Package edu.umd.cs.findbugs.detect

Class NoiseNullDeref

java.lang.Object

edu.umd.cs.findbugs.detect.NoiseNullDeref

All Implemented Interfaces:

NullDerefAndRedundantComparisonCollector, Detector, Priorities, UseAnnotationDatabase

public class NoiseNullDeref
extends Object
implements Detector, UseAnnotationDatabase, NullDerefAndRedundantComparisonCollector

A Detector to find instructions where a NullPointerException might be raised. We also look for useless reference comparisons involving null and non-null values.

Author:

David Hovemeyer, William Pugh

See Also:

• IsNullValueAnalysis

Field Summary

Fields

Modifier and Type	Field	Description
static final boolean	DEBUG

Fields inherited from interface edu.umd.cs.findbugs.Priorities

EXP_PRIORITY, HIGH_PRIORITY, IGNORE_PRIORITY, LOW_PRIORITY, NORMAL_PRIORITY

Constructor Summary

Constructors

Constructor	Description
NoiseNullDeref(BugReporter bugReporter)

Method Summary

Modifier and Type	Method	Description
void	foundGuaranteedNullDeref(Set<Location> assignedNullLocationSet, Set<Location> derefLocationSet, SortedSet<Location> doomedLocations, ValueNumberDataflow vna, ValueNumber refValue, BugAnnotation variableAnnotation, NullValueUnconditionalDeref deref, boolean npeIfStatementCovered)	Subclasses should override this method to capture values assigned null (or that become null through a comparison and branch) that are guaranteed to reach a dereference (ignoring implicit exception paths).
void	foundNullDeref(Location location, ValueNumber valueNumber, IsNullValue refValue, ValueNumberFrame vnaFrame)	Deprecated. Use foundNullDeref(Location,ValueNumber,IsNullValue,ValueNumberFrame,boolean) instead
void	foundNullDeref(Location location, ValueNumber valueNumber, IsNullValue refValue, ValueNumberFrame vnaFrame, boolean isConsistent)	Subclasses should override this method to capture locations where a null pointer is dereferenced.
void	foundRedundantNullCheck(Location location, RedundantBranch redundantBranch)	Subclasses should override this method to capture locations where a redundant null comparison is performed.
static boolean	isThrower(BasicBlock target)
void	report()	This method is called after all classes to be visited.
boolean	skipIfInsideCatchNull()
void	visitClassContext(ClassContext classContext)	Visit the ClassContext for a class which should be analyzed for instances of bug patterns.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

DEBUG

public static final boolean DEBUG

Constructor Details

NoiseNullDeref

public NoiseNullDeref(BugReporter bugReporter)

Method Details

visitClassContext

public void visitClassContext(ClassContext classContext)

Description copied from interface: Detector

Visit the ClassContext for a class which should be analyzed for instances of bug patterns.

Specified by:

visitClassContext in interface Detector

Parameters:

classContext - the ClassContext

report

public void report()

Description copied from interface: Detector

This method is called after all classes to be visited. It should be used by any detectors which accumulate information over all visited classes to generate results.

Specified by:

report in interface Detector

skipIfInsideCatchNull

public boolean skipIfInsideCatchNull()

foundNullDeref

@Deprecated
public void foundNullDeref(Location location,
 ValueNumber valueNumber,
 IsNullValue refValue,
 ValueNumberFrame vnaFrame)

Deprecated.

Use foundNullDeref(Location,ValueNumber,IsNullValue,ValueNumberFrame,boolean) instead

Description copied from interface: NullDerefAndRedundantComparisonCollector

Subclasses should override this method to capture locations where a null pointer is dereferenced.

Specified by:

foundNullDeref in interface NullDerefAndRedundantComparisonCollector

Parameters:

location - the Location of the null dereference

valueNumber - the ValueNumber of the possibly-null value

refValue - the kind of possibly-null value dereferenced

vnaFrame - The ValueNumber Frame at the point where the dereference occurred

foundNullDeref

public void foundNullDeref(Location location,
 ValueNumber valueNumber,
 IsNullValue refValue,
 ValueNumberFrame vnaFrame,
 boolean isConsistent)

Description copied from interface: NullDerefAndRedundantComparisonCollector

Subclasses should override this method to capture locations where a null pointer is dereferenced.

Specified by:

foundNullDeref in interface NullDerefAndRedundantComparisonCollector

Parameters:

location - the Location of the null dereference

valueNumber - the ValueNumber of the possibly-null value

refValue - the kind of possibly-null value dereferenced

vnaFrame - The ValueNumber Frame at the point where the dereference occurred

isConsistent - true if the refValue is identical at all clones of the same instruction

isThrower

public static boolean isThrower(BasicBlock target)

foundRedundantNullCheck

public void foundRedundantNullCheck(Location location,
 RedundantBranch redundantBranch)

Description copied from interface: NullDerefAndRedundantComparisonCollector

Subclasses should override this method to capture locations where a redundant null comparison is performed.

Specified by:

foundRedundantNullCheck in interface NullDerefAndRedundantComparisonCollector

Parameters:

location - the Location of the redundant null check

redundantBranch - the RedundantBranch

foundGuaranteedNullDeref

public void foundGuaranteedNullDeref(@Nonnull
 Set<Location> assignedNullLocationSet,
 @Nonnull
 Set<Location> derefLocationSet,
 SortedSet<Location> doomedLocations,
 ValueNumberDataflow vna,
 ValueNumber refValue,
 @CheckForNull
 BugAnnotation variableAnnotation,
 NullValueUnconditionalDeref deref,
 boolean npeIfStatementCovered)

Description copied from interface: NullDerefAndRedundantComparisonCollector

Subclasses should override this method to capture values assigned null (or that become null through a comparison and branch) that are guaranteed to reach a dereference (ignoring implicit exception paths).

Specified by:

foundGuaranteedNullDeref in interface NullDerefAndRedundantComparisonCollector

Parameters:

assignedNullLocationSet - set of locations where the value becomes null

derefLocationSet - set of locations where dereferences occur

doomedLocations - locations at which the value is doomed

vna - ValueNumberDataflow

refValue - the null value

variableAnnotation - TODO

deref - TODO

npeIfStatementCovered - true if doom location is a statement