public final class EvaluationException
extends java.lang.Exception
OperationEval.evaluate()
and Function.evaluate()
method signatures do not throw this exception so it cannot propagate outside.
Here is an example coded without EvaluationException
, to show how it can help:
public Eval evaluate(Eval[] args, int srcRow, short srcCol) {
// ...
Eval arg0 = args[0];
if(arg0 instanceof ErrorEval) {
return arg0;
}
if(!(arg0 instanceof AreaEval)) {
return ErrorEval.VALUE_INVALID;
}
double temp = 0;
AreaEval area = (AreaEval)arg0;
ValueEval[] values = area.getValues();
for (int i = 0; i < values.length; i++) {
ValueEval ve = values[i];
if(ve instanceof ErrorEval) {
return ve;
}
if(!(ve instanceof NumericValueEval)) {
return ErrorEval.VALUE_INVALID;
}
temp += ((NumericValueEval)ve).getNumberValue();
}
// ...
}
In this example, if any error is encountered while processing the arguments, an error is
returned immediately. This code is difficult to refactor due to all the points where errors
are returned.EvaluationException
allows the error returning code to be consolidated to one
place.
public Eval evaluate(Eval[] args, int srcRow, short srcCol) {
try {
// ...
AreaEval area = getAreaArg(args[0]);
double temp = sumValues(area.getValues());
// ...
} catch (EvaluationException e) {
return e.getErrorEval();
}
}
private static AreaEval getAreaArg(Eval arg0) throws EvaluationException {
if (arg0 instanceof ErrorEval) {
throw new EvaluationException((ErrorEval) arg0);
}
if (arg0 instanceof AreaEval) {
return (AreaEval) arg0;
}
throw EvaluationException.invalidValue();
}
private double sumValues(ValueEval[] values) throws EvaluationException {
double temp = 0;
for (int i = 0; i < values.length; i++) {
ValueEval ve = values[i];
if (ve instanceof ErrorEval) {
throw new EvaluationException((ErrorEval) ve);
}
if (!(ve instanceof NumericValueEval)) {
throw EvaluationException.invalidValue();
}
temp += ((NumericValueEval) ve).getNumberValue();
}
return temp;
}
It is not mandatory to use EvaluationException, doing so might give the following advantages:
Note - Only standard evaluation errors are represented by EvaluationException
(
i.e. conditions expected to be encountered when evaluating arbitrary Excel formulas). Conditions
that could never occur in an Excel spreadsheet should result in runtime exceptions. Care should
be taken to not translate any POI internal error into an Excel evaluation error code.
Constructor and Description |
---|
EvaluationException(ErrorEval errorEval) |
Modifier and Type | Method and Description |
---|---|
ErrorEval |
getErrorEval() |
static EvaluationException |
invalidRef()
#REF! - Illegal or deleted cell reference
|
static EvaluationException |
invalidValue()
#VALUE! - Wrong type of operand
|
static EvaluationException |
numberError()
#NUM! - Value range overflow
|
public EvaluationException(ErrorEval errorEval)
public static EvaluationException invalidValue()
public static EvaluationException invalidRef()
public static EvaluationException numberError()
public ErrorEval getErrorEval()
Copyright 2022 The Apache Software Foundation or its licensors, as applicable.