question: private List < ColumnModel > findColumnsToAdd ( ) { List < ColumnModel > columnsToAdd = new ArrayList < ColumnModel > ( ) ; for ( ColumnModel columnModel : mTableModel . getColumnModels ( ) ) { String columnName = columnModel . getColumnName ( ) ; if ( ! mTableModelDB . containsColumn ( columnName ) ) { columnsToAdd . add ( columnModel ) ; } } return columnsToAdd ; }
target:  It will find the difference between class model and table model. If there's a field in the class without a corresponding column in the table, this field is a new added column. This method find all new added columns.