AvoidStarImport

Since Checkstyle 3.0

Description

Checks that there are no import statements that use the * notation.

Rationale: Importing all classes from a package or static members from a class leads to tight coupling between packages or classes and might lead to problems when a new version of a library introduces name clashes.

Notes

Note that property excludes is not recursive, subpackages of excluded packages are not automatically excluded.

Properties

name description type default value since
allowClassImports Control whether to allow starred class imports like import java.util.*;. boolean false 5.3
allowStaticMemberImports Control whether to allow starred static member imports like import static org.junit.Assert.*;. boolean false 5.3
excludes Specify packages where starred class imports are allowed and classes where starred static member imports are allowed. String[] {} 3.2

Examples

To configure the check: 

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidStarImport"/>
  </module>
</module>

Example: 

import java.util.Scanner;
import java.io.*;                 // violation
import static java.lang.Math.*;   // violation
import java.util.*;               // violation
import java.net.*;                // violation

To configure the check so that star imports from packages java.io and java.net as well as static members from class java.lang.Math are allowed: 

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidStarImport">
      <property name="excludes" value="java.io,java.net,java.lang.Math"/>
    </module>
  </module>
</module>

Example: 

import java.util.Scanner;
import java.io.*;
import static java.lang.Math.*;
import java.util.*;               // violation
import java.net.*;

To configure the check so that star imports from all packages are allowed: 

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidStarImport">
      <property name="allowClassImports" value="true"/>
    </module>
  </module>
</module>

Example: 

import java.util.Scanner;
import java.io.*;
import static java.lang.Math.*;   // violation
import java.util.*;
import java.net.*;

To configure the check so that starred static member imports from all packages are allowed: 

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidStarImport">
      <property name="allowStaticMemberImports" value="true"/>
    </module>
  </module>
</module>

Example: 

import java.util.Scanner;
import java.io.*;                 // violation
import static java.lang.Math.*;
import java.util.*;               // violation
import java.net.*;                // violation

To configure the check so that star imports from packages java.io and java.net are allowed: 

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidStarImport">
      <property name="allowClassImports" value="true"/>
      <property name="excludes" value="java.io,java.net"/>
    </module>
  </module>
</module>

Example: 

import java.util.Scanner;
import java.io.*;
import static java.lang.Math.*;   // violation
import java.util.*;
import java.net.*;

To configure the check so that star imports from packages java.io and java.net as well as static members imports from all packages are allowed: 

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidStarImport">
      <property name="allowStaticMemberImports" value="true"/>
      <property name="excludes" value="java.io,java.net"/>
    </module>
  </module>
</module>

Example: 

import java.util.Scanner;
import java.io.*;
import static java.lang.Math.*;
import java.util.*;               // violation
import java.net.*;

Example of Usage

Violation Messages

All messages can be customized if the default message doesn't suit you. Please see the documentation to learn how to.

Package

com.puppycrawl.tools.checkstyle.checks.imports

Parent Module

TreeWalker