com.github.sevntu.checkstyle.checks.coding

Class UselessSuperCtorCallCheck

java.lang.Object

com.puppycrawl.tools.checkstyle.api.AutomaticBean

com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

com.puppycrawl.tools.checkstyle.api.AbstractCheck

com.github.sevntu.checkstyle.checks.coding.UselessSuperCtorCallCheck

All Implemented Interfaces:

com.puppycrawl.tools.checkstyle.api.Configurable, com.puppycrawl.tools.checkstyle.api.Contextualizable

public class UselessSuperCtorCallCheck
extends com.puppycrawl.tools.checkstyle.api.AbstractCheck

Checks for useless "super()" calls in ctors.

"super()" call could be considered by Check as "useless" in two cases:

Case 1. no-argument "super()" is called from class ctor if class is not derived, for example:

 
 class Dummy {
     Dummy() {
             super();
     }
 }
 
 

"super()" call is useless because class "Dummy" is not derived.

Case 2. no-argument "super()" is called without parameters from class ctor if class is derived, for example:

 
 class Derived extends Base {
     Derived() {
             super();
     }
 }
 
 

Java compiler automatically inserts a call to the no-args constructor of the superclass, so there is no need to call super ctor explicitly. Check has options "allowCallToNoArgsSuperCtor" and "allowCallToNoArgsSuperCtorIfMultiplePublicCtor" to adjust check behavior for such cases( see Check`s options description for details).

Check has following options:

"allowCallToNoArgsSuperCtor" - if this option set to true, Check will not generate violations when "super()" called inside derived class. This option defaults to "false". If for example this option set to "true", then Check will not generate violation for cases like following:

 
 class Base {
     public Base() {
     }
 }

 class Derived extends Base {
     public Derived() {
         super();
     }
 }
 
 

"allowCallToNoArgsSuperCtorIfMultiplePublicCtor" - if this option set to "true", then Check will not generate violation when "super()" called inside class ctor when class has multiple public ctors(however, setting this option to "true" will not prevent Check from logging violation if class does not extend anything). This option defaults to "false". This option may be useful for cases in which class`s ctors just forward its arguments to super ctors, thus removing "super()" in this case will make default ctors look not like others. For example:

 
 class Base {
     public Base() {
     }

     public Base(int i) {
     }
 }

 class Derived extends Base {
     public Derived() {
         super(); // this "super()" will not be considered useless if option is set to true,
                  // because "Derived" has multiple public ctors.
     }

     public Derived(int i) {
         super(i); // this "super()" will not be considered useless if option is set to true,
                   // because "Derived" has multiple public ctors.
     }
 }

 class NotDerived {
     public NotDerived() {
         super(); // this "super()" will be considered useless regardless of option value,
                  // because "NotDerived" does not extend anything.
     }
     public NotDerived(int i) {
         super(); // this "super()" will be considered useless regardless of option value,
                  // because "NotDerived" does not extend anything.
     }
 }
 
 

Checkstyle configuration example with options "allowCallToNoArgsSuperCtor" and "allowCallToNoArgsSuperCtorIfMultiplePublicCtor" set to true.

   <module name="UselessSuperCtorCallCheck">
     <property name="allowCallToNoArgsSuperCtor" value="true"/>
     <property name="allowCallToNoArgsSuperCtorIfMultiplePublicCtor" value="true"/>
   </module>
 

Since:

1.13.0

Author:

Zuy Alexey

Nested Class Summary

Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

com.puppycrawl.tools.checkstyle.api.AutomaticBean.OutputStreamOptions

Field Summary

Fields

Modifier and Type	Field and Description
static String	MSG_IN_NOT_DERIVED_CLASS Violation message key.
static String	MSG_WITHOUT_ARGS Violation message key.

Constructor Summary

Constructors

Constructor and Description
UselessSuperCtorCallCheck()

Method Summary

Modifier and Type	Method and Description
int[]	getAcceptableTokens()
int[]	getDefaultTokens()
int[]	getRequiredTokens()
void	setAllowCallToNoArgsSuperCtor(boolean aAllowCallToNoArgsSuperCtor) Sets flag to allowCallToNoArgsSuperCtor.
void	setAllowCallToNoArgsSuperCtorIfMultiplePublicCtor(boolean aAllowCall) Sets flag to allowCallToNoArgsSuperCtorIfMultiplePublicCtor.
void	visitToken(com.puppycrawl.tools.checkstyle.api.DetailAST aSuperCallNode)

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck

beginTree, clearMessages, destroy, finishTree, getFileContents, getLine, getLines, getMessages, getTabWidth, getTokenNames, init, isCommentNodesRequired, leaveToken, log, log, log, setFileContents, setTabWidth, setTokens

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

finishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverity

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

configure, contextualize, getConfiguration, setupChild

Methods inherited from class java.lang.Object

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

Field Detail

MSG_IN_NOT_DERIVED_CLASS

public static final String MSG_IN_NOT_DERIVED_CLASS

Violation message key.

See Also:

Constant Field Values

MSG_WITHOUT_ARGS

public static final String MSG_WITHOUT_ARGS

Violation message key.

See Also:

Constant Field Values

Constructor Detail

UselessSuperCtorCallCheck

public UselessSuperCtorCallCheck()

Method Detail

setAllowCallToNoArgsSuperCtor

public void setAllowCallToNoArgsSuperCtor(boolean aAllowCallToNoArgsSuperCtor)

Sets flag to allowCallToNoArgsSuperCtor.

Parameters:

aAllowCallToNoArgsSuperCtor - if true, check will allow super() calls without arguments

setAllowCallToNoArgsSuperCtorIfMultiplePublicCtor

public void setAllowCallToNoArgsSuperCtorIfMultiplePublicCtor(boolean aAllowCall)

Sets flag to allowCallToNoArgsSuperCtorIfMultiplePublicCtor.

Parameters:

aAllowCall - if true, check will allow super() calls without arguments if class has multiple public constructors

getDefaultTokens

public int[] getDefaultTokens()

Specified by:

getDefaultTokens in class com.puppycrawl.tools.checkstyle.api.AbstractCheck

getAcceptableTokens

public int[] getAcceptableTokens()

Specified by:

getAcceptableTokens in class com.puppycrawl.tools.checkstyle.api.AbstractCheck

getRequiredTokens

public int[] getRequiredTokens()

Specified by:

getRequiredTokens in class com.puppycrawl.tools.checkstyle.api.AbstractCheck

visitToken

public void visitToken(com.puppycrawl.tools.checkstyle.api.DetailAST aSuperCallNode)

Overrides:

visitToken in class com.puppycrawl.tools.checkstyle.api.AbstractCheck