If the value of a variable is null, then it is, of course, illegal to refer to instance variables or instance methods through that variable -- since there is no object, and hence no instance variables to refer to! For example, if the value of the variable std is null, then it would be illegal to refer to std.test1.n this picture, when a variable contains a reference to an object, the value of that variable is shown as an arrow pointing to the object. Note, by the way, that the Strings are objects! The variable std3, with a value of null, doesn't point anywhere.
Mitochondrial disease is a group of disorders caused by dysfunctional mitochondria, the organelles that generate energy for the cell.itochondrial diseases are sometimes (about 15% of the time) caused by mutations in the mitochondrial DNA that affect mitochondrial function.
Review the available Assessment Questionnaires for the symptoms of Mitochondrial diseases: 1  Muscle weakness -- Assessment Questionnaire. 2  Muscle cramping -- Assessment Questionnaire. 3  Dementia -- Assessment Questionnaire. 4  Deafness -- Assessment Questionnaire. 5  Blindness -- Assessment Questionnaire. 6  Nausea -- Assessment Questionnaire.