Learning Java

Math Utilities

Java supports integer and floating-point arithmetic directly. Higher-level math operations are supported through the java.lang.Math class. Java provides wrapper classes for all primitive data types, so you can treat them as objects if necessary. Java also provides the java.util.Random class for generating random numbers.

Java handles errors in integer arithmetic by throwing an ArithmeticException:

int zero = 0;  
  
try {  
    int i = 72 / zero;  
}   
catch ( ArithmeticException e ) {
    // division by zero
}

To generate the error in this example, we created the intermediate variable zero. The compiler is somewhat crafty and would have caught us if we had blatantly tried to perform a division by a literal zero.

Floating-point arithmetic expressions, on the other hand, don’t throw exceptions. Instead, they take on the special out-of-range values shown in Table 9.3.

Table 9-3. Special Floating-Point Values

Value	Mathematical Representation
POSITIVE_INFINITY	1.0/0.0
NEGATIVE_INFINITY	-1.0/0.0
NaN	0.0/0.0

The following example generates an infinite result:

double zero = 0.0;  
double d = 1.0/zero;  
  
if ( d == Double.POSITIVE_INFINITY )  
    System.out.println( "Division by zero" );

The special value NaN indicates the result is “not a number.” The value NaN has the special distinction of not being equal to itself (NaN != NaN evaluates to true). Use Float.isNaN( ) or Double.isNaN( ) to test for NaN.

The java.lang.Math Class

The java.lang.Math class provides Java’s math library. All ...