Just Java™ 2

Widening and Narrowing Conversions

This section provides more details on when a cast is needed, and also introduces the terminology of type conversions. This is explained in terms of an assignment between one variable and another, and exactly the same rules apply in the transfer of values from actual parameters to formal parameters.

When you assign an expression to a variable, a conversion must be done. Conversions among the primitive types are either identity, widening, or narrowing conversions.

• Identity conversions are an assignment between two identical types, like an int to int assignment. The conversion is trivial: just copy the bits unchanged.

• Widening conversions occur when you assign from a less capacious type (such as a short) ...