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Migration

Contains rules about migrating from one JDK version to another. Don’t use these rules directly, rather, use a wrapper ruleset such as migrating_to_13.xml.

ReplaceVectorWithList

Since: PMD 3.4

Priority: 3

Consider replacing Vector usages with the newer java.util.ArrayList if expensive thread-safe operations are not required.


//Type/ReferenceType/ClassOrInterfaceType[@Image='Vector']
 
    

Example(s):


public class Foo {
 void bar() {
    Vector v = new Vector();
 }
}

  

ReplaceHashtableWithMap

Since: PMD 3.4

Priority: 3

Consider replacing Hashtable usage with the newer java.util.Map if thread safety is not required.

    
//Type/ReferenceType/ClassOrInterfaceType[@Image='Hashtable']
     
        

Example(s):

    
public class Foo {
	void bar() {
		Hashtable h = new Hashtable();
	}
}
    
      

ReplaceEnumerationWithIterator

Since: PMD 3.4

Priority: 3

Consider replacing Enumeration usages with the newer java.util.Iterator

    
//ImplementsList/ClassOrInterfaceType[@Image='Enumeration']
     
        

Example(s):

    
public class Foo implements Enumeration {
    private int x = 42;
    public boolean hasMoreElements() {
        return true;
    }
    public Object nextElement() {
        return String.valueOf(i++);
    }
}
    
      

AvoidEnumAsIdentifier

Since: PMD 3.4

Priority: 2

Use of the term ‘enum’ will conflict with newer versions of Java since it is a reserved word.

                  
//VariableDeclaratorId[@Image='enum']
                  
              

Example(s):

  
public class A {
	public  class foo {
		String enum = "foo";
	}
}
  
      

AvoidAssertAsIdentifier

Since: PMD 3.4

Priority: 2

Use of the term ‘assert’ will conflict with newer versions of Java since it is a reserved word.

                  
//VariableDeclaratorId[@Image='assert']
                  
              

Example(s):

  
public class A {
	public  class foo {
		String assert = "foo";
	}
}
  
      

IntegerInstantiation

Since: PMD 3.5

Priority: 2

Calling new Integer() causes memory allocation that can be avoided by the static Integer.valueOf(). It makes use of an internal cache that recycles earlier instances making it more memory efficient.

                  
//PrimaryPrefix
 /AllocationExpression
  [not (ArrayDimsAndInits)
   and (ClassOrInterfaceType/@Image='Integer'
    or ClassOrInterfaceType/@Image='java.lang.Integer')]
                  
              

Example(s):

  
public class Foo {
	private Integer i = new Integer(0); // change to Integer i = Integer.valueOf(0);
}
   
      

ByteInstantiation

Since: PMD 4.0

Priority: 2

Calling new Byte() causes memory allocation that can be avoided by the static Byte.valueOf(). It makes use of an internal cache that recycles earlier instances making it more memory efficient.

          
//PrimaryPrefix/AllocationExpression
[not (ArrayDimsAndInits)
and (ClassOrInterfaceType/@Image='Byte'
or ClassOrInterfaceType/@Image='java.lang.Byte')]
          
          

Example(s):


public class Foo {
	private Byte i = new Byte(0); // change to Byte i =	Byte.valueOf(0);
}

     

ShortInstantiation

Since: PMD 4.0

Priority: 2

Calling new Short() causes memory allocation that can be avoided by the static Short.valueOf(). It makes use of an internal cache that recycles earlier instances making it more memory efficient.


//PrimaryPrefix
/AllocationExpression
[not (ArrayDimsAndInits)
and (ClassOrInterfaceType/@Image='Short'
or ClassOrInterfaceType/@Image='java.lang.Short')]

          

Example(s):


public class Foo {
	private Short i = new Short(0); // change to Short i = Short.valueOf(0);
}

          

LongInstantiation

Since: PMD 4.0

Priority: 2

Calling new Long() causes memory allocation that can be avoided by the static Long.valueOf(). It makes use of an internal cache that recycles earlier instances making it more memory efficient.


