ArrayBracketNoWhitespace

Since Checkstyle 13.1.0

Description

Checks that the whitespace around square-bracket tokens [ and ] follows the Google Java Style Guide requirements for array declarations, array creation, and array indexing.

Left square bracket ("["):

must not be preceded with whitespace when preceded by a TYPE or IDENT in array declarations or array access
must not be followed with whitespace

Right square bracket ("]"):

must not be preceded with whitespace
must be followed with whitespace in all cases, except when followed by:
- another bracket: [][]
- a dot for member access: arr[i].length
- a comma or semicolon: arr[i], or arr[i];
- postfix operators: arr[i]++ or arr[i]--
- a right parenthesis or another closing construct: (arr[i])

Examples

To configure the check:


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

Example:


class Example1 {
  int[] numbersWarn = new int[10 ]; // violation, ']' is preceded with whitespace
  int[] numbersGood = new int[10];

  String [] dataWarn = {"a", "b"}; // violation, '[' is preceded with whitespace
  String[] dataGood = {"a", "b"};

  byte bufferWarn[ ];
  // 2 violations above
  // '[' is followed by whitespace
  // ']' is preceded with whitespace
  byte bufferGood[];

  int[] matrixWarn[] ; // violation, ']' is followed by whitespace
  int[] matrixGood[];

  void processArray(int[] arr) {
    int value = arr [0]; // violation, '[' is preceded with whitespace
    int valueGood = arr[0];
  }

  void calculateWarn(int values[ ]) {
    // 2 violations above
    // '[' is followed by whitespace
    // ']' is preceded with whitespace
  }
  void calculateGood(int values[]) {
  }
  void processData(int[] values, String[] labels) {
    for (int i = 0; i < values.length; i++) {
      values[i] = values[i] * 2;
    }
  }

  void initializeData() {
    String[] namesWarn = new String[ 5 ];
    // 2 violations above
    // '[' is followed by whitespace
    // ']' is preceded with whitespace
    String[] namesGood = new String[5];

    int[][] gridWarn = new int[3 ][4]; // violation, ']' is preceded with whitespace
    int[][] gridGood = new int[3][4];
    int[][] correctGrid = new int[5][5];
    correctGrid[0][0] = 1;
  }
}

Example of Usage

Checkstyle Style

Violation Messages

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.whitespace

Parent Module

TreeWalker