DBHelp
public class DbHelper extends SQLiteOpenHelper {
private final static String DB_NAME = "HKC";
public DbHelper(Context context) {
super(context, DB_NAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
//创建了一个名为person的表
String sql = "CREATE TABLE product_info(_id INTEGER PRIMARY KEY AUTOINCREMENT," +
"iccid varchar(10)," +
"name varchar(50)," +
"directions varchar(100)," +
"type varchar(1)," +
"price varchar(10)," +
"old_price varchar(10))";
db.execSQL(sql);
Log.d("SQLiteDatabaseTest", sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
MainActivity 代码
public class MainActivity extends Activity {
private static final String TAG = "MainActivity";
DbHelper dbHelper=new DbHelper(this);
SQLiteDatabase db=dbHelper.getWritableDatabase();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void onClick(View view) {
switch (view.getId()) {
case R.id.insert:
break;
case R.id.select:
break;
}
}
}
异常
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.sqlite.SQLiteDatabase android.content.Context.openOrCreateDatabase(java.lang.String, int, android.database.sqlite.SQLiteDatabase$CursorFactory, android.database.DatabaseErrorHandler)' on a null object reference
