////////////////////////////////////////////////////////////////////////////////

 // checkstyle: Checks Java source code for adherence to a set of rules.

 // Copyright (C) 2001-2014  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 com.puppycrawl.tools.checkstyle.api.Check;

 import com.puppycrawl.tools.checkstyle.api.TokenTypes;

 import com.puppycrawl.tools.checkstyle.api.DetailAST;

 import antlr.collections.AST;

 /**

  * <p>Checks that string literals are not used with

  * <code>==</code> or <code>&#33;=</code>.

  * </p>

  * <p>

  * Rationale: Novice Java programmers often use code like

  * <code>if (x == &quot;something&quot;)</code> when they mean

  * <code>if (&quot;something&quot;.equals(x))</code>.

  * </p>

  *

  * @author Lars Kühne

  */

 public class StringLiteralEqualityCheck extends Check

 {

     @Override

     public int[] getDefaultTokens()

     {

         return new int[] {TokenTypes.EQUAL, TokenTypes.NOT_EQUAL};

     }

     @Override

     public void visitToken(DetailAST aAST)

     {

         // no need to check for nulls here, == and != always have two children

         final AST firstChild = aAST.getFirstChild();

         final AST secondChild = firstChild.getNextSibling();

         if ((firstChild.getType() == TokenTypes.STRING_LITERAL)

                 || (secondChild.getType() == TokenTypes.STRING_LITERAL))

         {

             log(aAST.getLineNo(), aAST.getColumnNo(),

                     "string.literal.equality", aAST.getText());

         }

     }

 }