Java hashmap syntax changes after 1.5.

First of all, we don't need to talk about the basics of hashmap. Here we will talk about its changes after 1.5. When we were doing Java, we would say hashmap was written like this: map xxx = new hashmap (); a yellow alarm may appear. This is the syntax of later versions of Java, called generic writing. After this definition, when a hashmap is followed by a key-value pair, the string type must be used as the key, and the float type must be used as the value.

The advantage is to clearly tell JVM how to allocate memory space to it, which can improve JVM efficiency and optimize memory storage.

 

 

 

In fact, no matter how it is written, it is not easy to keep the yellow warning. The level is limited!