001//////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code for adherence to a set of rules. 003// Copyright (C) 2001-2014 Oliver Burn 004// 005// This library is free software; you can redistribute it and/or 006// modify it under the terms of the GNU Lesser General Public 007// License as published by the Free Software Foundation; either 008// version 2.1 of the License, or (at your option) any later version. 009// 010// This library is distributed in the hope that it will be useful, 011// but WITHOUT ANY WARRANTY; without even the implied warranty of 012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 013// Lesser General Public License for more details. 014// 015// You should have received a copy of the GNU Lesser General Public 016// License along with this library; if not, write to the Free Software 017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 018//////////////////////////////////////////////////////////////////////////////// 019 020package com.puppycrawl.tools.checkstyle.checks.imports; 021 022import com.google.common.collect.Sets; 023import com.puppycrawl.tools.checkstyle.api.Check; 024import com.puppycrawl.tools.checkstyle.api.DetailAST; 025import com.puppycrawl.tools.checkstyle.api.FullIdent; 026import com.puppycrawl.tools.checkstyle.api.TokenTypes; 027import java.util.Set; 028 029/** 030 * <p> 031 * Checks for imports that are redundant. An import statement is 032 * considered redundant if: 033 * </p> 034 *<ul> 035 * <li>It is a duplicate of another import. This is, when a class is imported 036 * more than once.</li> 037 * <li>The class non-statically imported is from the <code>java.lang</code> 038 * package. For example importing <code>java.lang.String</code>.</li> 039 * <li>The class non-statically imported is from the same package as the 040 * current package.</li> 041 *</ul> 042 * <p> 043 * An example of how to configure the check is: 044 * </p> 045 * <pre> 046 * <module name="RedundantImport"/> 047 * </pre> 048 * 049 * Compatible with Java 1.5 source. 050 * 051 * @author Oliver Burn 052 * @version 1.0 053 */ 054public class RedundantImportCheck 055 extends Check 056{ 057 /** name of package in file */ 058 private String mPkgName; 059 /** set of the imports */ 060 private final Set<FullIdent> mImports = Sets.newHashSet(); 061 /** set of static imports */ 062 private final Set<FullIdent> mStaticImports = Sets.newHashSet(); 063 064 @Override 065 public void beginTree(DetailAST aRootAST) 066 { 067 mPkgName = null; 068 mImports.clear(); 069 mStaticImports.clear(); 070 } 071 072 @Override 073 public int[] getDefaultTokens() 074 { 075 return new int[] 076 {TokenTypes.IMPORT, 077 TokenTypes.STATIC_IMPORT, 078 TokenTypes.PACKAGE_DEF, }; 079 } 080 081 @Override 082 public void visitToken(DetailAST aAST) 083 { 084 if (aAST.getType() == TokenTypes.PACKAGE_DEF) { 085 mPkgName = FullIdent.createFullIdent( 086 aAST.getLastChild().getPreviousSibling()).getText(); 087 } 088 else if (aAST.getType() == TokenTypes.IMPORT) { 089 final FullIdent imp = FullIdent.createFullIdentBelow(aAST); 090 if (fromPackage(imp.getText(), "java.lang")) { 091 log(aAST.getLineNo(), aAST.getColumnNo(), "import.lang", 092 imp.getText()); 093 } 094 else if (fromPackage(imp.getText(), mPkgName)) { 095 log(aAST.getLineNo(), aAST.getColumnNo(), "import.same", 096 imp.getText()); 097 } 098 // Check for a duplicate import 099 for (FullIdent full : mImports) { 100 if (imp.getText().equals(full.getText())) { 101 log(aAST.getLineNo(), aAST.getColumnNo(), 102 "import.duplicate", full.getLineNo(), 103 imp.getText()); 104 } 105 } 106 107 mImports.add(imp); 108 } 109 else { 110 // Check for a duplicate static import 111 final FullIdent imp = 112 FullIdent.createFullIdent( 113 aAST.getLastChild().getPreviousSibling()); 114 for (FullIdent full : mStaticImports) { 115 if (imp.getText().equals(full.getText())) { 116 log(aAST.getLineNo(), aAST.getColumnNo(), 117 "import.duplicate", full.getLineNo(), imp.getText()); 118 } 119 } 120 121 mStaticImports.add(imp); 122 } 123 } 124 125 /** 126 * Determines if an import statement is for types from a specified package. 127 * @param aImport the import name 128 * @param aPkg the package name 129 * @return whether from the package 130 */ 131 private static boolean fromPackage(String aImport, String aPkg) 132 { 133 boolean retVal = false; 134 if (aPkg == null) { 135 // If not package, then check for no package in the import. 136 retVal = (aImport.indexOf('.') == -1); 137 } 138 else { 139 final int index = aImport.lastIndexOf('.'); 140 if (index != -1) { 141 final String front = aImport.substring(0, index); 142 retVal = front.equals(aPkg); 143 } 144 } 145 return retVal; 146 } 147}