Since Checkstyle 5.0


Checks that the whitespace around the Generic tokens (angle brackets) "<" and ">" are correct to the typical convention. The convention is not configurable.

Left angle bracket ("<"):

  • should be preceded with whitespace only in generic methods definitions.
  • should not be preceded with whitespace when it is preceded method name or constructor.
  • should not be preceded with whitespace when following type name.
  • should not be followed with whitespace in all cases.

Right angle bracket (">"):

  • should not be preceded with whitespace in all cases.
  • should be followed with whitespace in almost all cases, except diamond operators and when preceding a method name, constructor, or record header.


To configure the check:

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

Examples with correct spacing:

// Generic methods definitions
public void <K, V extends Number> boolean foo(K, V) {}
// Generic type definition
class name<T1, T2, ..., Tn> {}
// Generic type reference
OrderedPair<String, Box<Integer>> p;
// Generic preceded method name
boolean same = Util.<Integer, String>compare(p1, p2);
// Diamond operator
Pair<Integer, String> p1 = new Pair<>(1, "apple");
// Method reference
List<T> list = ImmutableList.Builder<T>::new;
// Method reference
sort(list, Comparable::<String>compareTo);
// Constructor call
MyClass obj = new <String>MyClass();
// Record header
record License<T>() {}

Examples with incorrect spacing:

List< String> l; // violation, "<" followed by whitespace
Box b = Box. <String>of("foo"); // violation, "<" preceded with whitespace
public<T> void foo() {} // violation, "<" not preceded with whitespace

List a = new ArrayList<> (); // violation, ">" followed by whitespace
Map<Integer, String>m; // violation, ">" not followed by whitespace
Pair<Integer, Integer > p; // violation, ">" preceded with whitespace

record License<T> () {} // violation, ">" followed by whitespace

Example of Usage

Violation Messages

All messages can be customized if the default message doesn't suit you. Please see the documentation to learn how to.


Parent Module