com.puppycrawl.tools.checkstyle.checks.coding.StringLiteralEqualityCheck Maven / Gradle / Ivy
////////////////////////////////////////////////////////////////////////////////
// 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());
}
}
}