Description

Notes

It is possible to configure the check to ignore all property setter methods.

A method is recognized as a setter if it is in the following form

${returnType} set${Name}(${anyType} ${name}) { ... }
        

where ${anyType} is any primitive type, class or interface name; ${name} is name of the variable that is being set and ${Name} its capitalized form that appears in the method name. By default, it is expected that setter returns void, i.e. ${returnType} is 'void'. For example

void setTime(long time) { ... }
        

Any other return types will not let method match a setter pattern. However, by setting setterCanReturnItsClass property to true definition of a setter is expanded, so that setter return type can also be a class in which setter is declared. For example

class PageBuilder {
  PageBuilder setName(String name) { ... }
}
        

Such methods are known as chain-setters and a common when Builder-pattern is used. Property setterCanReturnItsClass has effect only if ignoreSetter is set to true.

Properties

Examples

To configure the check:

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

Example:

class Example1 {

  private String field;
  private String testField;

  Example1(String testField) { // violation, 'field' hides a field
  }
  void method(String param) {
    String field = param; // violation, ''field' hides a field'
  }
  void setTestField(String testField) { // violation, ''testField' hides a field'
    this.field = field;
  }
  Example1 setField(String field) { // violation, ''field' hides a field'
    this.field = field;
    return null;
  }
  abstract class Inner {
    abstract int method(String field); // violation, ''field' hides a field'
  }
}
        

To configure the check so that it checks local variables but not parameters:

<module name="Checker">
  <module name="TreeWalker">
    <module name="HiddenField">
      <property name="tokens" value="VARIABLE_DEF"/>
    </module>
  </module>
</module>
        

Example:

class Example2 {

  private String field;
  private String testField;

  Example2(String testField) { // OK, because PARAMETER_DEF not configured
  }
  void method(String param) {
    String field = param; // violation, ''field' hides a field'
  }
  void setTestField(String testField) { // OK, because PARAMETER_DEF not configured
    this.field = field;
  }
  Example2 setField(String field) { // OK, because PARAMETER_DEF not configured
    this.field = field;
    return null;
  }
  abstract class Inner {
    abstract int method(String field); // OK, because PARAMETER_DEF not configured
  }
}
        

To configure the check so that it ignores the variables and parameters named "test":

<module name="Checker">
  <module name="TreeWalker">
    <module name="HiddenField">
      <property name="ignoreFormat" value="^testField"/>
    </module>
  </module>
</module>
        

Example:

class Example3 {

  private String field;
  private String testField;

  Example3(String testField) { // OK, because it match ignoreFormat
  }
  void method(String param) {
    String field = param; // violation, ''field' hides a field'
  }
  void setTestField(String testField) { // OK, because it match ignoreFormat
    this.field = field;
  }
  Example3 setField(String field) { // violation, ''field' hides a field'
    this.field = field;
    return null;
  }
  abstract class Inner {
    abstract int method(String field); // violation, ''field' hides a field'
  }
}
        

To configure the check so that it ignores constructor parameters:

<module name="Checker">
  <module name="TreeWalker">
    <module name="HiddenField">
      <property name="ignoreConstructorParameter" value="true"/>
    </module>
  </module>
</module>
        

Example:

class Example4 {

  private String field;
  private String testField;

  Example4(String testField) { // OK, because ignoreConstructorParameter is true
  }
  void method(String param) {
    String field = param; // violation, ''field' hides a field' field
  }
  void setTestField(String testField) { // violation, ''testField' hides a field'
    this.field = field;
  }
  Example4 setField(String field) { // violation, ''field' hides a field'
    this.field = field;
    return null;
  }
  abstract class Inner {
    abstract int method(String field); // violation, ''field' hides a field'
  }
}
        

To configure the check so that it ignores the parameter of setter methods:

<module name="Checker">
  <module name="TreeWalker">
    <module name="HiddenField">
      <property name="ignoreSetter" value="true"/>
    </module>
  </module>
</module>
        

Example:

class Example5 {

  private String field;
  private String testField;

  Example5(String testField) { // violation, ''testField' hides a field'
  }
  void method(String param) {
    String field = param; // violation, ''field' hides a field'
  }
  void setTestField(String testField) { // OK, because ignoreSetter is true
    this.field = field;
  }
  Example5 setField(String field) { // violation, ''field' hides a field'
    this.field = field;
    return null;
  }
  abstract class Inner {
    abstract int method(String field); // violation, ''field' hides a field'
  }
}
        

To configure the check so that it ignores the parameter of setter methods recognizing setter as returning either void or a class in which it is declared:

<module name="Checker">
  <module name="TreeWalker">
    <module name="HiddenField">
      <property name="ignoreSetter" value="true"/>
      <property name="setterCanReturnItsClass" value="true"/>
    </module>
  </module>
</module>
        

Example:

class Example6 {

  private String field;
  private String testField;

  Example6(String testField) { // violation, ''testField' hides a field'
  }
  void method(String param) {
    String field = param; // violation, ''field' hides a field'
  }
  void setTestField(String testField) { // OK, because ignoreSetter is true
    this.field = field;
  }
  Example6 setField(String field) { // OK, because setterCanReturnItsClass is true
    this.field = field;
    return null;
  }
  abstract class Inner {
    abstract int method(String field); // violation, ''field' hides a field'
  }
}
        

To configure the check so that it ignores parameters of abstract methods:

<module name="Checker">
  <module name="TreeWalker">
    <module name="HiddenField">
      <property name="ignoreAbstractMethods" value="true"/>
    </module>
  </module>
</module>
        

Example:

class Example7 {

  private String field;
  private String testField;

  Example7(int field) { // violation, ''field' hides a field'
    this.field = Integer.toString(field);
  }
  void method(String param) {
    String field = param; // violation, ''field' hides a field'
  }
  void setTestField(String testField) { // violation, 'testField' hides a field'
    this.field = field;
  }
  Example7 setField(String field) { // violation, ''field' hides a field'
    this.field = field;
    return null;
  }
  abstract class Inner {
    abstract int method(String field); // OK, because ignoreAbstractMethods is true
  }
}
        

Example of Usage

• Sun Style
• Checkstyle Style

Violation Messages

• hidden.field

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.coding

Parent Module

TreeWalker