Import Statement Rules

These rules deal with different problems that can occur with a class' import statements.

DuplicateImports

Since: PMD 0.5

Avoid duplicate import statements.

This rule is defined by the following Java class: net.sourceforge.pmd.rules.imports.DuplicateImportsRule

Example:

                

import java.lang.String;
import java.lang.*;
public class Foo {}

    
            

DontImportJavaLang

Since: PMD 0.5

Avoid importing anything from the package 'java.lang'. These classes are automatically imported (JLS 7.5.3).

This rule is defined by the following Java class: net.sourceforge.pmd.rules.imports.DontImportJavaLang

Example:

                

// this is bad
import java.lang.String;
public class Foo {}

// --- in another source code file...

// this is bad
import java.lang.*;

public class Foo {}

    
            

UnusedImports

Since: PMD 1.0

Avoid unused import statements.

This rule is defined by the following Java class: net.sourceforge.pmd.rules.imports.UnusedImportsRule

Example:

                

// this is bad
import java.io.File;
public class Foo {}

    
            

ImportFromSamePackage

Since: PMD 1.02

No need to import a type that lives in the same package.

This rule is defined by the following Java class: net.sourceforge.pmd.rules.imports.ImportFromSamePackageRule

Example:

                
 
 package foo;
 import foo.Buz; // no need for this
 import foo.*; // or this
 public class Bar{}
 
     
            

TooManyStaticImports

Since: PMD 4.1

If you overuse the static import feature, it can make your program unreadable and unmaintainable, polluting its namespace with all the static members you import. Readers of your code (including you, a few months after you wrote it) will not know which class a static member comes from (Sun 1.5 Language Guide).

This rule is defined by the following XPath expression:

.[count(ImportDeclaration[@Static = 'true']) > $maximumStaticImports]
	             

Example:

                
import static Lennon;
import static Ringo;
import static George;
import static Paul;
import static Yoko; // Too much !
		  
            

This rule has the following properties:

NameDefault valueDescription
maximumStaticImports All static imports can be disallowed by setting this to 0