Java SE 10 (March 2018) introduced type inference for local variables. Java Language Architect Brian Goetz explains the feature.

When you use a var to declare a variable, the JVM assigns a type to the variable based on what it sees on the right-hand side of the assignment operation. That’s why the var reserved word is said to ...

Type erasure in Java generics programming can cause a variety of problems in your code. Fortunately, there are ways to work around them.