Migration Rules

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

Consider replacing Vector usages with the newer java.util.ArrayList if expensive threadsafe operation is not required.

This rule is defined by the following XPath expression:


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

Example:

                

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

  
            

ReplaceHashtableWithMap

Since: PMD 3.4

Consider replacing this Hashtable with the newer java.util.Map

This rule is defined by the following XPath expression:

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

Example:

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

ReplaceEnumerationWithIterator

Since: PMD 3.4

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

This rule is defined by the following XPath expression:

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

Example:

                
    
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

Finds all places where 'enum' is used as an identifier.

This rule is defined by the following XPath expression:

                  
//VariableDeclaratorId[@Image='enum']
                  
              

Example:

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

AvoidAssertAsIdentifier

Since: PMD 3.4

Finds all places where 'assert' is used as an identifier.

This rule is defined by the following XPath expression:

                  
//VariableDeclaratorId[@Image='assert']
                  
              

Example:

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

IntegerInstantiation

Since: PMD 3.5

In JDK 1.5, calling new Integer() causes memory allocation. Integer.valueOf() is more memory friendly.

This rule is defined by the following XPath expression:

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

Example:

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

ByteInstantiation

Since: PMD 4.0

In JDK 1.5, calling new Byte() causes memory allocation. Byte.valueOf() is more memory friendly.

This rule is defined by the following XPath expression:

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

Example:

                

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

     
            

ShortInstantiation

Since: PMD 4.0

In JDK 1.5, calling new Short() causes memory allocation. Short.valueOf() is more memory friendly.

This rule is defined by the following XPath expression:


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

          

Example:

                

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

          
            

LongInstantiation

Since: PMD 4.0

In JDK 1.5, calling new Long() causes memory allocation. Long.valueOf() is more memory friendly.

This rule is defined by the following XPath expression:


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

    

Example:

                

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

    
            

JUnit4TestShouldUseBeforeAnnotation

Since: PMD 4.0

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

This rule is defined by the following XPath expression:


//ClassOrInterfaceBodyDeclaration[MethodDeclaration/MethodDeclarator[@Image='setUp']]
[count(Annotation/MarkerAnnotation/Name[@Image='Before'])=0]

              

Example:

                

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

      
            

JUnit4TestShouldUseAfterAnnotation

Since: PMD 4.0

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

This rule is defined by the following XPath expression:


//ClassOrInterfaceBodyDeclaration[MethodDeclaration/MethodDeclarator[@Image='tearDown']]
[count(Annotation/MarkerAnnotation/Name[@Image='After'])=0]

              

Example:

                

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

      
            

JUnit4TestShouldUseTestAnnotation

Since: PMD 4.0

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.

This rule is defined by the following XPath expression:


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

              

Example:

                

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

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

      
            

JUnit4SuitesShouldUseSuiteAnnotation

Since: PMD 4.0

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

This rule is defined by the following XPath expression:


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

              

Example:

                

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

This rule is defined by the following Java class: net.sourceforge.pmd.rules.migration.JUnitUseExpected

Example:

                

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();
    }
}