Package com.puppycrawl.tools.checkstyle.checks.coding

Class InnerAssignmentCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable
    public class InnerAssignmentCheck
extends AbstractCheck

    Checks for assignments in subexpressions, such as in String s = Integer.toString(i = 2);.

    Rationale: With the exception of for iterators and assignment in while idiom, all assignments should occur in their own top-level statement to increase readability. With inner assignments like the one given above, it is difficult to see all places where a variable is set.

    Note: Check allows usage of the popular assignment in while idiom: 

     String line;
 while ((line = bufferedReader.readLine()) != null) {
   // process the line
 }

    Assignment inside a condition is not a problem here, as the assignment is surrounded by an extra pair of parentheses. The comparison is != null and there is no chance that intention was to write line == reader.readLine().

    To configure the check: 

     <module name="InnerAssignment"/>

    Example:

     class MyClass {

   void foo() {
     int a, b;
     a = b = 5; // violation, assignment to each variable should be in a separate statement
     a = b += 5; // violation

     a = 5; // OK
     b = 5; // OK
     a = 5; b = 5; // OK

     double myDouble;
     double[] doubleArray = new double[] {myDouble = 4.5, 15.5}; // violation

     String nameOne;
     List<String> myList = new ArrayList<String>();
     myList.add(nameOne = "tom"); // violation
     for (int k = 0; k < 10; k = k + 2) { // OK
       // some code
     }

     boolean someVal;
     if (someVal = true) { // violation
       // some code
     }

     while (someVal = false) {} // violation

     InputStream is = new FileInputStream("textFile.txt");
     while ((b = is.read()) != -1) { // OK, this is a common idiom
       // some code
     }

   }

   boolean testMethod() {
     boolean val;
     return val = true; // violation
   }
 }

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Violation Message Keys:

    • assignment.inner.avoid
    Since:
    3.0

    • Field Detail

      • MSG_KEY

        public static final java.lang.String MSG_KEY
        A key is pointing to the warning message text in "messages.properties" file.
        See Also:
        Constant Field Values

    • Constructor Detail

      • InnerAssignmentCheck

        public InnerAssignmentCheck()

    • Method Detail

      • getDefaultTokens

        public int[] getDefaultTokens()
        Description copied from class: AbstractCheck
        Returns the default token a check is interested in. Only used if the configuration for a check does not define the tokens.
        Specified by:
        getDefaultTokens in class AbstractCheck
        Returns:
        the default tokens
        See Also:
        TokenTypes

      • getAcceptableTokens

        public int[] getAcceptableTokens()
        Description copied from class: AbstractCheck
        The configurable token set. Used to protect Checks against malicious users who specify an unacceptable token set in the configuration file. The default implementation returns the check's default tokens.
        Specified by:
        getAcceptableTokens in class AbstractCheck
        Returns:
        the token set this check is designed for.
        See Also:
        TokenTypes

      • getRequiredTokens

        public int[] getRequiredTokens()
        Description copied from class: AbstractCheck
        The tokens that this check must be registered for.
        Specified by:
        getRequiredTokens in class AbstractCheck
        Returns:
        the token set this must be registered for.
        See Also:
        TokenTypes