//PrimaryPrefix
/AllocationExpression
[not (ArrayDimsAndInits)
and (ClassOrInterfaceType/@Image='Long'
or ClassOrInterfaceType/@Image='java.lang.Long')]

    

Example(s):


public class Foo {
	private Long i = new Long(0); // change to Long i = Long.valueOf(0);
}

    

JUnit4TestShouldUseBeforeAnnotation

Since: PMD 4.0

Priority: 3

In JUnit 3, the setUp method was used to set up all data entities required in running tests. JUnit 4 skips the setUp method and executes all methods annotated with @Before before all tests


//CompilationUnit[not(ImportDeclaration/Name[starts-with(@Image, "org.testng")])]
//ClassOrInterfaceBodyDeclaration[MethodDeclaration/MethodDeclarator[@Image='setUp']]
[count(Annotation//Name[@Image='Before'])=0]

              

Example(s):


public class MyTest {
    public void setUp() {
        bad();
    }
}
public class MyTest2 {
    @Before public void setUp() {
        good();
    }
}

      

JUnit4TestShouldUseAfterAnnotation

Since: PMD 4.0

Priority: 3

In JUnit 3, the tearDown method was used to clean up all data entities required in running tests. JUnit 4 skips the tearDown method and executes all methods annotated with @After after running each test


//CompilationUnit[not(ImportDeclaration/Name[starts-with(@Image, "org.testng")])]
//ClassOrInterfaceBodyDeclaration[MethodDeclaration/MethodDeclarator[@Image='tearDown']]
[count(Annotation//Name[@Image='After'])=0]

              

Example(s):


public class MyTest {
    public void tearDown() {
        bad();
    }
}
public class MyTest2 {
    @After public void tearDown() {
        good();
    }
}

      

JUnit4TestShouldUseTestAnnotation

Since: PMD 4.0

Priority: 3

In JUnit 3, the framework executed all methods which started with the word test as a unit test. In JUnit 4, only methods annotated with the @Test annotation are executed.


//ClassOrInterfaceBodyDeclaration[MethodDeclaration[@Public='true']/MethodDeclarator[starts-with(@Image,'test')]]
[count(Annotation//Name[@Image='Test'])=0]

              

Example(s):


public class MyTest {
    public void testBad() {
        doSomething();
    }

	@Test
    public void testGood() {
        doSomething();
    }
}

      

JUnit4SuitesShouldUseSuiteAnnotation

Since: PMD 4.0

Priority: 3

In JUnit 3, test suites are indicated by the suite() method. In JUnit 4, suites are indicated through the @RunWith(Suite.class) annotation.


//ClassOrInterfaceBodyDeclaration[MethodDeclaration/MethodDeclarator[@Image='suite']]
[MethodDeclaration/ResultType/Type/ReferenceType/ClassOrInterfaceType[@Image='Test' or @Image = 'junit.framework.Test']]
[not(MethodDeclaration/Block//ClassOrInterfaceType[@Image='JUnit4TestAdapter'])]

              

Example(s):


public class BadExample extends TestCase{

    public static Test suite(){
    	return new Suite();
    }
}

@RunWith(Suite.class)
@SuiteClasses( { TestOne.class, TestTwo.class })
public class GoodTest {
}
      

JUnitUseExpected

Since: PMD 4.0

Priority: 3

In JUnit4, use the @Test(expected) annotation to denote tests that should throw exceptions.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.java.rule.migrating.JUnitUseExpectedRule

Example(s):


public class MyTest {
	@Test
    public void testBad() {
        try {
            doSomething();
            fail("should have thrown an exception");
        } catch (Exception e) {
        }
    }

	@Test(expected=Exception.class)
    public void testGood() {
        doSomething();
    }
}

      

This rule has the following properties:

Name Default Value Description
violationSuppressRegex Suppress violations with messages matching a regular expression
violationSuppressXPath Suppress violations on nodes which match a given relative XPath expression.