These rules deal with different problems that can occur with finalizers.
Since: PMD 1.5
Priority: 3
Empty finalize methods serve no purpose and should be removed.
//MethodDeclaration[MethodDeclarator[@Image='finalize'][not(FormalParameters/*)]]
/Block[count(*)=0]
Example(s):
public class Foo {
protected void finalize() {}
}
Since: PMD 1.5
Priority: 3
If the finalize() is implemented, it should do something besides just calling super.finalize().
//MethodDeclaration[MethodDeclarator[@Image="finalize"][not(FormalParameters/*)]]
/Block[count(BlockStatement)=1]
/BlockStatement[
Statement/StatementExpression/PrimaryExpression
[./PrimaryPrefix[@SuperModifier='true']]
[./PrimarySuffix[@Image='finalize']]
]
Example(s):
protected void finalize() {
super.finalize();
}
Since: PMD 1.5
Priority: 3
Methods named finalize() should not have parameters. It is confusing and most likely an attempt to overload Object.finalize(). It will not be called by the VM.
//MethodDeclaration
/MethodDeclarator[@Image='finalize'][FormalParameters[count(*)>0]]
Example(s):
public class Foo {
// this is confusing and probably a bug
protected void finalize(int a) {
}
}
Since: PMD 1.5
Priority: 3
If the finalize() is implemented, its last action should be to call super.finalize.
//MethodDeclaration[MethodDeclarator[@Image='finalize'][not(FormalParameters/*)]]
/Block
/BlockStatement[last()]
[not(Statement/StatementExpression/PrimaryExpression
[./PrimaryPrefix[@SuperModifier='true']]
[./PrimarySuffix[@Image='finalize']]
)
]
[not(Statement/TryStatement/FinallyStatement
/Block/BlockStatement/Statement/StatementExpression/PrimaryExpression
[./PrimaryPrefix[@SuperModifier='true']]
[./PrimarySuffix[@Image='finalize']]
)
]
Example(s):
protected void finalize() {
something();
// neglected to call super.finalize()
}
Since: PMD 1.1
Priority: 3
When overriding the finalize(), the new method should be set as protected. If made public, other classes may invoke it at inappropriate times.
//MethodDeclaration[@Protected="false"]
/MethodDeclarator[@Image="finalize"]
[not(FormalParameters/*)]
Example(s):
public void finalize() {
// do something
}
Since: PMD 3.0
Priority: 3
The method Object.finalize() is called by the garbage collector on an object when garbage collection determines that there are no more references to the object. It should not be invoked by application logic.
This rule is defined by the following Java class: net.sourceforge.pmd.lang.java.rule.finalizers.AvoidCallingFinalizeRule
Example(s):
void foo() {
Bar b = new Bar();
b.finalize();
}
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. |