public class EqualsAvoidNullCheck extends Check
Checks that any combination of String literals with optional assignment is on the left side of an equals() comparison.
Rationale: Calling the equals() method on String literals will avoid a potential NullPointerException. Also, it is pretty common to see null check right before equals comparisons which is not necessary in the below example. For example:
String nullString = null;
nullString.equals("My_Sweet_String");
should be refactored to
String nullString = null;
"My_Sweet_String".equals(nullString);
Limitations: If the equals method is overridden or
a covariant equals method is defined and the implementation
is incorrect (where s.equals(t) does not return the same result
as t.equals(s)) then rearranging the called on object and
parameter may have unexpected results
Java's Autoboxing feature has an affect
on how this check is implemented. Pre Java 5 all IDENT + IDENT
object concatenations would not cause a NullPointerException even
if null. Those situations could have been included in this check.
They would simply act as if they surrounded by String.valueof()
which would concatenate the String null.
The following example will cause a NullPointerException as a result of what autoboxing does.
Integer i = null, j = null; String number = "5" number.equals(i + j);Since, it is difficult to determine what kind of Object is being concatenated all ident concatenation is considered unsafe.
DEFAULT_ERROR_SCORE, DEFAULT_INFO_SCORE, DEFAULT_WARNING_SCORE, mScoring, mViolationSize| コンストラクタと説明 |
|---|
EqualsAvoidNullCheck() |
| 修飾子とタイプ | メソッドと説明 |
|---|---|
int[] |
getDefaultTokens()
Returns the default token a check is interested in.
|
void |
setIgnoreEqualsIgnoreCase(boolean aNewValue)
Whether to ignore checking
String.equalsIgnoreCase(String). |
void |
visitToken(DetailAST aMethodCall)
Called to process a token.
|
beginTree, destroy, finishTree, getAcceptableTokens, getClassLoader, getFileContents, getLines, getRequiredTokens, getTabWidth, getTokenNames, init, leaveToken, log, log, setClassLoader, setFileContents, setMessages, setTabWidth, setTokenscalculateScore, getCustomMessages, getErrorScore, getId, getInfoScore, getMessageBundle, getScore, getScoring, getSeverity, getSeverityLevel, getWarningScore, log, setErrorScore, setId, setInfoScore, setScore, setScoring, setSeverity, setWarningScoreconfigure, contextualize, finishLocalSetup, getConfiguration, setupChildpublic int[] getDefaultTokens()
CheckgetDefaultTokens クラス内 CheckTokenTypespublic void visitToken(DetailAST aMethodCall)
CheckvisitToken クラス内 CheckaMethodCall - the token to processpublic void setIgnoreEqualsIgnoreCase(boolean aNewValue)
String.equalsIgnoreCase(String).aNewValue - whether to ignore checking
String.equalsIgnoreCase(String).Copyright © 2001-2013. All Rights Reserved.