Question

每当我运行代码应用程序在实例化助手类后崩溃。我是新手，无法弄清楚错误。

我的合同类

public final class PetContract {
    private PetContract(){}
    public static class PetEntry implements BaseColumns{
        public static final String TABLE_NAME = "pets";
        public static final String _ID = BaseColumns._ID;
        public static final String COLUMN_NAME = "name";
        public static final String COLUMN_BREED = "breed";
        public static final String COLUMN_GENDER = "gender";
        public static final String COLUMN_WEIGHT = "weight";
        // constants for gender
        public static final int GENDER_UNKNOWN = 0;
        public static final int GENDER_MALE = 1;
        public static final int GENDER_FEMALE = 2;
    }
}

我的SQLiteHelperClass

public class PetDbHelper extends SQLiteOpenHelper {
    public static final int DATABASE_VERSION = 1;
    public static final String DATABASE_NAME = "pets.db";
    public static final String SQL_CREATE_ENTRIES = "CREATE TABLE " + PetEntry.TABLE_NAME + " ( "
            + PetEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
            + PetEntry.COLUMN_NAME + " TEXT NOT NULL, "
            + PetEntry.COLUMN_BREED + " TEXT NOT NULL, "
            + PetEntry.COLUMN_GENDER + " INTEGER NOT NULL, "
            + PetEntry.COLUMN_WEIGHT + " FLOAT NOT NULL "
            + ")";
    private static final String SQL_DELETE_ENTRIES =
            "DROP TABLE IF EXISTS " + PetEntry.TABLE_NAME;
    public PetDbHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }


    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(SQL_CREATE_ENTRIES);
        onCreate(db);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

主要活动

public class CatalogActivity extends AppCompatActivity {
    PetDbHelper mDbHelper = new PetDbHelper(this);
    public void insertDummyData(){
        SQLiteDatabase db = mDbHelper.getWritableDatabase();
        ContentValues values = new ContentValues();
        String name = "DOG";
        String breed = "dkdsbk";
        float weight = (float) 55.5;
        values.put(PetEntry.COLUMN_NAME,name);
        values.put(PetEntry.COLUMN_BREED, breed);
        values.put(PetEntry.COLUMN_GENDER,PetEntry.GENDER_MALE);
        values.put(PetEntry.COLUMN_WEIGHT,weight);
        long newRowId = db.insert(PetEntry.TABLE_NAME,null,values);
    }
    public Cursor displayRowCount(){
        SQLiteDatabase db = mDbHelper.getReadableDatabase();
        String[] projection = {PetEntry._ID};
        String selection = PetEntry.TABLE_NAME;
        return db.query(PetEntry.TABLE_NAME,projection,null,null,null,null,null);

   }


    @Override
        protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_catalog);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(CatalogActivity.this,EditorialActivity.class );
                startActivity(intent);
            }
        });
        Cursor c = displayRowCount();
        TextView view = (TextView) findViewById(R.id.text);
        view.setText("The row count is" + c.getCount());
    }

    @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_catalog, menu);
        return true;
    }


    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        switch (id){
            case R.id.delete_all_the_pets:
                break;
            case R.id.insert_dummy_data:
                insertDummyData();
                break;
        }

        return super.onOptionsItemSelected(item);
    }
}

Answer 1

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(SQL_CREATE_ENTRIES);
    onCreate(db);
}

这是一个递归函数!!

请勿打电话给创建内部onCreate

在我的Android应用程序中执行getWritableDatabase（）后应用程序崩溃

1 个答案: