EqualsHashCodeCheck.java
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com.puppycrawl.tools.checkstyle.checks.coding |
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Checkstyle |
View: Reasons, Metrics, Source Code
These are the metrics that contribute to the Enerjy Score for this file, ranked by impact. So the metrics listed at the top influence the score to a greater extent that the metrics listed at the bottom.
| Metric | Description | |
|---|---|---|
////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2007 Oliver Burn
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
////////////////////////////////////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.coding;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import antlr.collections.AST;
import com.puppycrawl.tools.checkstyle.api.Check;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
/**
* <p>
* Checks that classes that override equals() also override hashCode().
* </p>
* <p>
* Rationale: The contract of equals() and hashCode() requires that
* equal objects have the same hashCode. Hence, whenever you override
* equals() you must override hashCode() to ensure that your class can
* be used in collections that are hash based.
* </p>
* <p>
* An example of how to configure the check is:
* </p>
* <pre>
* <module name="EqualsHashCode"/>
* </pre>
* @author lkuehne
*/
public class EqualsHashCodeCheck
extends Check
{
// implementation note: we have to use the following members to
// keep track of definitions in different inner classes
/** maps OBJ_BLOCK to the method definition of equals() */
private final Map mObjBlockEquals = new HashMap();
/** the set of OBJ_BLOCKs that contain a definition of hashCode() */
private final Set mObjBlockWithHashCode = new HashSet();
/** {@inheritDoc} */
public int[] getDefaultTokens()
{
return new int[] {TokenTypes.METHOD_DEF};
}
/** {@inheritDoc} */
public void beginTree(DetailAST aRootAST)
{
mObjBlockEquals.clear();
mObjBlockWithHashCode.clear();
}
/** {@inheritDoc} */
public void visitToken(DetailAST aAST)
{
final DetailAST modifiers = (DetailAST) aAST.getFirstChild();
final AST type = aAST.findFirstToken(TokenTypes.TYPE);
final AST methodName = aAST.findFirstToken(TokenTypes.IDENT);
final DetailAST parameters = aAST.findFirstToken(TokenTypes.PARAMETERS);
if ((type.getFirstChild().getType() == TokenTypes.LITERAL_BOOLEAN)
&& "equals".equals(methodName.getText())
&& modifiers.branchContains(TokenTypes.LITERAL_PUBLIC)
&& (parameters.getChildCount() == 1)
&& isObjectParam(parameters.getFirstChild())
)
{
mObjBlockEquals.put(aAST.getParent(), aAST);
}
else if ((type.getFirstChild().getType() == TokenTypes.LITERAL_INT)
&& "hashCode".equals(methodName.getText())
&& modifiers.branchContains(TokenTypes.LITERAL_PUBLIC)
&& (parameters.getFirstChild() == null)) // no params
{
mObjBlockWithHashCode.add(aAST.getParent());
}
}
/**
* Determines if an AST is a formal param of type Object (or subclass).
* @param aFirstChild the AST to check
* @return true iff aFirstChild is a parameter of an Object type.
*/
private boolean isObjectParam(AST aFirstChild)
{
final AST modifiers = aFirstChild.getFirstChild();
final AST type = modifiers.getNextSibling();
switch (type.getFirstChild().getType()) {
case TokenTypes.LITERAL_BOOLEAN:
case TokenTypes.LITERAL_BYTE:
case TokenTypes.LITERAL_CHAR:
case TokenTypes.LITERAL_DOUBLE:
case TokenTypes.LITERAL_FLOAT:
case TokenTypes.LITERAL_INT:
case TokenTypes.LITERAL_LONG:
case TokenTypes.LITERAL_SHORT:
return false;
default:
return true;
}
}
/**
* {@inheritDoc}
*/
public void finishTree(DetailAST aRootAST)
{
final Set equalsDefs = mObjBlockEquals.keySet();
for (final Iterator it = equalsDefs.iterator(); it.hasNext();) {
final Object objBlock = it.next();
if (!mObjBlockWithHashCode.contains(objBlock)) {
final DetailAST equalsAST =
(DetailAST) mObjBlockEquals.get(objBlock);
log(equalsAST.getLineNo(), equalsAST.getColumnNo(),
"equals.noHashCode");
}
}
mObjBlockEquals.clear();
mObjBlockWithHashCode.clear();
}
}
The table below shows all metrics for EqualsHashCodeCheck.java.
| Metric | Value | Description | |
|---|---|---|---|