Since Checkstyle 3.0
Checks the number of parameters of a method or constructor.
| name | description | type | default value | since |
|---|---|---|---|---|
| ignoreAnnotatedBy | Ignore methods and constructors annotated with the specified annotation(s). | String[] | {} |
10.15.0 |
| ignoreOverriddenMethods | Ignore number of parameters for methods with @Override annotation. |
boolean | false |
6.2 |
| max | Specify the maximum number of parameters allowed. | int | 7 |
3.0 |
| tokens | tokens to check | subset of tokens METHOD_DEF , CTOR_DEF . | METHOD_DEF , CTOR_DEF . | 3.0 |
To configure the check:
<module name="Checker">
<module name="TreeWalker">
<module name="ParameterNumber"/>
</module>
</module>
Example:
class Example1 extends ExternalService1 {
@JsonCreator
// violation below, 'More than 7 parameters (found 8)'
Example1(int a, int b, int c, int d,
int e, int f, int g, int h) {}
// violation below, 'More than 7 parameters (found 8)'
Example1(String a, String b, String c, String d,
String e, String f, String g, String h) {}
@Override
// violation below, 'More than 7 parameters (found 8)'
public void processData(String a, String b, String c, String d,
String e, String f, String g, String h) {}
}
class ExternalService1 {
// violation below, 'More than 7 parameters (found 8)'
public void processData(String a, String b, String c, String d,
String e, String f, String g, String h) {}
}
To configure the check to allow 10 parameters for a method:
<module name="Checker">
<module name="TreeWalker">
<module name="ParameterNumber">
<property name="max" value="10"/>
<property name="tokens" value="METHOD_DEF"/>
</module>
</module>
</module>
Example:
class Example2 extends ExternalService2 {
@JsonCreator
// ok below, constructor is not in tokens to check
Example2(int a, int b, int c, int d,
int e, int f, int g, int h) {}
// ok below, constructor is not in tokens to check
Example2(String a, String b, String c, String d,
String e, String f, String g, String h) {}
@Override
// ok below, less than 10 parameters (found 8)
public void processData(String a, String b, String c, String d,
String e, String f, String g, String h) {}
}
class ExternalService2 {
// ok below, less than 10 parameters (found 8)
public void processData(String a, String b, String c, String d,
String e, String f, String g, String h) {}
}
To configure the check to ignore number of parameters for methods with
@Override or @java.lang.Override annotation.
Rationale: developer may need to override method with many parameters from 3-rd party library. In this case developer has no control over number of parameters.
<module name="Checker">
<module name="TreeWalker">
<module name="ParameterNumber">
<property name="ignoreOverriddenMethods" value="true"/>
</module>
</module>
</module>
Example:
class Example3 extends ExternalService3 {
@JsonCreator
// violation below, 'More than 7 parameters (found 8)'
Example3(int a, int b, int c, int d,
int e, int f, int g, int h) {}
// violation below, 'More than 7 parameters (found 8)'
Example3(String a, String b, String c, String d,
String e, String f, String g, String h) {}
@Override
// ok below, overridden method is ignored
public void processData(String a, String b, String c, String d,
String e, String f, String g, String h) {}
}
class ExternalService3 {
// violation below, 'More than 7 parameters (found 8)'
public void processData(String a, String b, String c, String d,
String e, String f, String g, String h) {}
}
To configure the check to ignore methods and constructors annotated with
JsonCreator annotation:
<module name="Checker">
<module name="TreeWalker">
<module name="ParameterNumber">
<property name="ignoreAnnotatedBy" value="JsonCreator"/>
</module>
</module>
</module>
Example:
class Example4 extends ExternalService4 {
@JsonCreator
// ok below, constructor annotated with JsonCreator annotation is ignored
Example4(int a, int b, int c, int d,
int e, int f, int g, int h) {}
// violation below, 'More than 7 parameters (found 8)'
Example4(String a, String b, String c, String d,
String e, String f, String g, String h) {}
@Override
// violation below, 'More than 7 parameters (found 8)'
public void processData(String a, String b, String c, String d,
String e, String f, String g, String h) {}
}
class ExternalService4 {
// violation below, 'More than 7 parameters (found 8)'
public void processData(String a, String b, String c, String d,
String e, String f, String g, String h) {}
}
Note: Annotation names specified in the ignoreAnnotatedBy property
must be an exact match for the annotation name on the method or constructor.
All messages can be customized if the default message doesn't suit you. Please see the documentation to learn how to.
com.puppycrawl.tools.checkstyle.checks.sizes