question: private void changeColumnsType ( List < ColumnModel > columnModelList ) { LogUtil . d ( TAG , "do changeColumnsType" ) ; List < String > columnNames = new ArrayList < String > ( ) ; if ( columnModelList != null && ! columnModelList . isEmpty ( ) ) { for ( ColumnModel columnModel : columnModelList ) { columnNames . add ( columnModel . getColumnName ( ) ) ; } } removeColumns ( columnNames ) ; addColumns ( columnModelList ) ; }
target:  When some fields type are changed in class, the table should drop the before columns and create new columns with same name but new types.