Class UnnecessaryParenthesesCheck

Checks if unnecessary parentheses are used in a statement or expression. The check will flag the following with warnings:

     return (x);          // parens around identifier
     return (x + 1);      // parens around return value
     int x = (y / 2 + 1); // parens around assignment rhs
     for (int i = (0); i < 10; i++) {  // parens around literal
     t -= (z + 1);        // parens around assignment rhs

The check is not "type aware", that is to say, it can't tell if parentheses are unnecessary based on the types in an expression. It also doesn't know about operator precedence and associativity; therefore it won't catch something like

     int x = (a + b) + c;

In the above case, given that a, b, and c are all int variables, the parentheses around a + b are not needed.

• Property tokens - tokens to check Type is java.lang.String[]. Validation type is tokenSet. Default value is: EXPR, IDENT, NUM_DOUBLE, NUM_FLOAT, NUM_INT, NUM_LONG, STRING_LITERAL, LITERAL_NULL, LITERAL_FALSE, LITERAL_TRUE, ASSIGN, BAND_ASSIGN, BOR_ASSIGN, BSR_ASSIGN, BXOR_ASSIGN, DIV_ASSIGN, MINUS_ASSIGN, MOD_ASSIGN, PLUS_ASSIGN, SL_ASSIGN, SR_ASSIGN, STAR_ASSIGN, LAMBDA, TEXT_BLOCK_LITERAL_BEGIN.

To configure the check:

 <module name="UnnecessaryParentheses"/>
 

Which results in the following violations:

 public int square(int a, int b){
   int square = (a * b); //violation
   return (square); //violation
 }
 int sumOfSquares = 0;
 for(int i=(0); i<10; i++){ //violation
   int x = (i + 1); //violation
   sumOfSquares += (square(x * x)); //violation
 }
 double num = (10.0); //violation
 List<String> list = Arrays.asList("a1", "b1", "c1");
 myList.stream()
   .filter((s) -> s.startsWith("c")) //violation
   .forEach(System.out::println);
 

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

• unnecessary.paren.assign
• unnecessary.paren.expr
• unnecessary.paren.ident
• unnecessary.paren.lambda
• unnecessary.paren.literal
• unnecessary.paren.return
• unnecessary.paren.string