
        onCreate(db);

    }

    public long insertBeaconDetails(BeaconDetails beacondetailstore) 
    {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();

         values.put(KEY_NAME,beacondetailstore.name);
         values.put(KEY_UUID,beacondetailstore.uuid);
         values.put(KEY_MAJOR_ID,beacondetailstore.major);
         values.put(KEY_MINOR_ID,beacondetailstore.minor);
         values.put(KEY_NOTIFICATION,beacondetailstore.notification);
         values.put(KEY_TYPE,beacondetailstore.type);       


         long rowId = db.replace(TABLE_BEACON, null, values);
         db.close();
         return rowId;
    }

MainActivity.java：

 @Override
    protected Void doInBackground(Void... voids) {
        try {
            String jsonString = getJsonString();
            Log.v(TAG, "json: " + jsonString);

            JSONArray jsonRegions = new JSONArray(jsonString);
            for (int i = 0; i < jsonRegions.length(); i++) {
                JSONObject jsonRegion = jsonRegions.getJSONObject(i);

                beacondetailstore = new BeaconDetails();

                beacondetailstore.name = jsonRegion.getString("name");
                beacondetailstore.uuid = jsonRegion.getString("uuid");
                beacondetailstore.major = jsonRegion.getInt("major_id");
                beacondetailstore.minor = jsonRegion.getInt("minor_id");               
                beacondetailstore.notification=jsonRegion.getString("notification");
                beacondetailstore.type = jsonRegion.getString("type");

               db.insertBeaconDetails(beacondetailstore);


            }
        } catch (JSONException e) {
            e.printStackTrace();

            Log.d("myTag", e.getMessage());
        }

记录值：

11-15 11:11:02.280: E/AndroidRuntime(15702): FATAL EXCEPTION: AsyncTask #1
11-15 11:11:02.280: E/AndroidRuntime(15702): java.lang.RuntimeException: An error occured while executing doInBackground()
11-15 11:11:02.280: E/AndroidRuntime(15702):    at android.os.AsyncTask$3.done(AsyncTask.java:299)
11-15 11:11:02.280: E/AndroidRuntime(15702):    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
11-15 11:11:02.280: E/AndroidRuntime(15702):    at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
11-15 11:11:02.280: E/AndroidRuntime(15702):    at java.util.concurrent.FutureTask.run(FutureTask.java:239)
11-15 11:11:02.280: E/AndroidRuntime(15702):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
11-15 11:11:02.280: E/AndroidRuntime(15702):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
11-15 11:11:02.280: E/AndroidRuntime(15702):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
11-15 11:11:02.280: E/AndroidRuntime(15702):    at java.lang.Thread.run(Thread.java:841)
11-15 11:11:02.280: E/AndroidRuntime(15702): Caused by: java.lang.NullPointerException
11-15 11:11:02.280: E/AndroidRuntime(15702):    at com.estimote.examples.demos.NotifyDemoActivity$JsonTask.doInBackground(NotifyDemoActivity.java:141)
11-15 11:11:02.280: E/AndroidRuntime(15702):    at com.estimote.examples.demos.NotifyDemoActivity$JsonTask.doInBackground(NotifyDemoActivity.java:1)
11-15 11:11:02.280: E/AndroidRuntime(15702):    at android.os.AsyncTask$2.call(AsyncTask.java:287)
11-15 11:11:02.280: E/AndroidRuntime(15702):    at java.util.concurrent.FutureTask.run(FutureTask.java:234)
11-15 11:11:02.280: E/AndroidRuntime(15702):    ... 4 more

140th行是db.insertBeaconDetails(beacondetailstore);

Answer 1

错误有两种选择和替代解决方案。

1）问题是由于你的错误Context。

2）您尚未初始化db课程。所以你需要在onCreate()方法上初始化它。

 db = new DataBaseHandler(this, "BeaconDetails", null, 1)

值未插入本地数据库

1 个答案: