java - 对于java泛型来说<>意味着什么？

Question

我有一些代码:

class MyClass<RCM> 
  private List<RCM> allPreExistingConfigsForCodes() {
    if(this.allCodesForThisType.size() == 0)
       return new ArrayList<RCM>(0);

IntelliJ 告诉我应该替换 new ArrayList<RCM>与 new ArrayList<>这意味着什么？

Answer 1

来自Java Tutorials generics lesson :

In Java SE 7 and later, you can replace the type arguments required to invoke the constructor of a generic class with an empty set of type arguments (<>) as long as the compiler can determine, or infer, the type arguments from the context. This pair of angle brackets, <>, is informally called the diamond. For example, you can create an instance of Box<Integer> with the following statement:

Box<Integer> integerBox = new Box<>();