edu.umd.cs.findbugs.ba.npe

Class IsNullValue

public class IsNullValue extends Object implements IsNullValueAnalysisFeatures, Debug

A class to abstractly represent values in stack slots, indicating whether thoses values can be null, non-null, null on some incoming path, or unknown.

Author: David Hovemeyer

Method Summary
static IsNullValue	checkedNonNullValue() Get the instance representing a value known to be non-null because it was compared against null value, or because we saw the object creation.
static IsNullValue	checkedNullValue() Get the instance representing a value known to be null because it was compared against null value, or because we saw that it was assigned the null constant.
IsNullValue	downgradeOnControlSplit() Control split: move given value down in the lattice if it is a conditionally-null value.
Location	getLocationOfKaBoom()
boolean	isChecked() Is this value known because of an explicit null check?
boolean	isDefinitelyNotNull() Is this value definitely not null?
boolean	isDefinitelyNull() Is this value definitely null?
boolean	isException() Was this value propagated on an exception path?
boolean	isFieldValue()
boolean	isNullOnComplicatedPath() Is this value null on a complicated path?
boolean	isNullOnSomePath() Is this value null on some path?
boolean	isParamValue() Was this value marked as a possibly null parameter?
boolean	isReturnValue() Was this value marked as a possibly null return value?
IsNullValue	markInformationAsComingFromFieldValue(XField field) Convert to a value known because it was returned from a method in a method property database.
IsNullValue	markInformationAsComingFromReturnValueOfMethod(XMethod methodInvoked) Convert to a value known because it was returned from a method in a method property database.
static IsNullValue	merge(IsNullValue a, IsNullValue b) Merge two values.
boolean	mightBeNull() Return true if this value is either definitely null, or might be null on a simple path.
static IsNullValue	noKaboomNonNullValue(Location ins) Get the instance representing a value known to be non-null because a NPE would have occurred if it were null.
static IsNullValue	nonNullValue() Get the instance representing values that are definitely not null.
static IsNullValue	nonReportingNotNullValue() Get non-reporting non-null value.
static IsNullValue	nullOnComplexPathValue() Get null on complex path value.
static IsNullValue	nullOnComplexPathValue3() Like "null on complex path" except that there are at least three branches between the explicit null value and the current location.
static IsNullValue	nullOnSimplePathValue() Get the instance representing values that are definitely null on some simple (no branches) incoming path.
static IsNullValue	nullValue() Get the instance representing values that are definitely null.
static IsNullValue	parameterMarkedAsMightBeNull(XMethodParameter mp) Get instance representing a parameter marked as MightBeNull
static IsNullValue	pathSensitiveNonNullValue() Get non-null value resulting from comparison to explicit null.
static IsNullValue	pathSensitiveNullValue() Get null value resulting from comparison to explicit null.
IsNullValue	toExceptionValue() Convert to an exception path value.
boolean	wouldHaveBeenAKaboom() Is this value known to be non null because a NPE would have occurred otherwise?

Method Detail

checkedNonNullValue

public static IsNullValue checkedNonNullValue()

Get the instance representing a value known to be non-null because it was compared against null value, or because we saw the object creation.

checkedNullValue

public static IsNullValue checkedNullValue()

Get the instance representing a value known to be null because it was compared against null value, or because we saw that it was assigned the null constant.

downgradeOnControlSplit

public IsNullValue downgradeOnControlSplit()

Control split: move given value down in the lattice if it is a conditionally-null value.

Returns: another value (equal or further down in the lattice)

isChecked

public boolean isChecked()

Is this value known because of an explicit null check?

isDefinitelyNotNull

public boolean isDefinitelyNotNull()

Is this value definitely not null?

isDefinitelyNull

public boolean isDefinitelyNull()

Is this value definitely null?

isException

public boolean isException()

Was this value propagated on an exception path?

isNullOnComplicatedPath

public boolean isNullOnComplicatedPath()

Is this value null on a complicated path?

isNullOnSomePath

public boolean isNullOnSomePath()

Is this value null on some path?

isParamValue

public boolean isParamValue()

Was this value marked as a possibly null parameter?

isReturnValue

public boolean isReturnValue()

Was this value marked as a possibly null return value?

markInformationAsComingFromFieldValue

public IsNullValue markInformationAsComingFromFieldValue(XField field)

Convert to a value known because it was returned from a method in a method property database.

Parameters: methodInvoked TODO

markInformationAsComingFromReturnValueOfMethod

public IsNullValue markInformationAsComingFromReturnValueOfMethod(XMethod methodInvoked)

Convert to a value known because it was returned from a method in a method property database.

Parameters: methodInvoked TODO

merge

public static IsNullValue merge(IsNullValue a, IsNullValue b)

Merge two values.

mightBeNull

public boolean mightBeNull()

Return true if this value is either definitely null, or might be null on a simple path.

Returns: true if this value is either definitely null, or might be null on a simple path, false otherwise

noKaboomNonNullValue

public static IsNullValue noKaboomNonNullValue(Location ins)

Get the instance representing a value known to be non-null because a NPE would have occurred if it were null.

nonNullValue

public static IsNullValue nonNullValue()

Get the instance representing values that are definitely not null.

nonReportingNotNullValue

public static IsNullValue nonReportingNotNullValue()

Get non-reporting non-null value. This is what we use for unknown values.

nullOnComplexPathValue

public static IsNullValue nullOnComplexPathValue()

Get null on complex path value. This is like null on simple path value, but there are at least two branches between the explicit null value and the current location. If the conditions are correlated, then the path on which the value is null may be infeasible.