Data and Expressions - Java Software Solutions: Foundations of Program Design - page 83

SR 2.27 What value is contained in the integer variable result after the
following sequence of statements is executed?
result = 27;
result = result + 3;
result = result / 7;
result = result * 2;
SR 2.28 What value is contained in the integer variable result after the
following sequence of statements is executed?
int base;
int result;
base = 5;
result = base + 3;
base = 7;
SR 2.29 What is an assignment operator?
SR 2.30 If an integer variable weight currently holds the value 100, what is its
value after the following statement is executed? Explain.
weight -= 17;
2.5 Data Conversion
Because Java is a strongly typed language, each data value is associated with a
particular type. It is sometimes helpful or necessary to convert a data value of
one type to another type, but we must be careful that we don't lose important
information in the process. For example, suppose a short variable that holds the
number 1000 is converted to a byte value. Because a byte does not have enough
bits to represent the value 1000, some bits would be lost in the conversion, and
the number represented in the byte would not keep its original value.
A conversion between one primitive type and another falls into one of two
categories: widening conversions and narrowing conversions. Widening conver-
sions are the safest because they usually do not lose information. They are called
widening conversions because they go from one data type to another type that
uses an equal or greater amount of space to store the value. Figure 2.5 lists the
Java widening conversions.
For example, it is safe to convert from a byte to a short because a byte is stored
in 8 bits and a short is stored in 16 bits. There is no loss of information. All widening
conversions that go from an integer type to another integer type, or from a floating
point type to another floating point type, preserve the numeric value exactly.