java - Java中HashMap定义的有效性？

Question

这个问题已经有答案了:

What is the point of the diamond operator (<>) in Java? (7 个回答)

已关闭 5 年前。

class Node {
    long data;
    Node node;
    int rank;
}

1. private Map<Long, Node> map = new HashMap<>();

2. private Map<Long, Node> map = new HashMap<Long,Node>();

我正在实现 Node 类的 hashmap

我的问题是上面提到的两个Hashmaps的有效性。(两者是否都是coreect？)。如果它们有效，那么两个初始化有什么区别？

Answer 1

根据文档:https://docs.oracle.com/javase/tutorial/java/generics/types.html

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.

从 Java 7 开始，两者都是正确的。