Description

Properties

Examples

To configure the check:

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

Examples of using Unicode:

public class Example1 {
  // OK, perfectly clear even without a comment.
  String unitAbbrev = "μs";
  // violation below, the reader has no idea what this is. 'should be avoided.'
  String unitAbbrev1 = "\u03bcs";
  // violation below
  String unitAbbrev2 = "\u03bc\u03bc\u03bc";
  // violation below
  String unitAbbrev3 = "\u03bcs"; // it is  μs
  // violation below
  String unitAbbrev4 = "\u03bc\u03bcs";
  public static int content() {
    char content = 'r';
    // violation below
    return '\ufeff' + content;
  }
}
        

An example of how to configure the check to allow using escapes for non-printable, control characters:

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidEscapedUnicodeCharacters">
      <property name="allowEscapesForControlCharacters" value="true"/>
    </module>
  </module>
</module>
        

Example of using escapes for non-printable, control characters:

public class Example2 {
  // OK, a normal String below
  String unitAbbrev = "μs";
  // violation below, μs is a printable character. 'should be avoided.'
  String unitAbbrev1 = "\u03bcs";
  // violation below
  String unitAbbrev2 = "\u03bc\u03bc\u03bc";
  // violation below
  String unitAbbrev3 = "\u03bcs";
  // violation below
  String unitAbbrev4 = "\u03bc\u03bcs";
  public static int content() {
    char content = 'r';
    // OK, non-printable control character.
    return '\ufeff' + content;
  }
}
        

An example of how to configure the check to allow using escapes if trail comment is present:

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidEscapedUnicodeCharacters">
      <property name="allowByTailComment" value="true"/>
    </module>
  </module>
</module>
        

Example of using escapes if trail comment is present:

public class Example3 {
  // OK, a normal String below
  String unitAbbrev = "μs";
  // violation below
  String unitAbbrev1 = "\u03bcs";
  // violation below
  String unitAbbrev2 = "\u03bc\u03bc\u03bc";
  // violation below
  String unitAbbrev3 = "\u03bcs";
  // ok, because there is trailing comment and allowByTailComment=true
  String unitAbbrev4 = "\u03bc\u03bcs"; // it is  μs
  public static int content() {
    char content = 'r';
    // violation below
    return '\ufeff' + content;
  }
}
        

An example of how to configure the check to allow if all characters in literal are escaped.

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidEscapedUnicodeCharacters">
      <property name="allowIfAllCharactersEscaped" value="true"/>
    </module>
  </module>
</module>
        

Example of using escapes if all characters in literal are escaped:

public class Example4 {
  // OK, a normal String below
  String unitAbbrev = "μs";
  // violation below, not all characters are escaped ('s'). 'should be avoided.'
  String unitAbbrev1 = "\u03bcs";
  // ok, because below are escape characters and allowIfAllCharacters = true.
  String unitAbbrev2 = "\u03bc\u03bc\u03bc";
  // violation below
  String unitAbbrev3 = "\u03bcs"; // it is  μs
  // violation below, not all characters are escaped ('s'). 'should be avoided.'
  String unitAbbrev4 = "\u03bc\u03bcs";
  public static int content() {
    char content = 'r';
    // OK, all control characters are escaped below
    return '\ufeff' + content;
  }
}
        

An example of how to configure the check to allow using escapes for non-printable whitespace characters:

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidEscapedUnicodeCharacters">
      <property name="allowNonPrintableEscapes" value="true"/>
    </module>
  </module>
</module>
        

Example of using escapes for non-printable whitespace characters:

public class Example5 {
  // OK, a normal String below.
  String unitAbbrev = "μs";
  // violation below, printable escape character. 'should be avoided.'
  String unitAbbrev1 = "\u03bcs";
  // violation below, printable escape character. 'should be avoided.'
  String unitAbbrev2 = "\u03bc\u03bc\u03bc";
  // violation below
  String unitAbbrev3 = "\u03bcs"; // it is μs
  // violation below
  String unitAbbrev4 = "\u03bc\u03bcs";
  public static int content() {
    char content = 'r';
    // OK, non-printable escape character below
    return '\ufeff' + content;
  }
}
        

Example of Usage

• Google Style
• Checkstyle Style

Violation Messages

• forbid.escaped.unicode.char

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

Parent Module

TreeWalker