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////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2015 the original author or authors.
//
// 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 antlr.collections.AST;

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

/**
 * 

Checks that string literals are not used with * {@code ==} or {@code !=}. *

*

* Rationale: Novice Java programmers often use code like * {@code if (x == "something")} when they mean * {@code if ("something".equals(x))}. *

* * @author Lars Kühne */ public class StringLiteralEqualityCheck extends Check { /** * A key is pointing to the warning message text in "messages.properties" * file. */ public static final String MSG_KEY = "string.literal.equality"; @Override public int[] getDefaultTokens() { return getAcceptableTokens(); } @Override public int[] getAcceptableTokens() { return new int[] {TokenTypes.EQUAL, TokenTypes.NOT_EQUAL}; } @Override public int[] getRequiredTokens() { return getAcceptableTokens(); } @Override public void visitToken(DetailAST ast) { // no need to check for nulls here, == and != always have two children final AST firstChild = ast.getFirstChild(); final AST secondChild = firstChild.getNextSibling(); if (firstChild.getType() == TokenTypes.STRING_LITERAL || secondChild.getType() == TokenTypes.STRING_LITERAL) { log(ast.getLineNo(), ast.getColumnNo(), MSG_KEY, ast.getText()); } } }




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