Compulsory non-null initialization

A local variable defined with var must be initialized with its declaration, or the code won't compile. The compiler can't infer the type of an uninitialized variable or a variable that is assigned a null value. The following code won't compile:

var minAge;                   // uninitialized variable 
var age = null;               // variable assigned a null value  

The following image illustrates what would happen if the uninitialized variable age went to seek entrance to the Mr. Java compiler place. The compiler won't let age in: