jwalgemoed

// Classic declaration, we are repeating ourselves
Integer ten = new Integer(10);

// New declaration, using 'var' 
var ten = new Integer(10);

jwalgemoed

class SomeClass {
    // Kotlin allows this, as you can specify the intended type here
    var property: String
}

jwalgemoed

// Can't use the local variable type inference with fields
public class SomeClass {
    // Not allowed, var is only available for local variables
    var property = "";
}

// Can't leave values unitialzed
var uninitialized; // No way to infer the type

// Can't just assign null to var to reassign later (but workaround available)

jwalgemoed

// Classic declaration
ArrayList<Integer> list = new ArrayList<Integer>();

// But honestly, since Java 7 Java we can use the diamond operator <> (or omit it entirely)
ArrayList<Integer> list = new ArrayList();

// Var declaration
var list = new ArrayList<Integer>();