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

Class ParameterAssignmentCheck

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

    Disallows assignment of parameters.

    Rationale: Parameter assignment is often considered poor programming practice. Forcing developers to declare parameters as final is often onerous. Having a check ensure that parameters are never assigned would give the best of both worlds.

    To configure the check: 

     <module name="ParameterAssignment"/>

    Example: 

     class MyClass {
   int methodOne(int parameter) {
     if (parameter <= 0 ) {
       throw new IllegalArgumentException("A positive value is expected");
     }
     parameter -= 2;  // violation
     return parameter;
   }

   int methodTwo(int parameter) {
     if (parameter <= 0 ) {
       throw new IllegalArgumentException("A positive value is expected");
     }
     int local = parameter;
     local -= 2;  // OK
     return local;
   }

   IntPredicate obj = a -> ++a == 12; // violation
   IntBinaryOperator obj2 = (int a, int b) -> {
       a++;     // violation
       b += 12; // violation
       return a + b;
   };
   IntPredicate obj3 = a -> {
       int b = a; // ok
       return ++b == 12;
   };
 }

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Violation Message Keys:

    • parameter.assignment
    Since:
    3.2

    • 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

      • parameterNamesStack

        private final java.util.Deque<java.util.Set<java.lang.String>> parameterNamesStack
        Stack of methods' parameters.

      • parameterNames

        private java.util.Set<java.lang.String> parameterNames
        Current set of parameters.